Next Article in Journal
The Combined Use of Soil Conditioner and Foliar Sulfur Spray Successfully Prevents Dark Pericarp Disease Induced by Manganese Toxicity in Litchi
Previous Article in Journal
Discrete Element Method–Multibody Dynamics Coupling Simulation and Experiment of Rotary Tillage and Ridging Process for Chili Pepper Cultivation
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Agronomy
Volume 14
Issue 3
10.3390/agronomy14030447
agronomy-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Enhancing Faba Bean Yields in Alpine Agricultural Regions: The Impact of Plastic Film Mulching and Phosphorus Fertilization on Soil Dynamics

by
Yanjie Gu
1,
Qiuyun Xu
1,
Weidi Zhou
1,
Chenglong Han
2,* and
Kadambot H. M. Siddique
3
1
College of Agriculture and Animal Husbandry, Qinghai University, Xining 810016, China
2
State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining 810016, China
3
The UWA Institute of Agriculture, The University of Western Australia, Perth, WA 6009, Australia
*
Author to whom correspondence should be addressed.
Agronomy 2024, 14(3), 447; https://doi.org/10.3390/agronomy14030447
Submission received: 31 January 2024 / Revised: 19 February 2024 / Accepted: 21 February 2024 / Published: 24 February 2024
(This article belongs to the Section Soil and Plant Nutrition)
Browse Figures
Versions Notes

Abstract

:
Plastic film mulching is widely used in water and temperature-limited regions to enhance crop yields. Phosphorus (P) fertilization can address deficiencies in soil P availability. In this four-year field experiment conducted in an alpine agricultural area, we explored the effects of nitrogen (N) and P supply imbalance on faba bean cultivation, particularly examining intensified N competition between soil microbes and plants. The randomized block design comprised three film mulching treatments—no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)—and three P levels—P0 (0 kg P ha−1), P1 (9.10 kg P ha−1), and P2 (18.2 kg P ha−1). The results indicated that NMF enhanced soil available N and microbial biomass N (MBN) during early growth stages, consequently improving faba bean yield, nodule weight, total N, and microbial biomass carbon (MBC) compared to DRM and TRM. DRM and TRM exhibited higher soil available N and MBN during later growth stages and higher soil temperature and water content, soil water storage (SWS), soil organic C (SOC), and soil C/N ratio than NMF. In NMF and DRM, P fertilization increased grain yield, nodule weight, SOC, total N, soil C/N ratio, soil available N, and MBC but decreased MBN during early growth stages, and decreased soil water content and SWS. TRM exhibited the opposite trend. P fertilization increased soil total P and available P. Overall, NMF combined with P fertilization (~18.2 kg P ha−1) significantly improved faba bean yield. However, it may also accelerate SOC decomposition, highlighting the need to consider N fertilizer application in this alpine agricultural region.

1. Introduction

In alpine agriculture, crucial environmental factors like low mean annual temperatures and significant temperature fluctuations between day and night determine crop productivity. The eastern agricultural region of Qinghai Province, located between the Loess Plateau and Qinghai-Tibet Plateau, experiences a semi-arid climate predominantly characterized by dryland agriculture [1]. While this region benefits from abundant sunlight, the low temperatures and irregular precipitation challenge sustainable agricultural development [2]. Faba bean (Vicia faba L.)—rich in protein, carbohydrates, and minerals—is widely used as a food crop and livestock feed [3]. Due to its cultivation area, faba bean has evolved as a significant cool-season crop, well-adapted to low-temperature environments [4]. Moreover, faba bean cultivation is an effective strategy for enhancing soil fertility and altering soil structure through systematic crop rotation, contributing to sustainable agricultural systems [5]. However, water deficit, extremely low temperatures, and limited soil nutrient availability constrain faba bean growth and productivity [4]. Hence, exploring effective cultivation techniques that enhance soil temperature, moisture, and nutrient conditions is crucial to promote faba bean productivity.
Plastic film mulching can improve the soil hydrothermal regime by hindering water–gas exchange between the soil and atmosphere, reducing heat loss, increasing solar radiation absorption, and optimizing resource (water, nutrient, and radiation) utilization, making it a widely adopted practice in dryland planting, especially in arid and semi-arid areas [2,6,7,8,9,10]. This technique has been instrumental in areas where irrigation is unavailable and spring temperatures are low [11,12], significantly reducing harvest time and nearly doubling grain yield [13]. Different mulching and planting practices can influence soil water retention, temperature stability, and resource use, affecting crop yield in diverse climatic zones [1,14]. The ridge–furrow with plastic film mulching technique, using ridges for rainwater harvesting and furrows for planting, efficiently increases soil temperature and facilitates rainfall infiltration, enhancing soil water availability and grain yield in arid and semi-arid regions [6,15]. Double ridge–furrow systems with full plastic film mulching greatly increase maize grain yield and resource use efficiency [1,11]. In recent years, tripe ridge–furrow systems mulched with one plastic film have significantly improved faba bean productivity in the eastern agricultural area of Qinghai Province.
While plastic film mulching improves the soil hydrothermal environment, increasing soil nutrient (nitrogen (N) and phosphorus (P)) availability and extending the reproductive growth period [1,16,17], long-term film mulching has been associated with challenges like accelerated organic matter decomposition, leading to increased competition for available nutrients between plants and soil microbes [18]. Nutrient limitation, particularly N and P, is widespread in terrestrial ecosystems [19,20]. Momen et al. [20] reported that N limitation reduced maize dry matter yield by 11% and 20%, compared with moderate and high N supply. Faba bean fixes atmospheric N through its symbiotic relationship with specific rhizobia [5], but soil N and P availability and other soil conditions can affect nodule formation and inoculant bacteria survival [21,22]. P is a key component of phospholipids, nucleic acids, adenosine triphosphate (ATP), and sugar phosphates, serving as a fundamental building block for all life forms [22,23]. P limitation during early growth stages can delay leaf emergence, reduce leaf development, and decrease cumulative absorbed radiation, resulting in yield reductions [20]. Applying P fertilizer is a common practice to overcome low soil P availability and enhance crop production [17,22,24]. The intricate relationship between N and P cycling underscores the impact of P availability on soil N dynamics [22,25], influencing N fixation rates and availability in many ecosystems [19]. However, an imbalance in soil N and P supplies may exacerbate soil microbial N limitation, increasing plant N uptake [23,26]. For example, P application can increase gaseous N losses by stimulating denitrification, increasing soil microbial N limitation [25,27], and potentially increasing microbial soil organic carbon (SOC) decomposition for N acquisition [27,28]. One study showed that high P levels decreased soil available N content and intensified the competition for N between soil microbes and plants in an alfalfa artificial grassland under plastic film mulching and P fertilization [29].
This study addresses gaps in understanding how soil nutrient availability, particularly N, affects faba bean and soil microbes under plastic film mulching combined with P fertilizer in semi-arid, alpine agricultural fields in Qinghai Province. The main objectives were to (1) investigate the effects of different film mulching regimes and P fertilizer levels on faba bean yield, soil water and temperature conditions, and soil biochemical properties and (2) identify potential limitations imposed by soil N availability on faba bean and soil microbes under these conditions.

2. Materials and Methods

2.1. Site Description

The field experiment was conducted in Xiliangqi Village (36°33′ N, 101°36′ E, 2493 m above sea level), Huangzhong County, Qinghai Province, China. This region experiences a mean annual precipitation of ~542 mm, with 64% occurring between April and August (Figure 1). Monthly mean air temperatures range from −8.7 °C in January to 16.8 °C in July, averaging 5.0 °C annually. The soil type, classified as chestnut soil, has 1.44 g cm−3 soil bulk density, pH 8.01, 10.2 g kg−1 organic C, 1.02 g kg−1 total N, 0.769 g kg−1 total P, 1.70 mg kg−1 NH4+-N, 4.48 mg kg−1 NO3−-N, and 4.51 mg kg−1 available P.

2.2. Experimental Design and Field Management

From 2020 to 2023, we conducted a field experiment incorporating a randomized block design featuring faba bean (Vicia faba L.) cultivar ‘Qinghai 13’. The study included three film mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P fertilizer levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)]. The second P level (P1) corresponded to the typical P fertilizer rate used for faba bean cultivation in the local area, while the doubled P level (P2) was introduced to identify the optimum P fertilizer level for faba bean production. The P fertilizer used was CaP2H4O8 (P2O5 ≥ 12%), broadcast in early April each year and plowed into the top 20 cm of each plot using a rotary cultivator. No other fertilizers were applied. Colorless, transparent plastic film (0.008 mm thick and 1.2 m wide) was fully mulched on the ridge and furrow surfaces for the film mulching treatments. About one week later, faba bean seeds were planted 15 cm apart in each row using a dibbler. Twenty-seven plots were established, each measuring 16.7 m in length and 4.2 m in width, with three biological replications for each treatment. Faba bean harvesting occurred in late August each year, followed by faba bean residue removal, leaving the plastic film in situ on the field surface for the entire year. Weeds were removed manually, and no irrigation was applied, relying solely on rainfall for all water inputs.

2.3. Sampling and Measurements

2.3.1. Faba Bean Production Measurement

Two randomly selected rows, excluding edge rows and a 1 m boundary at the end of each row, were sampled and measured. Aboveground plant parts were harvested and divided into grain and straw and oven-dried at 65 °C to constant weight to measure grain yield, aboveground biomass, and hundred-kernel weight. Grain yield and aboveground biomass were determined per unit land area on a dry mass basis. The harvest index was calculated as the ratio of grain yield to aboveground biomass [9].

2.3.2. Soil Temperature and Water Measurement

Over the four growing seasons, soil temperature was measured hourly using a temperature logger (DS1923). Sensors were placed centrally between two plants within planting rows in each plot at 10 cm soil depth. Daily mean soil temperature was calculated as the average of the 24 recorded values. Soil samples for gravimetrical water content (%) measurement were collected at 0.2 m intervals to 2 m depth at the end of each growing season. One core per plot was taken randomly and centrally between two plants in the furrow or planting row using a soil auger (4 cm diameter and 20 cm height). Fresh soil samples were weighed and oven-dried at 105 °C to constant weight for gravimetric water content determination. Soil bulk density was determined using the cutting ring method and used to calculate soil water storage (SWS, mm) [8,14]:
SWS (mm) = soil water content (%) × soil bulk density (g cm−3) × soil depth (mm)

2.3.3. Root Nodule Weight Measurement

During the flowering and pod formation stage each year, three randomly selected plants in each plot were sampled to collect root nodules, which were oven-dried at 65 °C to constant weight to determine nodule dry weight per plant.

2.3.4. Soil Biochemical Properties

Soil samples from planting rows, comprising three randomly selected sub-samples (each 4 cm in diameter and 20 cm in depth), were passed through a 2 mm mesh sieve to remove plant debris, root fragments, and stones. The soil samples were divided into two parts: one stored at 4 °C for measurements of soil available N (NH4+-N + NO3−-N), microbial biomass C (MBC), and microbial biomass N (MBN), and the other was air-dried for soil available P, organic C, total N, and total P determination. Soil organic C, total N, total P, and available P were measured at the faba bean maturity stage each year. Soil available N, MBC, and MBN were determined at the seedling, bud branching, flowering and pod formation, and maturity stages from 2021 to 2023. Soil available N was analyzed using an auto-flow injection system (SEAL-AA3, Bran+Luebbe, Hamburg, Germany) after extraction in 2 M KCl and shaking at 200 rpm for 1 h [16]. Soil MBC and MBN were measured using the fumigation–extraction method [12]. Briefly, 20 g fresh soil samples were fumigated at 25 °C for 24 h. Total organic C and total N were extracted from the chloroform-fumigated and non-fumigated soil samples with 0.5 mol L−1 K2SO4 (soil/solution ratio of 1:4 w/v) for 1 h. The filtered extracts were analyzed using a TOC analyzer (TOC-L CPH Basic Analyzer System, Shimadzu, Kyoto, Japan). A KEC factor of 0.45 and a KEN factor of 0.54 were used to calculate microbial biomass C and N contents, respectively. Soil available P was determined using the Olsen-P method [25]. Soil organic C was determined using the Walkley and Black dichromate oxidation method [12]. Soil total N was determined using semi-micro-Kjeldahl digestion followed by titration with a diluted sulfuric acid solution [12,29]. The soil C/N ratio was calculated as the ratio of soil organic C and soil total N [11,12]. Soil total P was determined with colorimetric measurement after digestion with HClO4–H2SO4 [29]. All calculations were expressed on an air-dry basis.

2.4. Statistical Analysis

A two-way analysis of variance in randomized blocks was performed at each measurement time to test the effects of film mulching methods and P fertilizer levels on response variables. Significant differences at p ≤ 0.05, p ≤ 0.01, and p ≤ 0.001 were determined for all tests. The least significant difference (LSD) test was used to identify significant differences between treatment means (p ≤ 0.05). Linear regression analysis was used to establish relationships between soil temperature, SWS, nodule dry weight, soil total nitrogen, soil total phosphorus, soil available nitrogen, soil microbial biomass nitrogen, and grain yield across different treatments. Principal component analysis (PCA) using CANOCO 5.0 software was performed to determine interrelationships among the various parameters studied. All reported determinations are the means of three replicates. Statistical analyses were performed using GenStat 23rd edition (VSN International Ltd., Rothamsted, UK) with graphs created in Origin 9.8 (OriginLab OriginPro 2021, USA).

3. Results

3.1. Grain Yield and Aboveground Biomass

Grain yield and aboveground biomass gradually decreased from 2020 to 2023, with significantly higher values in NMF than DRM and TRM (Figure 2). The NMF treatment had the highest annual mean grain yield (2273 kg ha−1), followed by TRM (1030 kg ha−1) and DRM (943 kg ha−1). In the P0 and P1 treatments, TRM had significantly higher grain yield and aboveground biomass than DRM. However, the reverse was true in the P2 treatment. Grain yield in all years and aboveground biomass in 2020, 2021, and 2023 increased with increasing P levels in NMF and DRM but decreased in TRM. The NMF treatment had a significantly higher harvest index and hundred-kernel weight in 2020, 2022, and 2023 than DRM and TRM. In the P0 and P1 treatments, TRM had a significantly higher or similar harvest index and hundred-kernel weight than DRM but lower values in the P2 treatment. The increasing P levels increased the harvest index (2020–2022) and hundred-kernel weight (2020–2023) in NMF and DRM but decreased these values in TRM.

3.2. Soil Temperature Dynamics

Figure 3 and Figure 4 show the effects of film mulching methods and P levels on daily soil temperatures. The ridges and furrows mulched treatments (DRM and TRM) consistently exhibited higher daily soil temperatures than NMF across the three P levels in the 2021–2023 growing seasons. Moreover, TRM had slightly higher daily soil temperatures than DRM. The daily soil temperature increase as a result of DRM and TRM gradually decreased along with the growing seasons relative to NMF. Daily soil temperature differed little among the three P levels. Film mulching methods significantly affected the average soil temperature during the 2021–2023 growing seasons (Table 1). Specifically, DRM and TRM increased the average soil temperature across the growing season by 2.71 °C and 2.81 °C in 2021, 3.17 °C and 3.94 °C in 2022, and 3.33 °C and 3.56 °C in 2023, respectively, relative to NMF. In other words, DRM and TRM increased the average soil temperature during the growing season by 16.1–20.5% and 16.7–23.0%, respectively.

3.3. Soil Water Content and Storage

From 2020 to 2023, NMF had the lowest soil water content (SWC) in the 0–2 m soil profile compared to DRM and TRM, except for P0 in 2020 (Figure 5). In the P0 and P1 treatments, DRM had a similar or higher SWC than TRM, but in the P2 treatment, DRM had a similar or lower SWC than TRM. In NMF and DRM, the SWC in the 0–2 m soil profile decreased with increasing P level, but the opposite was true for TRM (Figure 6). Due to higher precipitation in August 2022 (Figure 1), the deeper soil profile had a higher SWC at the faba bean maturity stage than the other years, especially in DRM and TRM (Figure 5 and Figure 6), while the upper soil profile had a lower SWC at the faba bean maturity stage in 2023 than the other years, especially in NMF.
The NMF treatment had lower SWS in the 0–1 m, 1–2 m, and 0–2 m soil layers than DRM and TRM from 2020 to 2023 (Figure 7). In the 0–1 m and 0–2 m soil layers, DRM had higher SWS than TRM in the P0 and P1 treatments but lower SWS in the P2 treatment. In the 1–2 m soil layer, the P2 treatment in TRM had the highest SWS, and the P2 treatment in DRM had the lowest SWS across all film mulching treatments. The SWS in the 0–1 m, 1–2 m, and 0–2 m soil layers gradually decreased with increasing P levels in NMF and DRM but gradually increased with increasing P levels in TRM. The 2022 growing season exhibited higher SWS in the 1–2 m soil profile than the other years, especially in DRM and TRM.

3.4. Root Nodule Weight per Plant

From 2020 to 2023, NMF had significantly higher nodule dry weight per plant than DRM and TRM, especially in the P1 and P2 treatments (Table 2). For the P0 and P1 treatments, TRM had higher nodule dry weight per plant than DRM, except in the P1 treatment in 2022. However, in the P2 treatment, TRM had lower nodule dry weight per plant than DRM. Nodule dry weight per plant increased with increasing P levels in NMF and DRM but decreased with increasing P levels in TRM. Like grain yield and aboveground biomass, nodule dry weight per plant decreased with increasing planting years.

3.5. Soil Biochemical Properties

Soil organic carbon was ranked TRM > NMF > DRM, except for similar values for NMF and DRM in 2022 (Figure 8). The average SOC values from 2020 to 2023 were 13.93, 11.88, and 11.26 g kg−1 in TRM, NMF, and DRM, respectively. The NMF treatment had a significantly higher total N than DRM and TRM (Figure 8). In the P0 and P1 treatments, TRM had a similar or higher total N than DRM but a similar or lower total N in the P2 treatment. The DRM and TRM treatments had significantly higher soil C/N ratios than NMF, with TRM treatment significantly higher than DRM (Figure 8). The average soil C/N ratio from 2020 to 2023 increased by 10.00% in DRM and 26.91% in TRM relative to NMF. SOC, total N, and the soil C/N ratio increased with increasing P levels in NMF and DRM but decreased with increasing P levels in TRM. In 2020 and 2023, TRM had significantly higher total P than NMF and DRM (Figure 8). In 2020, NMF had soil available P similar to TRM and significantly higher than DRM. In 2022 and 2023, NMF had significantly higher soil available P than DRM and TRM (Figure 8). Total P and soil available P increased significantly with increasing P levels, except for total P in 2020. From 2020 to 2023, the DRM and TRM treatments had 8.21% and 11.5% lower average soil available P for P0, P1, and P2 than NMF. The P1 and P2 treatments had 29.9% and 43.9% higher average soil available P for NMF, DRM, and TRM than P0.
Film mulching method and P level significantly affected soil available N content, which varied with growth stage (Figure 9). The NMF treatment had the highest soil available N at the seedling and bud branching stages in 2021, 2022, and 2023, and flowering and pod formation stage in 2021, while TRM had the highest values at the maturity stage in 2021 and the flowering and pod formation and maturity stages in 2022 and 2023. Soil available N increased with increasing P levels in NMF and DRM but decreased with increasing P levels in TRM.
The NMF treatment had significantly higher soil MBC than DRM and TRM, except for the bud branching stage in 2022 (Figure 10). In the P0 and P1 treatments, TRM had similar or higher soil MBC than DRM but similar or lower soil MBC than DRM in the P2 treatment. Soil MBC increased with increasing P levels in NMF and DRM while decreasing with increasing P levels in TRM. Film mulching method and P level significantly affected soil MBN, which varied with growth stage (Figure 10). At the seedling stage in 2021 and 2022 and the seedling and bud branching stages in 2023, NMF had significantly higher soil MBN than DRM and TRM. The DRM or TRM treatment had the highest soil MBN at the bud branching, flowering and pod formation, and maturity stages in 2021, bud branching and maturity stages in 2022, and flowering and pod formation and maturity stages in 2023. At the seedling and bud branching stages, soil MBN decreased with increasing P levels in NMF and DRM but increased with increasing P levels in TRM. At the flowering and pod formation and maturity stages, soil MBN increased with increasing P levels in NMF and DRM but decreased with increasing P levels in TRM.

3.6. Relationships between Faba Bean Grain Yield, Soil Water Storage and Temperature, Nodule Dry Weight, and Soil Biochemical Properties

The PCA revealed the relationships between grain yield, SWS, soil temperature, nodule dry weight, and soil biochemical properties (Figure 11). The first two PCA axes accounted for 49.96% and 29.22% of the variation. Grain yield and nodule dry weight appeared on the left of the horizontal axis, while total P appeared on the right. Soil available N, soil temperature, SWS, and MBN appeared on the bottom of the vertical axis, and total N appeared on the top. The NMF treatment was associated with the highest grain yields, nodule dry weights, and total N and soil N availability, while DRM and TRM had more positive effects on total P, soil temperature, SWS, and MBN.
Grain yield negatively correlated with soil temperature, SWS, and soil total P and positively correlated with nodule dry weight and soil total N (Figure 12). Grain yield positively correlated with soil available N and negatively correlated with soil MBN at the seedling stage (Figure 13). No significant correlations occurred between grain yield and soil available N or soil MBN at the maturity stage.

4. Discussion

4.1. Soil Temperature and Water

In this study, film mulching treatments (DRM and TRM) produced higher soil temperatures than NMF across the entire growing season, consistent with a previous study by Luo et al. [14] on the semi-arid eastern African Plateau. A significant warming effect of plastic film mulching with ridges and furrows occurred during the early growth stages of faba bean when canopies were small and solar radiation could penetrate the canopy to warm the topsoil beneath the film, as reported by Zhang et al. [1] and Wang et al. [13]. As plants grew, the warming effect of solar radiation on topsoil decreased due to the increased canopy size and shading [2], mirroring the reduced warming effect of plastic film mulching with faba bean growth in our study. However, concerns exist about the adaptability of plastic film mulching in alpine regions with low air temperatures and strong solar radiation. Higher soil temperature during later crop growth stages could accelerate crop senescence due to heat stress, reduce crop water and nutrient use, shorten reproductive growth periods, and decrease photosynthate transport to seeds, decreasing crop yield [6]. In this study, the NMF treatment had lower soil temperature, higher grain yield, and more aboveground biomass than the other treatments, indicating that lower soil temperature may benefit faba bean yield formation, alleviating the effect of soil temperature stress on water and nutrient uptake and delaying crop senescence, as suggested by Quan et al. [10]. The grain yield increase under the NMF treatment condition was closely related to a significant increase in hundred-kernel weight. Hu et al. [6] showed that the increase in hundred-kernel weight could be attributed partly to delayed leaf senescence and increased leaf photosynthetic rate during the grain-filling stage. Therefore, the higher hundred-kernel weight under the NMF treatment condition might be due to relatively high leaf areas and photosynthetic capacity, promoting grain filling during later growth stages compared to DRM and TRM.
In arid and semi-arid regions where severe water deficits and low temperatures limit agricultural productivity, plastic film mulching has been shown to increase soil temperature, reduce soil evaporation, improve water harvesting efficiency, and thus enhance crop productivity compared to no film mulching [6,10,14,17]. However, our study revealed that despite the increased soil temperature and soil water content under plastic film mulching, faba bean grain yield and aboveground biomass did not surpass those in the NMF treatment. In other words, soil water and temperature conditions may not be the primary limiting factors affecting faba bean production under plastic film mulching and P fertilization in this alpine and semi-arid agricultural setting. The NMF treatment exhibited lower soil water content and SWS than plastic film mulching. This finding is likely due to NMF increasing ineffective soil water evaporation and elevating soil water consumption through transpiration, as faba bean plants extract water to increase grain yield and aboveground biomass [10]. Moreover, plastic film mulching increased soil water in the 1–2 m soil profile during the maturity stage in 2022 compared to the NMF treatment, primarily due to high precipitation during that period.

4.2. Soil Organic Carbon and Total Nitrogen

Plastic film mulching had little effect on SOC content compared to no film mulching, possibly due to the balance between the increased C input from crop residues and accelerated soil C decomposition [12,30]. Some studies have reported positive impacts of plastic film mulching on SOC due to greater crop growth enhancements and crop root and litter residues returned to the soil than SOC outputs through soil microbial decomposition [31,32]. Decreased SOC content under plastic film mulching has also been reported, where SOC losses exceeded C inputs, adversely affecting soil fertility and sustainability [11,18,33]. These variable responses of SOC to plastic film mulching are mainly due to the balance between SOC loss and accumulation, varying among crop types, agricultural systems, and management practices [32]. Soil MBC is a key indicator of soil microbial activity and is crucial in regulating SOC decomposition. Soil hydrothermal conditions, particularly moisture and temperature, significantly influence these dynamics [11,12,33]. In this study, film mulching treatments exhibited higher soil moisture, temperature, and SOC than the NMF treatment, whereas MBC and faba bean growth followed the opposite trend. The increased faba bean growth under the NMF treatment condition enhanced microbial biomass substrates, leading to rapid SOC decomposition and reduced SOC content. The soil C/N ratio may indicate SOC decomposition rates, with a lower C/N ratio accelerating biodegradation [12,34]. The higher soil C/N ratio under film mulching treatments compared to the NMF treatment slowed SOC decomposition, increasing SOC content.
Phosphorus application accelerated active C utilization, restrained passive C decomposition, and helped create a long-term stable C sink [23]. However, the effects on litter decomposition rates may not always result in a net increase in C storage [28,35]. In this study, the changing patterns of SOC and P levels differed between planting modes, increasing in NMF and DRM and decreasing in TRM. In NMF and DRM, P fertilization promoted faba bean growth and soil MBC, with the increased crop residues returned to the soil likely surpassing SOC decomposition by soil microbes, increasing SOC with increasing P level. However, in TRM, P fertilization decreased faba bean growth and soil MBC, with the SOC loss due to soil microbial decomposition potentially exceeding C inputs, decreasing SOC with increasing P levels.
The NMF treatment had higher nodule dry weight than the film mulching treatments. However, the increasing P levels increased nodule dry weight in NMF and DRM and decreased nodule dry weight in TRM, which may influence the corresponding soil total N content. However, when soil total N is <2 g kg−1, soil is generally considered very deficient in total N [11]. In this study, soil total N across all treatments ranged from 0.74 to 1.23 g kg−1, indicating that the soil was very poor in total N.

4.3. Soil N and P Availability

The average soil available P content from 2020 to 2023 indicated sufficient P availability for faba bean production, with values ranging from 18.7 to 26.9 mg kg−1, respectively, similar to or higher than the critical Olsen-P level (20 mg kg−1) recommended for major crop production in China [36,37]. Meanwhile, the P0 treatment had 4.2 times higher average soil available P content than the background value (4.51 mg kg−1). These findings indicate that faba bean cultivation efficiently increased soil P availability. However, P application also intensified soil microbial N limitation [23,38].
Soil N availability is associated with SOC dynamics, where low soil N availability can promote microbial SOC decomposition for N acquisition (microbial N mining theory) [28,33,39,40]. In this study, the rapid SOC decomposition under the NMF treatment condition might have increased soil N availability during early growth stages. The lower soil temperature and reduced soil N consumption during early growth under the NMF treatment condition prevented premature crop senescence and increased faba bean yield [10]. Film mulching treatments exhibited slower SOC decomposition due to a higher soil C/N ratio, resulting in lower soil N availability during early growth stages. The lower soil N availability under film mulching treatments during early growth stages might be a crucial factor contributing to the reduced faba bean yield compared to NMF. However, during later growth stages, poor faba bean growth under film mulching treatments reduced soil N requirements and uptake, leading to a higher soil available N content [16]. Thus, faba bean grain yield positively correlated with soil available N at the seedling stage but did not correlate with soil available N at the maturity stage. It is worth noting that the high-level soil available N content under film mulching treatments at later growth stages might increase the risk of N leaching. Additionally, plants under the NMF treatment condition require N fertilizer to increase faba bean grain yield and avoid mineralizing the soil for available N.
Faba bean grain yield negatively correlated with soil MBN, especially at the seedling stage. This negative correlation may be attributed to higher substrate affinities, faster growth rates, and larger surface area to volume ratios of soil microbes compared to plants, enabling them to outcompete plants for N [41]. In NMF and DRM, P fertilization increased soil available N and decreased soil MBN during early growth stages, benefiting faba bean N uptake and increasing grain yield with increasing P level. However, in TRM, P fertilization decreased soil available N and increased soil MBN during early growth stages, intensifying the competition for available N between soil microbes and faba bean and thus decreasing grain yield with increasing P level. Apart from soil N availability, competition with soil microbes is a critical factor influencing a plant’s ability to acquire N from the soil [41].
The PCA integrated evaluation showed that NMF improved faba bean grain yield, nodule dry weight, and soil total N compared to film mulching treatments (DRM and TRM). The film mulching treatments also had higher soil temperatures and SWS than NMF. Moreover, faba bean grain yield negatively correlated with soil total P and did not correlate with soil available P but positively correlated with soil total N and available N. These findings indicate that faba bean grain yield improvement was not associated with changes in soil hydrothermal conditions, soil P supply, or soil P availability but was directly related to soil N supply and soil N availability.
While plastic film mulching can significantly enhance crop yield and aboveground biomass, especially in arid and semi-arid regions [1,10,14,29], its effectiveness depends on factors such as growing season precipitation and crop type [15]. Zhang et al. [7] reported that the most suitable areas for plastic film mulching are those with about 300–600 mm precipitation and 3–9 °C air temperatures, with yields increasing as precipitation and temperature decreased. In this study, despite increased soil water and temperature efficiency, faba bean grain yield and aboveground biomass were more sensitive to changes in soil total N, nodule dry weight, and soil available N than soil water and temperature. The film mulching treatments not only decreased faba bean grain yield and aboveground biomass but also increased inputs, including material costs of plastic film, labor, and potential environmental pollution from microplastics, phthalates, and agrochemicals, with an increased risk of N leaching during later growth stages [10,14,15,34]. Hence, plastic film mulching combined with P fertilization may not be optimal for faba bean production in semi-arid and alpine agricultural regions due to inadequate soil N supply, limited soil N availability during early growth stages, and reduced grain yield. Moreover, soil N availability significantly influences microbial activity and synthesis of extracellular enzymes, processes that can drive SOC decomposition [39]. Changes in soil microbial community composition can further influence the decomposition of various SOC fractions [23]. Therefore, investigating the effects of plastic film mulching and P fertilization on soil extracellular enzymes and microbial community composition emerges as a new scientific inquiry to better understand the underlying mechanisms governing soil N availability and SOC dynamics.

5. Conclusions

This study provides insights into suitable planting modes for faba bean production under different film mulching regimes and P levels in the semi-arid and alpine eastern agriculture area of Qinghai Province. We found that NMF improved faba bean grain yield, nodule weight, and soil total N content and increased soil N availability and MBN during early growth stages compared to film mulching treatments but decreased soil water and temperature conditions, the soil C/N ratio, and SOC content. Changes in grain yield, nodule weight, SOC, total N, the soil C/N ratio, soil available N, and MBC with increasing P levels differed between planting modes, increasing in NMF and DRM and decreasing in TRM. Moreover, P fertilization decreased soil MBN during early growth stages, soil water content, and SWS in NMF and DRM but increased soil MBN during early growth stages, soil water content, and SWS in TRM. Soil total P and available P contents increased with increasing P levels. We conclude that NMF combined with P fertilizer (~18.2 kg P ha−1) is a reasonable agronomic management practice to enhance faba bean productivity in the local area. However, appropriate N fertilizer application is recommended to maintain soil fertility and reduce SOC decomposition for N acquisition.

Author Contributions

Conceptualization, Y.G.; Formal analysis, Y.G.; Funding acquisition, Y.G.; Investigation, Q.X. and W.Z.; Methodology, C.H.; Project administration, Y.G.; Resources, C.H.; Supervision, C.H.; Writing—original draft, Y.G.; Writing—review and editing, K.H.M.S. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Science and Technology Project of Qinghai Province [No. 2020-ZJ-969Q], and the National Natural Science Foundation of China [No. 31960625]. The APC was funded by the National Natural Science Foundation of China [No. 31960625].

Data Availability Statement

Data are contained within the article.

Acknowledgments

We also thank the editors and anonymous reviewers for their valuable comments and suggestions on the manuscript.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Zhang, X.D.; Yang, L.C.; Xue, X.K.; Kamran, M.; Ahmad, I.; Dong, Z.Y.; Liu, T.N.; Jia, Z.K.; Zhang, P.; Han, Q.F. Plastic film mulching stimulates soil wet-dry alternation and stomatal behavior to improve maize yield and resource use efficiency in a semi-arid region. Field Crops Res. 2019, 233, 101–113. [Google Scholar] [CrossRef]
  2. Kong, M.; Jia, Y.; Gu, Y.J.; Han, C.L.; Song, X.; Shi, X.Y.; Siddique, K.H.M.; Zdruli, P.; Zhang, F.; Li, F.M. How film mulch increases the corn yield by improving the soil moisture and temperature in the early growing period in a cool, semi-arid area. Agronomy 2020, 10, 1195. [Google Scholar] [CrossRef]
  3. Hou, W.W.; Zhang, X.J.; Yan, Q.B.; Li, P.; Sha, W.C.; Tian, Y.Y.; Liu, Y.J. Linkage map of a gene controlling zero tannins (zt-1) in faba bean (Vicia faba L.) with SSR and ISSR markers. Agronomy 2018, 8, 80. [Google Scholar] [CrossRef]
  4. Li, P.; Zhang, Y.X.; Wu, X.X.; Liu, Y.J. Drought stress impact on leaf proteome variations of faba bean (Vicia faba L.) in the Qinghai-Tibet Plateau of China. 3 Biotech 2018, 8, 110. [Google Scholar] [CrossRef]
  5. Stoddard, F.L.; Hovinen, S.; Kontturi, M.; Lindström, K.; Nykänen, A. Legumes in Finnish agriculture: History, present status and future prospects. Agric. Food Sci. 2009, 18, 191–205. [Google Scholar] [CrossRef]
  6. Hu, Y.J.; Ma, P.H.; Duan, C.X.; Wu, S.F.; Feng, H.; Zou, Y.F. Black plastic film combined with straw mulching delays senescence and increases summer maize yield in northwest China. Agric. Water Manag. 2020, 231, 106031. [Google Scholar] [CrossRef]
  7. Zhang, F.; Zhang, W.J.; Qi, J.G.; Li, F.M. A regional evaluation of plastic film mulching for improving crop yields on the Loess Plateau of China. Agric. For. Meteorol. 2018, 248, 458–468. [Google Scholar] [CrossRef]
  8. Li, M.; Zhang, K.P.; Eldoma, I.M.; Fang, Y.J.; Zhang, F. Plastic film mulching sustains high maize (Zea mays L.) grain yield and maintains soil water balance in semiarid environment. Agronomy 2020, 10, 600. [Google Scholar] [CrossRef]
  9. Li, C.; Wang, Q.S.; Wang, N.J.; Luo, X.Q.; Li, Y.; Zhang, T.B.; Feng, H.; Dong, Q.G. Effects of different plastic film mulching on soil hydrothermal conditions and grain-filling process in an arid irrigation district. Sci. Total Environ. 2021, 795, 148886. [Google Scholar] [CrossRef] [PubMed]
  10. Quan, H.; Feng, H.; Zhang, T.B.; Wu, L.H.; Dong, Q.G.; Siddique, K.H.M. Response of soil water, temperature, and maize productivity to different irrigation practices in an arid region. Soil Till. Res. 2024, 237, 105962. [Google Scholar] [CrossRef]
  11. Zhou, L.M.; Jin, S.L.; Liu, C.A.; Xiong, Y.C.; Si, J.T.; Li, X.G.; Gan, Y.T.; Li, F.M. Ridge-furrow and plastic-mulching tillage enhances maize–soil interactions: Opportunities and challenges in a semiarid agroecosystem. Field Crops Res. 2012, 126, 181–188. [Google Scholar] [CrossRef]
  12. Dong, Q.G.; Yang, Y.C.; Yu, K.; Feng, H. Effects of straw mulching and plastic film mulching on improving soil organic carbon and nitrogen fractions, crop yield and water use efficiency in the Loess Plateau, China. Agric. Water Manag. 2018, 201, 133–143. [Google Scholar] [CrossRef]
  13. Wang, X.K.; Li, Z.B.; Xing, Y.Y. Effects of mulching and nitrogen on soil temperature, water content, nitrate-N content and maize yield in the Loess Plateau of China. Agric. Water Manag. 2015, 161, 53–64. [Google Scholar]
  14. Luo, C.L.; Zhang, X.F.; Duan, H.X.; Zhou, R.; Mo, F.; Mburu, D.M.; Wang, B.Z.; Wang, W.; Kavagi, L.; Xiong, Y.C. Responses of rainfed wheat productivity to varying ridge-furrow size and ratio in semiarid eastern African Plateau. Agric. Water Manag. 2021, 249, 106813. [Google Scholar] [CrossRef]
  15. Gan, Y.T.; Siddique, K.H.M.; Turner, N.C.; Li, X.G.; Niu, J.Y.; Yang, C.; Liu, L.P.; Chai, Q. Ridge-furrow mulching systems—An innovative technique for boosting crop productivity in semiarid rain-fed environments. Adv. Agron. 2013, 118, 429–476. [Google Scholar]
  16. Jiang, R.; Li, X.; Zhu, W.; Wang, K.; Guo, S.; Misselbrook, T.; Hatano, R. Effects of the ridge mulched system on soil water and inorganic nitrogen distribution in the Loess Plateau of China. Agric. Water Manag. 2018, 203, 277–288. [Google Scholar] [CrossRef]
  17. Gu, Y.J.; Han, C.L.; Fan, J.W.; Shi, X.P.; Kong, M.; Shi, X.Y.; Siddique, K.H.M.; Zhao, Y.Y.; Li, F.M. Alfalfa forage yield, soil water and P availability in response to plastic film mulch and P fertilization in a semiarid environment. Field Crops Res. 2018, 215, 94–103. [Google Scholar] [CrossRef]
  18. Li, F.M.; Song, Q.H.; Jjemba, P.K.; Shi, Y.C. Dynamics of soil microbial biomass C and soil fertility in cropland mulched with plastic film in a semiarid agro-ecosystem. Soil Biol. Biochem. 2004, 36, 1893–1902. [Google Scholar] [CrossRef]
  19. Vitousek, P.M.; Porder, S.; Houlton, B.Z.; Chadwick, O.A. Terrestrial phosphorus limitation: Mechanisms, implications, and nitrogen—Phosphorus interactions. Ecol. Appl. 2010, 20, 5–15. [Google Scholar] [CrossRef]
  20. Momen, A.; Koocheki, A.; Mahallati, M.N. Analysis of the variations in dry matter yield and resource use efficiency of maize under different rates of nitrogen, phosphorous and water supply. J. Plant Nutr. 2020, 43, 1306–1319. [Google Scholar] [CrossRef]
  21. Fan, J.W.; Du, Y.L.; Wang, B.R.; Turner, N.C.; Wang, T.; Abbott, L.K.; Stefanova, K.; Siddique, K.H.M.; Li, F.M. Forage yield, soil water depletion, shoot nitrogen and phosphorus uptake and concentration, of young and old stands of alfalfa in response to nitrogen and phosphorus fertilisation in a semiarid environment. Field Crops Res. 2016, 198, 247–257. [Google Scholar] [CrossRef]
  22. He, H.H.; Wu, M.M.; Guo, L.; Fan, C.B.; Zhang, Z.K.; Su, R.; Peng, Q.; Pang, J.Y.; Lambers, H. Release of tartrate as a major carboxylate by alfalfa (Medicago sativa L.) under phosphorus deficiency and the effect of soil nitrogen supply. Plant Soil 2020, 449, 169–178. [Google Scholar] [CrossRef]
  23. Shi, J.Y.; Gong, J.R.; Li, X.B.; Zhang, Z.H.; Zhang, W.Y.; Li, Y.; Song, L.Y.; Zhang, S.Q.; Dong, J.J.; Baoyin, T.T. Plant–microbial linkages regulate soil organic carbon dynamics under phosphorus application in a typical temperate grassland in northern China. Agric. Ecosyst. Environ. 2022, 335, 108006. [Google Scholar] [CrossRef]
  24. Simpson, R.J.; Oberson, A.; Culvenor, R.A.; Ryan, M.H.; Veneklaas, E.J.; Lambers, H.; Lynch, J.P.; Ryan, P.R.; Delhaize, E.; Smith, F.A.; et al. Strategies and agronomic interventions to improve the phosphorus-use efficiency of farming systems. Plant Soil 2011, 349, 89–120. [Google Scholar] [CrossRef]
  25. Cheng, Y.; Wang, J.; Sun, N.; Xu, M.G.; Zhang, J.B.; Cai, Z.C.; Wang, S.Q. Phosphorus addition enhances gross microbial N cycling in phosphorus-poor soils: A 15N study from two long-term fertilization experiments. Biol. Fertil. Soils 2018, 54, 783–789. [Google Scholar] [CrossRef]
  26. Zhong, Z.K.; Li, W.J.; Lu, X.Q.; Gu, Y.Q.; Wu, S.J.; Shen, Z.Y.; Han, X.H.; Yang, G.H.; Ren, C.J. Adaptive pathways of soil microorganisms to stoichiometric imbalances regulate microbial respiration following afforestation in the Loess Plateau, China. Soil Biol. Biochem. 2020, 151, 108048. [Google Scholar] [CrossRef]
  27. Mehnaz, K.R.; Corneo, P.E.; Keitel, C.; Dijkstra, F.A. Carbon and phosphorus addition effects on microbial carbon use efficiency, soil organic matter priming, gross nitrogen mineralization and nitrous oxide emission from soil. Soil Biol. Biochem. 2019, 134, 175–186. [Google Scholar] [CrossRef]
  28. Poeplau, C.; Bolinder, M.A.; Kirchmann, H.; Kätterer, T. Phosphorus fertilisation under nitrogen limitation can deplete soil carbon stocks: Evidence from Swedish meta-replicated long-term field experiments. Biogeosciences 2016, 13, 1119–1127. [Google Scholar] [CrossRef]
  29. Gu, Y.J.; Han, C.L.; Kong, M.; Shi, X.Y.; Zdruli, P.; Li, F.M. Plastic film mulch promotes high alfalfa production with phosphorus-saving and low risk of soil nitrogen loss. Field Crops Res. 2018, 229, 44–54. [Google Scholar] [CrossRef]
  30. Zhang, F.; Zhang, W.J.; Li, M.; Zhang, Y.; Li, F.M.; Li, C.B. Is crop biomass and soil carbon storage sustainable with long-term application of full plastic film mulching under future climate change? Agric. Syst. 2017, 150, 67–77. [Google Scholar] [CrossRef]
  31. Wang, J.; Fu, X.; Zhao, F.Z.; Sainju, U.M. Response of soil carbon fractions and dryland maize yield to mulching. Soil Sci. Soc. Am. J. 2018, 82, 371–381. [Google Scholar] [CrossRef]
  32. Yu, Y.X.; Zhang, Y.X.; Xiao, M.; Zhao, C.Y.; Yao, H.Y. A meta-analysis of film mulching cultivation effects on soil organic carbon and soil greenhouse gas fluxes. Catena 2021, 206, 105483. [Google Scholar] [CrossRef]
  33. Zhang, K.P.; Li, Z.X.; Li, Y.F.; Wan, P.X.; Chai, N.; Li, M.; Wei, H.H.; Kuzyakov, Y.; Filimonenko, E.; Almwarai Alharbi, S.; et al. Contrasting impacts of plastic film mulching and nitrogen fertilization on soil organic matter turnover. Geoderma 2023, 440, 116714. [Google Scholar] [CrossRef]
  34. Steinmetz, Z.; Wollmann, C.; Schaefer, M.; Buchmann, C.; David, J.; Tröger, J.; Muñoz, K.; Frör, O.; Schaumann, G.E. Plastic mulching in agriculture. Trading short-term agronomic benefits for long-term soil degradation? Sci. Total Environ. 2016, 550, 690–705. [Google Scholar] [CrossRef] [PubMed]
  35. Cleveland, C.C.; Townsend, A.R. Nutrient additions to a tropical rain forest drive substantial soil carbon dioxide losses to the atmosphere. Proc. Natl. Acad. Sci. USA 2006, 103, 10316–10321. [Google Scholar] [CrossRef] [PubMed]
  36. Bai, Z.H.; Li, H.G.; Yang, X.Y.; Zhou, B.K.; Shi, X.J.; Wang, B.R.; Li, D.C.; Shen, J.B.; Chen, Q.; Qin, W.; et al. The critical soil P levels for crop yield, soil fertility and environmental safety in different soil types. Plant Soil 2013, 372, 27–37. [Google Scholar] [CrossRef]
  37. Li, H.G.; Huang, G.; Meng, Q.Y.; Ma, L.N.; Yuan, L.X.; Wang, F.; Zhang, W.; Cui, Z.; Shen, J.; Chen, X.; et al. Integrated soil and plant phosphorus management for crop and environment in China. A review. Plant Soil 2011, 349, 157–167. [Google Scholar] [CrossRef]
  38. Huang, J.S.; Hu, B.; Qi, K.B.; Chen, W.J.; Pang, X.Y.; Bao, W.K.; Tian, G.L. Effects of phosphorus addition on soil microbial biomass and community composition in a subalpine spruce plantation. Eur. J. Soil Biol. 2016, 72, 35–41. [Google Scholar] [CrossRef]
  39. Maslov, M.N.; Maslova, O.A. Nitrogen limitation of microbial activity in alpine tundra soils along an environmental gradient: Intra-seasonal variations and effect of rising temperature. Soil Biol. Biochem. 2021, 156, 108234. [Google Scholar] [CrossRef]
  40. Chen, R.R.; Senbayram, M.; Blagodatsky, S.; Myachina, O.; Dittert, K.; Lin, X.G.; Blagodatskaya, E.; Kuzyakov, Y. Soil C and N availability determine the priming effect: Microbial N mining and stoichiometric decomposition theories. Glob. Chang. Biol. 2014, 20, 2356–2367. [Google Scholar] [CrossRef]
  41. Inselsbacher, E.; Hinko-Najera Umana, N.; Stange, F.C.; Gorfer, M.; Schüller, E.; Ripka, K.; Zechmeister-Boltenstern, S.; Hood-Novotny, R.; Strauss, J.; Wanek, W. Short-term competition between crop plants and soil microbes for inorganic N fertilizer. Soil Biol. Biochem. 2010, 42, 360–372. [Google Scholar] [CrossRef]
Agronomy 14 00447 g001
Figure 1. Monthly mean precipitation and air temperature from 2020 to 2023, and monthly mean precipitation from 1994 to 2023 at the experimental site. The time between the two arrows within each year is the faba bean (Vicia faba L.) growing season.
Figure 1. Monthly mean precipitation and air temperature from 2020 to 2023, and monthly mean precipitation from 1994 to 2023 at the experimental site. The time between the two arrows within each year is the faba bean (Vicia faba L.) growing season.
Agronomy 14 00447 g001
Agronomy 14 00447 g002
Figure 2. Faba bean grain yield (a), aboveground biomass (b), harvest index (c), and hundred-kernel weight (d) in the 2020–2023 growing seasons for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)]. * p ≤ 0.05, ** p ≤ 0.01, and *** p ≤ 0.001. Error bars are standard deviations.
Figure 2. Faba bean grain yield (a), aboveground biomass (b), harvest index (c), and hundred-kernel weight (d) in the 2020–2023 growing seasons for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)]. * p ≤ 0.05, ** p ≤ 0.01, and *** p ≤ 0.001. Error bars are standard deviations.
Agronomy 14 00447 g002
Agronomy 14 00447 g003
Figure 3. Daily soil temperature (10 cm, °C) in the 2021–2023 faba bean growing seasons for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] under three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)]. Increase1 represents the daily soil temperature difference between DRM and NMF, and Increase2 represents the daily soil temperature difference between TRM and NMF.
Figure 3. Daily soil temperature (10 cm, °C) in the 2021–2023 faba bean growing seasons for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] under three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)]. Increase1 represents the daily soil temperature difference between DRM and NMF, and Increase2 represents the daily soil temperature difference between TRM and NMF.
Agronomy 14 00447 g003
Agronomy 14 00447 g004
Figure 4. Daily soil temperature (10 cm, °C) in the 2021–2023 faba bean growing seasons for three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] under three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)].
Figure 4. Daily soil temperature (10 cm, °C) in the 2021–2023 faba bean growing seasons for three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] under three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)].
Agronomy 14 00447 g004
Agronomy 14 00447 g005
Figure 5. Soil water content (SWC, %) profile in 0.2 m increments from 0 to 2 m depth at the faba bean maturity stage from 2020 to 2023 for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] under three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)].
Figure 5. Soil water content (SWC, %) profile in 0.2 m increments from 0 to 2 m depth at the faba bean maturity stage from 2020 to 2023 for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] under three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)].
Agronomy 14 00447 g005
Agronomy 14 00447 g006
Figure 6. Soil water content (SWC, %) profile in 0.2 m increments from 0 to 2 m depth at the faba bean maturity stage from 2020 to 2023 for three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] under three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)].
Figure 6. Soil water content (SWC, %) profile in 0.2 m increments from 0 to 2 m depth at the faba bean maturity stage from 2020 to 2023 for three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] under three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)].
Agronomy 14 00447 g006
Agronomy 14 00447 g007
Figure 7. Soil water storage (SWS, mm) in the upper 1 m, 1–2 m, and 0–2 m soil layers for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] during the four-year experiment. Error bars are LSD values (p = 0.05) for significant treatment differences.
Figure 7. Soil water storage (SWS, mm) in the upper 1 m, 1–2 m, and 0–2 m soil layers for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] during the four-year experiment. Error bars are LSD values (p = 0.05) for significant treatment differences.
Agronomy 14 00447 g007
Agronomy 14 00447 g008
Figure 8. Soil organic carbon (a), total nitrogen (b), C/N ratio (c), total phosphorus (d), and available phosphorus (e) for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] during the four-year experiment. * p ≤ 0.05, ** p ≤ 0.01, and *** p ≤ 0.001. Error bars are standard deviations.
Figure 8. Soil organic carbon (a), total nitrogen (b), C/N ratio (c), total phosphorus (d), and available phosphorus (e) for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] during the four-year experiment. * p ≤ 0.05, ** p ≤ 0.01, and *** p ≤ 0.001. Error bars are standard deviations.
Agronomy 14 00447 g008
Agronomy 14 00447 g009
Figure 9. Soil available N at the seedling (I), bud branching (II), flowering and pod formation (III), and maturity (IV) stages for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] from 2021 to 2023. * p ≤ 0.05, ** p ≤ 0.01, and *** p ≤ 0.001. Error bars are standard deviations.
Figure 9. Soil available N at the seedling (I), bud branching (II), flowering and pod formation (III), and maturity (IV) stages for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] from 2021 to 2023. * p ≤ 0.05, ** p ≤ 0.01, and *** p ≤ 0.001. Error bars are standard deviations.
Agronomy 14 00447 g009
Agronomy 14 00447 g010
Figure 10. Soil microbial biomass C and microbial biomass N at the seedling (I), bud branching (II), flowering and pod formation (III), and maturity (IV) stages for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] from 2021 to 2023. Data for soil microbial biomass C and N at the flowering and pod formation stage (III) in 2022 are missing. * p ≤ 0.05, ** p ≤ 0.01, and *** p ≤ 0.001. Error bars are standard deviations.
Figure 10. Soil microbial biomass C and microbial biomass N at the seedling (I), bud branching (II), flowering and pod formation (III), and maturity (IV) stages for three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] from 2021 to 2023. Data for soil microbial biomass C and N at the flowering and pod formation stage (III) in 2022 are missing. * p ≤ 0.05, ** p ≤ 0.01, and *** p ≤ 0.001. Error bars are standard deviations.
Agronomy 14 00447 g010
Agronomy 14 00447 g011
Figure 11. Principal component analysis using faba bean grain yield, soil water storage (SWS) and temperature, nodule dry weight, and soil biochemical properties as variables under three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)]. MBC and MBN represent soil microbial biomass carbon and nitrogen, respectively.
Figure 11. Principal component analysis using faba bean grain yield, soil water storage (SWS) and temperature, nodule dry weight, and soil biochemical properties as variables under three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)]. MBC and MBN represent soil microbial biomass carbon and nitrogen, respectively.
Agronomy 14 00447 g011
Agronomy 14 00447 g012
Figure 12. Relationships between faba bean grain yield and soil temperature, soil water storage, nodule dry weight, soil total nitrogen, and soil total phosphorus under three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)].
Figure 12. Relationships between faba bean grain yield and soil temperature, soil water storage, nodule dry weight, soil total nitrogen, and soil total phosphorus under three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)].
Agronomy 14 00447 g012
Agronomy 14 00447 g013
Figure 13. Relationships between faba bean grain yield and soil available nitrogen and soil microbial biomass nitrogen under three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] at the seedling and maturity stages.
Figure 13. Relationships between faba bean grain yield and soil available nitrogen and soil microbial biomass nitrogen under three mulching treatments [no film mulching with flat planting (NMF), double ridges and furrows mulched with one plastic film (DRM), and three ridges and furrows mulched with one plastic film (TRM)] and three P levels [0 kg P ha−1 (P0), 9.10 kg P ha−1 (P1), and 18.2 kg P ha−1 (P2)] at the seedling and maturity stages.
Agronomy 14 00447 g013
Table 1. Effect of film mulching methods (M) and P levels on the average soil temperature (°C) during the 2021–2023 faba bean growing seasons (mean ± SD, n = 3).
Table 1. Effect of film mulching methods (M) and P levels on the average soil temperature (°C) during the 2021–2023 faba bean growing seasons (mean ± SD, n = 3).
202120222023
NMFP016.63 ± 0.6716.91 ± 1.3315.92 ± 1.06
P116.92 ± 0.0017.27 ± 0.5116.20 ± 0.60
P216.99 ± 0.0417.32 ± 0.4716.64 ± 0.72
DRMP019.66 ± 0.7720.48 ± 1.1819.46 ± 0.17
P119.64 ± 0.5720.59 ± 0.2719.93 ± 0.87
P219.34 ± 0.1519.95 ± 0.6319.35 ± 0.53
TRMP019.43 ± 0.7821.48 ± 0.3320.27 ± 0.16
P119.97 ± 0.0321.27 ± 0.0519.64 ± 0.62
P219.56 ± 0.6320.58 ± 0.0919.54 ± 0.27
LSD0.05 of ANOVA in randomized block design
M(0.49) ***(0.64) ***(0.60) ***
Pn.s.n.s.n.s.
M × Pn.s.n.s.n.s.
*** p ≤ 0.001. n.s. indicates no significant treatment effect. NMF, no film mulching with flat planting; DRM, double ridges and furrows mulched with one plastic film; TRM, three ridges and furrows mulched with one plastic film; P0, 0 kg P ha−1; P1, 9.10 kg P ha−1; P2, 18.2 kg P ha−1.
Table 2. Nodule dry weight per plant for three mulching treatments (M) and three P levels during the four-year experiment (mean ± SD, n = 3).
Table 2. Nodule dry weight per plant for three mulching treatments (M) and three P levels during the four-year experiment (mean ± SD, n = 3).
2020202120222023
NMFP00.863 ± 0.0261.53 ± 0.110.286 ± 0.0530.199 ± 0.034
P11.37 ± 0.121.54 ± 0.120.349 ± 0.150.231 ± 0.011
P21.53 ± 0.381.84 ± 0.190.372 ± 0.0830.295 ± 0.019
DRMP00.871 ± 0.221.37 ± 0.180.189 ± 0.0750.0246 ± 0.013
P10.927 ± 0.261.40 ± 0.0160.334 ± 0.0730.0383 ± 0.018
P21.43 ± 0.0641.65 ± 0.0820.339 ± 0.0770.0840 ± 0.019
TRMP01.05 ± 0.381.50 ± 0.190.275 ± 0.0790.0978 ± 0.0098
P10.996 ± 0.0751.43 ± 0.150.189 ± 0.0210.0843 ± 0.020
P20.782 ± 0.371.40 ± 0.130.107 ± 0.0310.0330 ± 0.011
LSD0.05 of ANOVA in randomized block design
M(0.24) *(0.13) *(0.073) **(0.016) ***
P(0.24) *(0.13) *n.s.(0.016) **
M × P(0.42) *n.s.(0.13) *(0.028) ***
* Numbers in brackets are LSD (p = 0.05) values for significant treatment differences. * p ≤ 0.05, ** p ≤ 0.01, and *** p ≤ 0.001. n.s. indicates no significant treatment effect. NMF, no film mulching with flat planting; DRM, double ridges and furrows mulched with one plastic film; TRM, three ridges and furrows mulched with one plastic film; P0, 0 kg P ha−1; P1, 9.10 kg P ha−1; P2, 18.2 kg P ha−1.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Gu, Y.; Xu, Q.; Zhou, W.; Han, C.; Siddique, K.H.M. Enhancing Faba Bean Yields in Alpine Agricultural Regions: The Impact of Plastic Film Mulching and Phosphorus Fertilization on Soil Dynamics. Agronomy 2024, 14, 447. https://doi.org/10.3390/agronomy14030447

AMA Style

Gu Y, Xu Q, Zhou W, Han C, Siddique KHM. Enhancing Faba Bean Yields in Alpine Agricultural Regions: The Impact of Plastic Film Mulching and Phosphorus Fertilization on Soil Dynamics. Agronomy. 2024; 14(3):447. https://doi.org/10.3390/agronomy14030447

Chicago/Turabian Style

Gu, Yanjie, Qiuyun Xu, Weidi Zhou, Chenglong Han, and Kadambot H. M. Siddique. 2024. "Enhancing Faba Bean Yields in Alpine Agricultural Regions: The Impact of Plastic Film Mulching and Phosphorus Fertilization on Soil Dynamics" Agronomy 14, no. 3: 447. https://doi.org/10.3390/agronomy14030447

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop