Surface Seeding of Wheat: A Sustainable Way towards Climate Resilience Agriculture

Abstract

Conventional tillage (CT)-based agriculture is known to be ecologically indiscreet, economically and environmentally unsustainable, and leads to the degradation of soil and the environment in the Indo-Gangetic Plain (IGP). The surface seeding (SS) method was introduced to manage agro-ecosystems for sustaining productivity and increasing farmers’ profits, while sustaining the natural resources. Here, we conducted a systematic literature review on SS of wheat reported in the IGP, with the aim to cover the concept of SS, its impact on wheat yield, soil properties, and the environment, with the potential benefits and constraints. The major findings are: (i) an SS-based rice–wheat system improves productivity (∼10%) and profitability (20–30%),while employing a lesser amount of irrigation water (15–30%) and energy input (20–25%) compared to a conventional system; (ii) an SS-based system is more adaptive to extreme climatic conditions, reduces the carbon footprint, and increases crop production; (iii) an SS approach enhances soil health by virtue of increased soil organic carbon and improved soil aggregation, as well as soil, water, and energy conservation; (iv) SS consisting of no-tillage with substantial crop residue retention offers an alternative to crop residue burning. Strong policies/legislation are required to encourage SS of wheat, in order to limit residue burning, and provide farmers with carbon credits in exchange for carbon sequestration and reduced greenhouse gas emissions.

1. Introduction

To address the global food exigency, enhanced agricultural production systems must be exercised via the adoption of technology that is economically viable and socially acceptable by 2050. It is likely that the food scarcity problem will be aggravated, due to the rapid degradation of the environment, and substandard options for cropping. Extreme climatic events deteriorate productive capacity, pushing towards greater instability in agricultural production systems (i.e., crop, livestock, fisheries, and forestry). In most of the cultivated soil in India, the soil organic carbon concentration (SOC) is <5 g kg⁻¹, whereas in uncultivated virgin soils it ranges between 15 to 20 g kg⁻¹ [1]. The probable cause of the decline in SOC and soil degradation in cultivated soils is faulty agricultural practices, i.e., excessive soil tillage, intensive mono-cropping systems, and the burning of crop debris [2]. Inadvertently, the fertilizer response ratio dropped from ∼14 during the 1970s Green Revolution to only ∼4 in 2010 [3]. In any government, producing ample food for the growing population, without compromising the soil health and environment, takes precedence over all other policies [4]. Soil degradation adversely affects the processes of food production, which materializes through the interaction of certain biological and physico–chemical properties of the soil. For that reason, a fresh stance is needed apropos of resource management, contingent on local pedoclimatic conditions, not merely to execute the benefits of improved germplasm, but also to counteract the crop yield barriers. To date, zero till is considered as the most fructifying technology for resource conservation in the rice–wheat (RW) systems of the IGP.

Even though the productivity of cereals, such as rice (Oryza sativa), wheat (Triticum aestivum), and maize (Zea mays L.), increased with time, the quantum of increment declined. The underlying culprit is the deterioration of natural resources caused by unscientific methods of resource management, and intensive tillage-based exploitative farming [2]. Rice and wheat are regarded as the basic pillars of the human diet, and millions of south Asian people rely on the RW cropping system for their livelihood, which is currently being practiced over 13.5 million ha [5]. The Green Revolution triggered a quantum increase in the productivity of RW systems, through the introduction of the seeds of high-yielding varieties, irrigation, fertilizer, and a conducive policy environment. In spite of that, recent studies reveal stagnation in productivity growth [6], and long-term experiments validate the latent/quiescent crop yield trends [5]. Soil quality is strictly governed by the tillage practices that negatively affect physical–hydrological soil parameters that are crucial for wheat and rice cultivation [5,7]. The existing policies encourage inappropriate use of land and input [8]; meanwhile, current crop establishment methods result in a decline in fertilizer response ratios. Resource-conserving, production-cost-minimizing, and productivity-maximizing agricultural technologies that actively sustain a healthy environment are, therefore, becoming imperative [9].

Surface seeding (SS) of wheat is one such kind of technology that has the potential to improve crop productivity on a sustainable basis, without causing environmental damage. Compared to existing crop establishment methods, it has certain benefits with respect to crop productivity, soil health, environment, and socio-economic issues (shown in Figure 1), which recuperate the degraded RW cropping system. SS is an alternative planting technique, through which wheat seeds are manually broadcast in a wet field, before or after the rice harvest [10]. It is a simple technology for resource-poor farmers that requires zero capital for machinery or land preparation; still, its use is largely limited to marshy low-lying fields of the eastern IGP where tractors cannot gain access. SS, as applied to the RW systems, has three distinctive features that make it stand out from the rest [11]; first, SS is applied mostly for sowing wheat crop in a double-cropped system, with the preceding rice crop still being vigorously tilled. Second, SS of wheat following rice does not imply increased herbicide dependence, reflecting that puddled rice fields tend to be weed-free at the time of harvest. Third, SS of wheat does not necessarily entail the retention of crop debris as mulch.

The viability of the rice–wheat cropping systems (RWCS) is threatened as a result of challenges posed by phreatic water depletion, plummeting economic returns, and productivity stagnation in south Asia [12,13]. Promoting SS-based management practices, especially the use of improved seeds, optimum fertilization, integrated soil- and crop-management, besides increased investment in agricultural R&D, is the key to a sustainable production system [14]. SS can also capture revenue synergies among prevailing management activities for rural development and sustainable agriculture, which would substantively contribute to attaining the Sustainable Development Goals (SDGs) (Figure 2). Nutrient transformation/mineralization in soil depends on the biological and physico–chemical characteristics, and, by adopting SS, all these traits improve significantly, enhancing crop productivity in return [4,13]. In the light of the increasing popularity of SS among the farmers of the eastern IGP as a resource conservation technology, we compiled this review paper covering the concept of the SS of wheat, environmental impact of its adoption, and the potentials and constraints of SS-based technologies in the IGP of India.

2. Data Extraction

Experiments on SS are relatively scarce, as it is a newer technology, and popularized only in limited districts of eastern Uttar Pradesh and Bihar. The comparison study (

Table 1. Comparative study between surface seeding, conservation agriculture, and conventional agriculture.

Parameters	Conservation Agriculture	Conventional Agriculture	Surface Seeding
Practice	Nominal soil disruption and the surface of the soil is fully covered	Maximal soil disruption and the surface of the soil is fully exposed	Least soil disruption and the surface of the soil is fully covered
Tillage	Minimal or no-tillage operation	Excessive mechanical tillage operation	No-tillage operation
Timeliness	Mechanized operations, ensure timeliness of operations	Operations can be delayed	Timeliness of operations more optimal
Residue management	Residue retention on the soil surface	Residue burning or removal	Surface retention of residues
Use of organics	Use of in-situ organics/composts	Use of ex-situ organics/composts	Use of in-situ organics/composts
Erosion	Wind and water erosion is minimal	Wind and water erosion is maximum	Least wind and soil erosion
Water infiltration	Better water infiltration	Lowest due to clogging of soil pores	The infiltration rate of water is high
Soil physical health	Comparatively good by increasing porosity, water-holding capacity aggregation, and reducing bulk density	Very poor by increasing bulk density, and decreasing porosity, water-holding capacity, and aggregation	Comparatively good by reducing bulk density, and increasing porosity, water-holding capacity, and aggregation
Soil organic matter	Soil organic carbon build-up and worthy C-sequestration rate	Low due to oxidation of organic matter and residue removal	Higher soil organic carbon build-up and C-sequestration rate
Soil biological health	More diverse and healthy biological properties and populations	Poor biological health, and less microbial diversity and activity	Better biological health, and rich in microbial diversity and activity
Weeds	Weeds are troublesome in the initial stages of adoption but decrease with time; residues can aid in weed-growth-suppression	Controls weeds, causes more weed seeds to germinate, and more crop–weed competition in later growth stage	Weeds are troublesome in the initial stages of adoption but decrease with time; residues can aid in weed-growth-suppression/ reduce the weed seed germination, as they are not allowed to come above soil surface
Environmental stress	Additional resilience to stresses, lower yield losses under stress	Poor adaptation to stresses, yield losses greater under stress conditions	Added resilience to stresses, minimum yield losses under stress conditions
Greenhouse gases (GHGs) emission	Low, and global warming potential is also less	Higher GHGs emission and global warming potential	Very low GHGs emission and global warming potential
Use of machinery	Controlled traffic, no compaction in crop area, compaction in tramline	Free-wheeling of farm machinery, increased soil compaction	No compaction in crop area
Diesel use and costs	Diesel use much reduced	Diesel use high	Lowest use of diesel
Production costs	Low	High	Very low
Yield	Yields on a par with CT, but can surpass if planting is performed in advance	Generally lower than CA and delayed planting further reduces productivity	Productivity of grains is higher, due to advanced planting

) between various crop establishment methods i.e., conventional tillage (CT), conservation agriculture (CA), and SS, reveals that zero tillage (ZT) practices with residue (R) retention have a convenient resemblance to SS. Therefore, we comprehensively searched the peer-reviewed publications investigating the effects of ZT with R retention in relation to the CT practices on soil physico–chemical properties, using the Web of Science (Elsevier) indexing service, Google Scholar, and other academic websites. Conference proceedings and non-English language publications were excluded. Studies were selected exclusively based on the following criteria:

• Only picking up the experiments conducted in the IGP with RWCS;
• Mostly considered the experimental findings reported in 2016 and onwards in peer-reviewed publications/journals. Some experiments with good fundamental knowledge are also included that are published before 2016;
• Only field experiments were selected with side-by-side comparisons of ZT and CT practices;
• Experiments conducted for at least 2 years were considered;
• If R applied, CT taken as CT without R (CT − R), and ZT taken as ZT with R (ZT + R);
• If other factors such as irrigation, fertilizer application rate, varieties, etc. are implemented in a combination with tillage practices, then common irrigation, fertilizer application rate, varieties, etc. (package and practices) were selected during the comparison between CT and ZT;
• The only difference in the herbicidal application was considered during the comparison between CT and ZT;
• In case the mean value is not available, for comparison between CT and ZT, the most significant one throughout the years of the experiment was selected. Otherwise, the mean value was considered for comparison between CT and ZT;
• For soil properties, only upper soil layer differences were considered among CT and ZT.

In a nutshell, we can say that under CA, the sowing of wheat is performed through a Turbo Happy Seeder or zero-tillage machines; however, in SS, wheat seeds are broadcast manually. Therefore, SS causes minimal harm to the environment by way of GHGs emission in comparison to CA.

3. Crop Productivity in Surface Seeding

The late planting of wheat strings along with rice–wheat systems. Except for Punjab, 25–35% of the wheat area in the Indian IGP is estimated to be sown late, which markedly dwindles wheat productivity. Terminal heat entails a decrease in wheat yield potential by 1–1.5% per day if planting ensues after 15 November [9]. The delay in the planting of the wheat crop is a consequence of late rice harvesting, which corresponds to both the late establishment of rice, and the long duration of this crop. As a matter of fact, farmers grow fine-quality basmati rice in some parts of the IGP, which requires a longer duration to reach maturity. However, in the eastern IGP, long-duration and short-grain rice varieties are preferred, due to water lodging resulting in late wheat sowing. Other reasons for the late sowing of wheat in this region are long turnaround periods, which often imply intensive tillage operations, inadequate draft and mechanical power for ploughing, soil moisture problems (soil either too wet or too dry), and the urgency to store the harvested rice before preparing the land for wheat cultivation. Surface seeding promotes timely wheat establishment, as sowing wheat crop in a standing rice field greatly minimizes the turnaround time.

A brief review comparing the work conducted on the effects of SS implementation on wheat productivity is presented in

Table 2. Effect of surface seeding on wheat yield in different regions of India.

Location	Soil Type	Variety	Grain Yield (t ha−1)	Increase over Conventional Practices (%)	References
Bihar	SC	-	5.2	11	[26]
	SC	HD 2967	5.5	18	[17]
	SL	-	5.2	22	[18]
	-	-	2.7	4.5	[31]
Haryana	Loam	DBW 17	6.2	25	[32]
	CL	DPW 621-50	6.2	7.4	[33]
	Silt loam	HD 2967	6.0	13	[34]
	Loam	-	5.5	7.0	[16]
	Loam	-	5.4	7.4	[35]
	-	DPW 621–50	6.4	17	[12]
Madhya Pradesh	CL	MP 4010	4.7	5.8	[36]
New Delhi	Loam	HD 2894	4.9	8.6	[37]
	SL	HD 2967	4.7	15	[19]
	SL	HD 2967	5.0	8.0	[38]
Punjab	SL	HD 2967	5.7	6.8	[39]
	SL	HD 2967	5.2	7.4	[40]
	SL	HD 2967	5.8	8.7	[21]
Uttar Pradesh	SL	-	6.0	20	[41]
	SL	PBW 343	5.4	13	[42]
	SL	Pusa 1121	4.8	18	[43]
	SCL	HUW 234	3.6	5.8	[44]
Uttarakhand	-	UP 2565	3.6	−8.9	[15]
	CL	UP 2628	4.7	2.2	[45]
	SL	PBW 343	4.6	3.2	[46]
	SCL	Wheat 804	3.6	0.3	[13]
West Bengal	SL, CL to clay	-	3.1	15	[47]
	SCL	K 0307	3.4	6.3	[48]
	SL	-	4.0	10	[49]
Eastern Gangetic Plains, south Asia	Loam to SL	-	3.3	5.1	[50]

Note: SCL: sandy clay loam; SL: sandy loam; CL: clay loam; SC: silt clay.

. Contrasting results are demonstrated regarding wheat productivity, varying froma0.3 to 25% increase [15,16,17,18]. Generally, increased crop yields under SS are attributed to the improved soil properties, including water infiltration rate, higher SOC, soil aggregation, moisture- and nutrient-availability, and microbial activity [12,16,19,20,21,22,23]. However, it is also reported [24] that positive effects of SS on wheat yield under RW systems are predominantly the outcome of: (a) timely sowing, (b) increased input use efficiency, and (c) weed control. Adopting SS helps to increase long-term farm profitability, as it reduces the number of operations and fuel cost. One of the prime merits of SS, which popularizes it among the farming community, is that it reduces input cost and ensures timely sowing, resulting in higher wheat yields.

A number of studies emphasize the adoption of ZT with crop R retention in IGP for the perpetuation of crop yields and system productivity [25,26,27]. Correspondingly, Bangladeshi farms using SS practices register higher yields, with more profitability [28]. In fact, yield levels of the ZT with crop R retention are proportionate to CT in a long-term experiment conducted in central India, although the energy and labor savings are much greater under the former [29]. The gradual adoption of SS practices for wheat sowing in the RWCS has a direct yield advantage in the eastern IGP, and with the improvement in soil quality, the other beneficial effects are expected to eventually burgeon [30].

4. Resource Use Efficiency in Surface Seeding

Water scarcity is becoming a binding constraint to real agriculture in the IGP; fulfilling the domestic and industrial requirements is similar to walking a tightrope in the current poor water-use efficiency scenario [9]. Over-exploitation of below ground aquifers, when combined with poor water management, exacerbates the predicament of water logging and salinity in some areas, and declining water tables in others [8,51]. Depletion of groundwater resources at an alarming rate is major topic of concern. Management practices based on SS utilize residual moisture, reduce pre-sowing irrigation, and present an immense capability to resolve the issue, as it enhances water-use efficiency (

Table 3. Effects of surface seeding on nutrients management and water-use efficiency of wheat grown in different regions of India.

Location	Soil Type	Nutrients Application Rate (kg ha−1)	Total Water Productivity (kg Grain m−3 Water)	Increase over Conventional Practices (%)	Reference
Bihar	SL	N:150, P2O5:60, K2O:40	-	-	[18]
Haryana	Loam	-	1.3	13	[32]
	Silt loam	N:135, P2O5:62, K2O:60	1.4	30	[34]
	-	N:150, P2O5:26, K2O:50	0.9	67	[12]
New Delhi	SL	N:150, P2O5:80, K2O:60	-	-	[38]
Punjab	SL	N:120, P2O5:25, K2O:25	-	-	[39]
Uttar Pradesh	SL	N:120, P2O5:26, K2O:50	1.4	44	[41]
	SL	N:150, P2O5:26, K2O:50	-	-	[42]
	SL	N:150, P2O5:26, K2O:50	-	-	[43]
West Bengal	SL	N:150, P2O5:26.3, K2O:33.3	-	-	[49]
Haryana	CL	N:150, P2O5:60, K2O:60	Water consumption: 0.5	36	[33]
Madhya Pradesh	CL	N:120, P2O5:26.2, K2O:33.1	WUE: 131 kg grain ha−1 cm−1	14	[36]
Uttarakhand	-	N:120, P2O5:60, K2O:40	WUE: 16 kg ha−1 mm−1	13 decreases	[15]
Uttarakhand	SCL	N:100, P2O5:60, K2O:40	WUE: 11 kg ha−1 mm−1	2.8	[13]
Eastern Gangetic Plains, south Asia	Loam to SL	N:60–145, P2O5:11–45, K2O:14 to 50	2.5	30	[50]

Note: SCL: sandy clay loam; SL: sandy loam; CL: clay loam; WUE: water-use efficiency.

). This could prove to be advantageous for the IGP, where farmlands are facing acute water shortages, and the lowering of the water table in some of the RW areas as a repercussion of extreme groundwater pumping [12,18,33]. Progress in crop water productivity (CWP) holds the promise of food security, as well as water sustainability in RW cropping systems of the IGP [13,34,50,52]. Crop establishment technologies, with an emphasis on resource conservation, are normally reported to preserve 20–35% of irrigation water in the wheat against conventional practices [9]. A zero-tillage-based rice–wheat–maize system (RWMS) shows enhanced water productivity over a conventional RW system [20]. The irrigation WP under the RW system demonstrates an augmentation of145% under SS compared to farmers’ practice [53]. Moreover, SS can improve soil structure and facilitate buildup of crop debris, which directly correlates with an increase in water retention and better infiltration, along with a decrease in overall water use elsewhere [24]. Additionally, the faster turnaround time effectuated by SS allows for the early planting and harvesting of wheat crops, which, in some regions, potentially eliminates the need for one or more late-season irrigations. The availability of nutrients to the plant is substantially influenced by water availability. Plants absorb nutrients predominantly through transportation and diffusion processes that are governed by water. As a result, high WUE not only saves water, but also improves nutrient availability to plants.

Irrigation boosts agricultural productivity by expanding cultivable land far more than is possible with rain-fed agriculture, and increasing crop yields. Irrigation boosts yields not just by reducing or preventing crop water stress, but also by reaping the additional benefits of combining irrigation with high-yielding cultivars, fertilizer, and herbicides. In developing nations, irrigation is a critical component of agricultural productivity. In the years 1997–1999, irrigated land supplied two-fifths of agricultural yields in developing nations, accounting for around one-fifth of cultivated areas. Irrigated cereal yields out-performed rain-fed yields by 115% in developing nations [54]. Increased food production from irrigated agriculture can provide nutritional benefits to farmers, their families, and the local community. Irrigation allows for multiple cropping, which can help to relieve seasonal food supply gaps, and stimulate the development of crops that contribute to a more diversified and healthy diet. Improved nutrition can improve quality of life, reduce disease, raise labor productivity, and boost children’s academic achievement [55]. Sun et al. [56] report that increased irrigation significantly increases the bulk density (BD) of soil by 5% to 8% in the upper 20 cm, and decreases salt concentrations [57]. Irrigation enhances the nutrients availability to the crop. However, the irrigable water resources are depleted continuously, as a result of environmental pollution and over-exploitation of groundwater resources. Hence, rural communities are eager to adopt such technologies that enhance water productivity and water-use efficiency. However, the adoption of micro-sprinkler and drip irrigation is not so popular among farmers, due to its high cost and maintenance.

5. Weed Management under Surface Seeding

In SS, weed problems are identified as a major issue for management [33,50]. In conventional approaches, tillage operations are performed mainly for weed control, firming seedbeds, and uniform germination [58]. However, the matter of weed control under SS is largely dealt with using herbicides (

Table 4. Various weed management practices under surface seeding adopted in different regions of India.

Location	Soil Type	Weed Management Practices	References
Bihar	SL	Glyphosate @ 1.0 kg a.i. ha−1 is used as pre-plant 2 days before sowing, to kill existing weeds. Pre-mix herbicide sulfosulfuron + metsulfuron @ 32 g a.i. ha−1 at 30–35 DAS.	[18]
Haryana	Loam	In the 1st year, pre-mixed herbicide sulfosulfuron + metsulfuron @ 32 g a.i. ha−1 is applied at 35 DAS. In 2nd year, tank mixture of clodinafop-ethyl + metsulfuron @ 60 + 4 g a.i. ha−1 is applied at 35 DAS.	[32]
Haryana	CL	Glyphosate @ 1.25 kg a.i. ha−1 sprayed pre-planting of wheat. Total (metsulfuron methyl 75% + sulfosulfuron) @ 1250 mL a.i. ha−1 is sprayed to control weeds after emergence.	[33]
New Delhi	SL	Pendimethalin 1.0 kg ha−1 applied before emergence (1 DAS), followed by sulfosulfuron @ 25 g ha−1 after emergence (25 DAS).	[38]
Uttar Pradesh	SL	Glyphosate @ 900 g a.i. ha−1 sprayed before the sowing of wheat.	[41]
	SL	Glyphosate at 900 g a.i. ha−1 sprayed as pre-plant of wheat. Grassy and broad-leaf weeds are managed by spraying sulfosulfuron + metsulfuron methyl @ 35 g a.i. + 4 g a.i. ha–1 at 25–30 DAS.	[65]
West Bengal	SL	Glyphosate 41% S.L. at 3.75 l ha−1 applied 7 days prior to sowing, to smother the existing weed flora. 2,4-D Na salt 80% W.P. at 1 kg a.i. ha−1 at 4–5 weeks after sowing, to smother the broad-leaf weed flora.	[49]
Eastern Gangetic Plains, south Asia	Loam to SL	Glyphosate sprayed 4 to 7 days before the sowing of wheat	[50]
Uttarakhand	SL	Dominant grassy weeds flora is Phalaris minor (55.0%), whereas major non-grassy weed is Melilotus indica in wheat crop.	[66]

Note: SL: sandy loam; CL: clay loam.

). Glyphosate [N-(phosphor no methyl) glycine], a broad-spectrum herbicide, is mainly used in the absence of extensive tillage to manage weed infestation [38,44,49]. In addition to glyphosate, other herbicides, such as 2,4-D (2,4–dichlorophenoxy acetic acid), clodinafop-ethyl, metsulfuron, sulfosulfuron, etc., are applied to control the weeds [18,32]. Indisputably, countries that previously used relatively higher amounts of herbicides are already experiencing retribution, in the form of environmental hazards and the emergence of herbicide-resistant weeds [59]. Therefore, under the SS system, it is duly advised to use the optimum dose of an appropriate herbicides, at the right time, for an efficient weed control [60]. Likewise, repeated herbicide usage under SS sometimes leads to weed shift, a herbicide-resistant weed population [61], and the dominance of a certain weed species as opposed to in conventional farming practices [62]. In an attempt to manage this problem efficiently, devising an integrated weed management approach, including the selection of appropriate cropping systems and cultivars with SS principles’ reinforcement, would be worthwhile [63,64]. In the eastern IGP, SS is mostly practiced in the standing rice crop, and farmers harvest the rice crop generally 7–10 days after sowing. During harvesting, germinated seeds are covered by the rice straw for 4–5 days until it properly dries, and is then collected manually. Thus, the 10 days of straw coverage reduce the germination of many winter weeds. Use of broad-spectrum weedicides, i.e., glyphosate, is not possible in this practice. The reduction in the weed population is observed in SS under puddled rice.

6. Soil Health under Surface Seeding

6.1. Physical Properties

Tillage is usually considered by farmers as a practice in which soil is physically manipulated for the better crop establishment. Keeping this in perspective, the modifications in the soil’s physical properties deliberately affect the soil and ecosystem [67,68]; moreover, extensive tillage operations may eventually ravage the soil health. Farming communities in the IGP zones also practice excessive tillage, which significantly deteriorates the physical properties of soil, such as bulk density (BD), water-holding capacity (WHC), aggregate stability, porosity, etc. [69]. Apropos to this, Alakukku et al. [70] describe the consequent formation of subsurface hardpan after continuous ploughing at the same depth, resulting in reduced nutrient and WUE, as well as root growth. On the flip side, SS aids in inhibiting the deterioration in soil quality due to CT practices, through the revival of soil’s physio–chemo–biological properties (

Table 5. Effects of surface seeding on soil physical properties in wheat grown in different regions of India.

Location	Soil Type	Effect on Soil Properties	Change over Conventional Practices (%)	Reference
Bihar	Entisol	Bulk density: 1.5 Mg m3	−6.5	[33]
	-	Bulk density: 1.5 g cm3	−6.4	[20]
Haryana	Loam	Bulk density: 1.6 Mg m3	−2.4	[16]
Madhya Pradesh	CL	Bulk density: 1.5 Mg m3	−3.9	[18]
New Delhi	SL	Bulk density: 1.5 Mg m3	−1.3	[76]
Punjab	SL	Bulk density: 1.6 Mg m3	6.7	[23]
Uttar Pradesh	SL	Bulk density: 1.6 Mg m3	4.7	[42]
Uttarakhand	-	Bulk density: 1.4 Mg m3	2.9	[15]
	SCL	Bulk density: 1.3 Mg m3	2.3	[13]
New Delhi	SL	Mean weight–diameter: 0.4 mm	13	[38]
Punjab	SL	Mean weight–diameter: 1.2 mm	10	[23]
Uttar Pradesh	SL	Mean weight–diameter: 2.7 mm	102	[41]
	SL	Mean weight–diameter: 1.2 mm	32	[44]
Uttarakhand	-	Mean weight–diameter: 0.7 mm	4.2	[15]
	SL	Soil aggregates (>0.25 mm): 70%	35	[41]
	SL	Soil aggregates (>0.25 mm): 75%	51	[42]
Bihar	-	Water-stable soil aggregates (MWD): 6.1 mm	407	[20]
Haryana	Loam	Aggregate stability: 46%	91	[53]
	Loam	Water-stable macro-aggregates: micro-aggregates: 7.9	796	[53]
Uttar Pradesh	SL	Aggregate ratio: 4.3	83	[44]
Bihar	-	Air-filled porosity: 45.1%	9.1	[20]
Uttarakhand	SCL	Total porosity: 53%	2.3	[13]
	-	Effective porosity: 1.9 m3 m−3	7.5	[15]
Bihar	-	Water-holding capacity: 55%	40	[20]
Haryana	Loam	Infiltration rate: 0.3 cm hr−1	244	[16]
Madhya Pradesh	CL	Infiltration rate: 5.8 mm hr−1	18	[36]
Punjab	SL	Steady-state infiltration: 1.0 cm h−1	25	[23]
Uttar Pradesh	SL	Steady-state infiltration: 0.4 cm h−1	200	[42]
	SL	Steady-state infiltration: >0.1 cm hr−1	67	[43]
Uttarakhand	-	Saturated hydraulic conductivity: 21	−2.3	[15]
Haryana	Loam	Volumetric water content: 27%	50	[16]

Note: SCL: sandy clay loam; SL: sandy loam; CL: clay loam.

, Table 6 and Table 7). A brief account of the work performed by researchers in the IGP under the RW system (Table 5) clearly demonstrates a reduction in soil bulk density, and increases in mean weight–diameter (MWD), aggregate stability, and infiltration rate in loam to sandy loam soils under SS over CT. Intensive tillage, non-recycling of crop residue to soil systems, and mono-culture systems-mediated degradation of soil structure and aggregation contribute to a decline in the rate of infiltration under intensively irrigated rice–wheat agro-ecosystems. It inversely affects soil hydraulic conductivity and groundwater recharge, resulting in a consequent depletion of groundwater in such instances [13,20,65,71,72]. When sandy loam soils are exposed to SS rather than CT, the infiltration rate is accelerated by ∼50%, owing to the formation of stable aggregates [12,16,73,74]. The higher infiltration rates in the SS-based RW cropping system facilitate speedy water percolation, and reduce the quantity of run-off that might end up as groundwater recharge [44,75].

The major crop growth benefits of SS manifest through reduced soil erosion, crusting, compaction, and moderated soil hydrothermal regimes [15,18,23,33]. This practice leads to a supportive soil physical environment, which not only promotes root growth and nutrient recycling, but also SOC sequestration [2,17,18,76]. Experimental evidence involving SS shows a substantial decrease in BD and penetration resistance (PR) [34], with a significant increase in soil moisture content, water-stable aggregates (WSA) (>0.25 mm), and MWD, mainly in the topsoil (0–15 cm) layer [2]. Furthermore, soil type and climatic conditions implicitly control the quantum of the impact of SS on the soil’s physical properties. Under the semi-arid conditions, sandy loam soil exhibits a higher WSA (16.1–32.5%), with a significantly decreased PR and BD [27]. Singh et al. [77] document similar results in their five year-long study on sandy loam soil; in accordance with which, Somasundaram et al. [2] observe an increase in WSA (10%) and MWD (20%) in clay soil under the hot sub-humid condition compared to CT four years post-experimentation; meanwhile no significant pattern is observed relative to BD in clayey soil during that time period. Multiple reports advocate the combined implementation of R with a ZT system to yield greater benefits concerning soil’s physical properties [2]; contradictorily, Meena et al. [78] report a 12% and 33% higher MWD for ZT + R and NT − R than CT + R and CT − R, respectively, which implies that the effect of ploughing is more prominent over the addition of R.

6.2. Chemical Properties

The effects of SS practices on the chemical properties of soil are briefly summarized in Table 6. Evidently, favorable impacts are noticed with the ZT operations, i.e., retention and recycling of crop residues on the soil surface in SS [12,18]; the pH is reduced, and the content of available N, P, K, and micronutrients increases in soil over CT. Additionally, the stratification of nutrients and their accumulation near the root zone are detected under SS [16,39,40,49]. Several researchers gathered evidence regarding increased SOC and total nitrogen (N) stocks with the adoption of SS practices involving ZT and crop residue retention, along with optimum nutrient application [39,75,76]. By increasing the quantity of C, soil C sequestration is enhanced, and/or the rate of soil C loss reduced, which primarily depends on the local soil and climate conditions [79]. Yadav et al. [66], in their work encompassing the north–eastern region of India, report that by employing SS practices, such as ZT + integrated plant nutrient management (IPNM) + 30% R incorporation in RWCS, higher SOC sequestration (427.9 kg ha⁻¹ yr⁻¹) is achieved. The soil nutrient availability is evaluated by Jat et al. [16] under the SS practices in north–west India, where the highest SOC (7.7 g kg⁻¹) is found under SS, compared to that under CT (4.5 g kg⁻¹). At the depth of 0–15 cm, the available N is higher in SS-based RWMS (33%) and SS-based maize–wheat–mungbean (MWM; 68%) than a conventionally grown RW cropping system. With respect to available P, a 25% and 38% higher concentration is detected under SS-based MWM and SS-based RWMS, respectively, relative to the conventional system. A plausible explanation for this could be the higher R retention and moderation of the soil moisture and temperature by water absorption, where R acts as an insulating material to resist the change in heat, which is conducive for growth at or near the soil surface. As crop debris contains high concentrations of total K, it could contribute to a higher available K level in soil [18,40]. Apart from these, in other research work conducted in the north–western IGP, the adoption of ZT proves to be beneficial in terms of SOC accumulation and N uptake [80]. In central India, Hati et al. [81] and Kushwa et al. [82] witness that ZT soils display more SOC and P concentration in the surface layers than at depth, in contrast to those exposed to CT under a soybean–wheat system. Similarly, a comparative study conducted by Mohammad et al. [75] in Pakistan shows a higher SOM, and mineralizable C and N, along with total N, P, K, in a minimum tillage (MT) experiment, as compared to that of CT and deep tillage at 0–30 cm soil depths.

Table 6. Effects of surface seeding on soil chemical properties in wheat grown in different regions of India.

Location	Soil Type	Effect on Soil Properties	Change over Conventional Practices (%)	Reference
Haryana	Loam	pH: 7.6	−3.5	[35]
	Loam	pH: 7.8	−2.7	[16]
	Loam	Available N: 156 kg ha−1	33	[16]
	-	Available N: 216 kg ha−1	39	[12]
Madhya Pradesh	CL	Available N: 221 kg ha−1	7.3	[36]
Punjab	SL	Available N: 60 mg kg−1	54	[39]
West Bengal	SL	Mineralizable N: 149 kg ha−1	9.6	[49]
Haryana	Loam	Total N: 0.2%	36	[16]
	Loam	Available P: 21.5 kg ha−1	38	[16]
	-	Available P: 23 kg ha−1	41	[12]
Madhya Pradesh	CL	Available P: 9.9 kg ha−1	19	[36]
Punjab	SL	Available P: 11 mg kg−1	14	[39]
	SL	Available P: 21 mg kg−1	9.2	[40]
West Bengal	SL	Available P: 42 kg ha−1	7.8	[49]
Haryana	Loam	Available K: 236 kg ha−1	29	[16]
	-	Available K: 312 kg ha−1	40	[12]
Madhya Pradesh	CL	Available K: 197 kg ha−1	7.7	[36]
Punjab	SL	Available K: 74 mg kg−1	3.6	[40]
West Bengal	SL	Available K: 226 kg ha−1	3.2	[49]
Haryana	Loam	Available S: 19 mg kg−1	−8.2	[16]
	Loam	DTPA-extractable Zn: 9.2 mg kg−1	93	[16]
	Loam	DTPA-extractable Fe: 136 mg kg−1	3.0	[16]
	Loam	DTPA-extractable Mn: 99 mg kg−1	21	[16]

Note: SL: sandy loam; CL: clay loam.

Table 6. Effects of surface seeding on soil chemical properties in wheat grown in different regions of India.

Location	Soil Type	Effect on Soil Properties	Change over Conventional Practices (%)	Reference
Haryana	Loam	pH: 7.6	−3.5	[35]
	Loam	pH: 7.8	−2.7	[16]
	Loam	Available N: 156 kg ha−1	33	[16]
	-	Available N: 216 kg ha−1	39	[12]
Madhya Pradesh	CL	Available N: 221 kg ha−1	7.3	[36]
Punjab	SL	Available N: 60 mg kg−1	54	[39]
West Bengal	SL	Mineralizable N: 149 kg ha−1	9.6	[49]
Haryana	Loam	Total N: 0.2%	36	[16]
	Loam	Available P: 21.5 kg ha−1	38	[16]
	-	Available P: 23 kg ha−1	41	[12]
Madhya Pradesh	CL	Available P: 9.9 kg ha−1	19	[36]
Punjab	SL	Available P: 11 mg kg−1	14	[39]
	SL	Available P: 21 mg kg−1	9.2	[40]
West Bengal	SL	Available P: 42 kg ha−1	7.8	[49]
Haryana	Loam	Available K: 236 kg ha−1	29	[16]
	-	Available K: 312 kg ha−1	40	[12]
Madhya Pradesh	CL	Available K: 197 kg ha−1	7.7	[36]
Punjab	SL	Available K: 74 mg kg−1	3.6	[40]
West Bengal	SL	Available K: 226 kg ha−1	3.2	[49]
Haryana	Loam	Available S: 19 mg kg−1	−8.2	[16]
	Loam	DTPA-extractable Zn: 9.2 mg kg−1	93	[16]
	Loam	DTPA-extractable Fe: 136 mg kg−1	3.0	[16]
	Loam	DTPA-extractable Mn: 99 mg kg−1	21	[16]

Note: SL: sandy loam; CL: clay loam.

6.3. Biological Properties

The ZT in combination with R effectively diminishes the oxidation rate of SOC and crop residue, which improves the SOC content. The effect of SS on soil biological properties (Table 7) reveals a significant increase compared to CT with respect to microbial biomass carbon (MBC), and the activity of soil enzymes such as dehydrogenase, alkaline phosphatase, urease, and phytase. The higher SOC leads to higher MBC, and microbial and mineralization quotients that are the biological indicators under the SS-based system. A significantly higher correlation is witnessed by Bera et al. [39], in relation to SOC: MBC (0.93), SOC: BSR (basal soil respiration) (0.84), and SOC: Qm (carbon mineralization quotient) (0.70) in an RW system while employing various tillage management practices in India. Significant improvements in MBC, basal soil respiration, and microbial and mineralization quotients are observed in the ZT plot as opposed to CT [83]. This is presumably due to the limited microbial decomposition of SOC under ZT which, in contrast to CT, results in greater stabilization of micro-and macro-aggregates, and provides a physical barrier between organic matter and decomposers [84]. Surface seeding also provides a suitable environment for microbial proliferation, due to the retention of crop residue compared to the removal of residue or burning [85]. Diverse microbial communities regulate specific functions associated with the decomposition of crop residues. The soil bacteria instigate the process, while later phases of crop residue decomposition is dominated by fungi [86,87]. The agricultural management practices also influence the soil microbial community structure [88]. Indeed, a study conducted in central Mexico documents that ZT practice coupled with crop R retention augments fungal abundance, and significantly affects the bacterial community structure, thereby promoting the abundance of Bacteroidetes, Betaproteobacteria, and Gemmatimonadetes [89]. These microorganisms take part in several biogeochemical processes, such as C and N cycles, alongside their function of being a storehouse of plant nutrients [90]. Intensive tillage negatively impacts the distribution and abundance of soil microbes, by influencing soil moisture and thermal regimes, as well as nutrient dynamics [91]. Moreover, this practice destroys soil structure, which portends alteration in the abundance and diversity of microbes when compared to the SS system [35,92].

The previous literature suggests that a reduction in tillage accompanies enhanced chemical and microbial activity, microbial biomass, and enzymatic actives such as dehydrogenase, alkaline phosphatase, etc. [19,35,44,93] (Table 7). Parihar et al. [94] report an increase in soil MBC by 45–48.9% under SS-based systems in sandy loam (Typic Haplustept) soil profiles (0–30 cm deep) in the north–western IGP. Concurrently, an SS-based maize–wheat cropping system (MWCS) improves soil MBC (208%), MBN (263%), and dehydrogenase (210%), and alkaline phosphatase activity (48%), when compared with the conventional practice of the RW system [35]. However, the SS-based RW system enhances the soil MBC and MBN up to 40%, as well as the dehydrogenase and alkaline phosphatase activity by up to 15% [12,53]. In cereal systems predicated on SS, a higher micro-arthropod population is witnessed under RW compared to the MW system. Also, an SS-based MW system secures the uppermost soil quality index (SQI) score of 1.45, while with a CA-based RW system, it is 0.58, with the lowermost score of 0.29 comes from the conventional RW system [35].

Table 7. Effects of surface seeding on soil biological properties in wheat grown in different regions of India.

Location	Soil Type	Effect on Soil Properties	Change over Conventional Practices (%)	Reference
Haryana	Loam	MBC: 207 μg g−1 dry soil	22	[35]
	-	MBC: 1113 μg g−1 dry soil	122	[16]
	SL	MBC: 257 μg g−1 soil	29	[88]
New Delhi	SL	MBC: 145 mg kg−1 soil	27	[19]
	SL	MBC: 65 mg kg−1 soil	-	[95]
	SL	MBC: 140 μg g−1 soil	20	[38]
Punjab	SL	MBC: 333 μg g−1 soil	57	[23]
	SL	MBC: 138 μgCmic g−1 soil	39	[83]
Uttar Pradesh	SL	MBC: 164 mg kg−1 dry soil	47	[44]
Uttarakhand	SCL	MBC: 0.3 g kg−1	23	[13]
Haryana	Loam	MBN: 80 μg g−1 dry soil	36	[35]
	-	MBN: 433 μg g−1 dry soil	171	[16]
	SL	MBN: 61 μg g−1 soil	56	[88]
	SL	Bacterial PLFA: 82 nmol g−1	52	[88]
	SL	Fungal PLFA: 7.3 nmol g−1	135	[88]
West Bengal	Entisol	Actinomycetes population: 95 × 105 CFU g−1	17	[93]
Haryana	Loam	Dehydrogenase: 51 µg TPF g−1 24h−1	37	[35]
New Delhi	SL	Dehydrogenase: 247 µg TPF g−1 24 h−1	-	[95]
Punjab	SL	Dehydrogenase: 18 µg TPF g−1 h−1	21	[39]
	SL	Dehydrogenase: 14 µg TPF g−1 h−1	39	[21]
New Delhi	SL	Fluorescein di-acetate: 18 μg fluorescein g−1 hr−1	-	[95]
Punjab	SL	Fluorescein di-acetate: 1.3 μg fluorescein g−1 dry soil	13	[39]
	SL	Fluorescein di-acetate: 1.1 μg fluorescein g−1 h−1	19	[21]
Haryana	Loam	Alkaline phosphatase activity: 52 µg p-nitrophenol g–1 h–1	53	[35]
Punjab	SL	Alkaline phosphatase activity: 86 µg p-nitrophenol g–1 h–1	48	[39]
	SL	Alkaline phosphatase activity: 53 µg p-nitrophenol g–1 h–1	29	[21]
New Delhi	SL	Acid phosphatase: 127 μmol p-nitrophenol g−1 h−1	-	[95]
Punjab	SL	Acid phosphatase activity: 33 µg p-nitrophenol g–1 h–1	5.9	[39]
	SL	Acid phosphatase activity: 25 µg p-nitrophenol g–1 h–1	37	[21]
Haryana	Loam	β-glycosidase activity: 43 µg p-nitrophenol g–1 h–1	19	[35]
Punjab	SL	β-glycosidase activity: 36 µg p-nitrophenol g–1 h–1	96	[39]
Punjab	SL	β-glucosidase activity: 16 μg PNP g−1 hr−1	25	[21]
	SL	Urease activity: 4.6 µg urea g–1 min–1	1.1	[39]
	SL	Urease activity: 3.9 µg urea g–1 min–1	1.3	[21]
	SL	Phytase activity: 0.7 µg g–1 h–1	24	[21]
	SL	Phytase activity: 0.5 µg g–1 h–1	35	[21]
	SL	Asparaginase activity: 39 μg g−1 hr−1	43	[21]
	SL	Xylanase activity: 33 μg glucose g−1 hr−1	34	[21]
	SL	Cellulase activity: 16 μg glucose g−1 hr−1	71	[21]
	SL	Phenol oxidase activity: 0.4 μg DOPA g−1 hr−1	−38	[21]
	SL	Peroxidase activity: 5.5 μg DOPA g−1 hr−1	−23	[21]
	SL	Metabolic quotient: 1.2 μg C-CO2 cumulative μg total organic carbon−1	16	[21]
New Delhi	SL	Fluorescein di-acetate, urease, and total phosphatase activities	13, 13l and 25%, respectively	[38]
Punjab	SL	Dehydrogenase, urease, acid, and alkaline phosphatase activity	13, 5, 25l and 16, respectively	[23]

Note: SL: sandy loam; CL: clay loam; SCL: sandy clay loam; MBC: microbial biomass carbon; MBN: microbial biomass nitrogen.

Table 7. Effects of surface seeding on soil biological properties in wheat grown in different regions of India.

Location	Soil Type	Effect on Soil Properties	Change over Conventional Practices (%)	Reference
Haryana	Loam	MBC: 207 μg g−1 dry soil	22	[35]
	-	MBC: 1113 μg g−1 dry soil	122	[16]
	SL	MBC: 257 μg g−1 soil	29	[88]
New Delhi	SL	MBC: 145 mg kg−1 soil	27	[19]
	SL	MBC: 65 mg kg−1 soil	-	[95]
	SL	MBC: 140 μg g−1 soil	20	[38]
Punjab	SL	MBC: 333 μg g−1 soil	57	[23]
	SL	MBC: 138 μgCmic g−1 soil	39	[83]
Uttar Pradesh	SL	MBC: 164 mg kg−1 dry soil	47	[44]
Uttarakhand	SCL	MBC: 0.3 g kg−1	23	[13]
Haryana	Loam	MBN: 80 μg g−1 dry soil	36	[35]
	-	MBN: 433 μg g−1 dry soil	171	[16]
	SL	MBN: 61 μg g−1 soil	56	[88]
	SL	Bacterial PLFA: 82 nmol g−1	52	[88]
	SL	Fungal PLFA: 7.3 nmol g−1	135	[88]
West Bengal	Entisol	Actinomycetes population: 95 × 105 CFU g−1	17	[93]
Haryana	Loam	Dehydrogenase: 51 µg TPF g−1 24h−1	37	[35]
New Delhi	SL	Dehydrogenase: 247 µg TPF g−1 24 h−1	-	[95]
Punjab	SL	Dehydrogenase: 18 µg TPF g−1 h−1	21	[39]
	SL	Dehydrogenase: 14 µg TPF g−1 h−1	39	[21]
New Delhi	SL	Fluorescein di-acetate: 18 μg fluorescein g−1 hr−1	-	[95]
Punjab	SL	Fluorescein di-acetate: 1.3 μg fluorescein g−1 dry soil	13	[39]
	SL	Fluorescein di-acetate: 1.1 μg fluorescein g−1 h−1	19	[21]
Haryana	Loam	Alkaline phosphatase activity: 52 µg p-nitrophenol g–1 h–1	53	[35]
Punjab	SL	Alkaline phosphatase activity: 86 µg p-nitrophenol g–1 h–1	48	[39]
	SL	Alkaline phosphatase activity: 53 µg p-nitrophenol g–1 h–1	29	[21]
New Delhi	SL	Acid phosphatase: 127 μmol p-nitrophenol g−1 h−1	-	[95]
Punjab	SL	Acid phosphatase activity: 33 µg p-nitrophenol g–1 h–1	5.9	[39]
	SL	Acid phosphatase activity: 25 µg p-nitrophenol g–1 h–1	37	[21]
Haryana	Loam	β-glycosidase activity: 43 µg p-nitrophenol g–1 h–1	19	[35]
Punjab	SL	β-glycosidase activity: 36 µg p-nitrophenol g–1 h–1	96	[39]
Punjab	SL	β-glucosidase activity: 16 μg PNP g−1 hr−1	25	[21]
	SL	Urease activity: 4.6 µg urea g–1 min–1	1.1	[39]
	SL	Urease activity: 3.9 µg urea g–1 min–1	1.3	[21]
	SL	Phytase activity: 0.7 µg g–1 h–1	24	[21]
	SL	Phytase activity: 0.5 µg g–1 h–1	35	[21]
	SL	Asparaginase activity: 39 μg g−1 hr−1	43	[21]
	SL	Xylanase activity: 33 μg glucose g−1 hr−1	34	[21]
	SL	Cellulase activity: 16 μg glucose g−1 hr−1	71	[21]
	SL	Phenol oxidase activity: 0.4 μg DOPA g−1 hr−1	−38	[21]
	SL	Peroxidase activity: 5.5 μg DOPA g−1 hr−1	−23	[21]
	SL	Metabolic quotient: 1.2 μg C-CO2 cumulative μg total organic carbon−1	16	[21]
New Delhi	SL	Fluorescein di-acetate, urease, and total phosphatase activities	13, 13l and 25%, respectively	[38]
Punjab	SL	Dehydrogenase, urease, acid, and alkaline phosphatase activity	13, 5, 25l and 16, respectively	[23]

Note: SL: sandy loam; CL: clay loam; SCL: sandy clay loam; MBC: microbial biomass carbon; MBN: microbial biomass nitrogen.

7. Environmental Impact on Surface Seeding

Surface seeding is a climate-resilient resource-conserving technology (Figure 3). It has the potential to increase cost and yield with a minimal carbon footprint, as it tends to sequester organic carbon in soil (

Table 8. Effects of surface seeding on carbon footprint in wheat grown in different regions of India.

Location	Soil Type	Effects on Carbon Status or Accumulation	Increase over Conventional Practices (%)	References
Haryana	Loam	Organic carbon: 7.5 g kg−1	67	[16]
	Loam	Organic carbon: 6.1 g kg−1	30	[35]
	-	Organic carbon: 7.4 g kg−1	40	[12]
	Loam	Organic carbon: 8.1 g kg−1	65	[53]
Madhya Pradesh	CL	Organic carbon: 4.0 g kg−1	1.8	[18]
New Delhi	SCL	Organic carbon: 5.8 g kg−1	5.7	[98]
Punjab	SL	Organic carbon: 6.7 g kg−1	14	[39]
	SL	Organic carbon: 4.7 g kg−1	16	[40]
	SL	Organic carbon: 6.2 g kg−1	6.9	[23]
	SL	Organic carbon: 5.4 g kg−1	13	[83]
Uttar Pradesh	SL	Organic carbon: 5.2 g kg−1	40	[65]
Uttarakhand	-	Organic carbon: 7.6 g kg−1	2.7	[15]
	SCL	Organic carbon: 8.8 g kg−1	12	[13]
West Bengal	SL	Organic carbon: 9.8 g kg−1	10	[49]
Bihar	Entisol	Total soil organic carbon: 5.5 t ha−1	57	[33]
	Silt clay	Total soil organic carbon: 6.9 g kg−1	9.1	[17]
Haryana	Loam	Total soil organic carbon: 11 g kg−1	81	[53]
New Delhi	SCL	Total soil organic carbon: 7.3 g kg−1	4.3	[98]
	SL	Total soil organic carbon: 13 Mg ha−1	11	[19]
	SL	Total soil organic carbon: 5.1 g kg−1	-	[95]
	SL	Total soil organic carbon: 10 g kg−1	25	[76]
	SL	Total soil organic carbon: 7.6 Mg ha−1	23	[99]
	SCL	Total soil inorganic carbon: 2.1 g kg−1	−22	[98]
Bihar	Silt clay	Total soil organic carbon stock: 14 Mg ha−1	20	[26]
New Delhi	SL	Soil organic carbon stock: 13 Mg ha−1	9.7	[19]
Punjab	SL	Soil organic carbon stock: 14 Mg ha−1	16	[23]
New Delhi	SL	SOC sequestration: 3.5 Mg ha−1	2.6	[76]
	SL	SOC accumulation: 7.6 Mg ha−1	23	[76]
Punjab	Inceptisol	C-sequestration: 47.1 kg C ha−1	−9.9	[36]
Uttarakhand	SCL	C-sequestration: 25 Mg ha−1	8.6	[13]
	SCL	C-sequestration rate: 460 kg C ha−1 year−1	36	[13]
Bihar	Silt clay	Carbon management index: 111	11	[17]
New Delhi	SL	Carbon management index: 0.7	4.8	[76]
Uttar Pradesh	SL	Carbon management index: 154	41	[65]
New Delhi	SL	Oxidative stability of C: 0.5	20	[76]
Punjab	Inceptisol	Carbon sustainability index: 10	400	[36]

Note: SL: sandy loam; CL: clay loam; SCL: sandy clay loam.

), with lesser expenditure of energy and irrigation water, thus, reducing the total global warming potential (GWP) (

Table 9. Impact of adverse environment on surface seeding wheat grown in different regions of India.

Location	Soil Type	Environmental Stress	Change over Conventional Practices (%)	Reference
Haryana	SL to CL	N2O–N flux: 0.5 kg ha−1	14	[100]
	CL	N2O–N flux: 1.7 kg N ha−1	−32	[33]
	CL	N2O–N flux: 4.5 kg N ha−1	72	[33]
New Delhi	Loam	N2O–N flux: 0.9 kg ha−1	−2.2	[37]
	SL	N2O–N flux: 390 g ha−1	2.6	[19]
West Bengal	Entisol	N2O flux: 11 mg m−2 h−1	3.6	[93]
New Delhi	SL	CO2–C flux: 266 g ha−1	−17	[19]
Haryana	CL	GWP from emission: 825 kg CO2 eq ha−1	−31	[33]
	CL	GWP from emission: 2204 kg CO2 eq ha−1	72	[33]
	Silt loam	GWP: 4592 kg CO2 eq ha−1 yr−1	40	[34]
New Delhi	Loam	GWP: 378 kg CO2 eq ha−1	−4.8	[37]
	SL	GWP: 477 kg CO2 eq ha−1	−18	[19]
	Loam	GHG intensity: 0.1	−8.1	[37]
Punjab	Inceptisol	Total carbon equivalent emission: 1624 kg CO2 eq ha−1	−21	[36]
	Inceptisol	GWP: 2.1 Mg CO2 eq ha−1	−16	[36]
Haryana	Silt loam	GHG intensity: 0.4 kg kg−1 CO2 eq ha−1 yr−1	44	[34]
Punjab	Inceptisol	GHG intensity: 0.3 kg CO2 eq kg−1	−12	[36]
	Inceptisol	Carbon equivalent emission: 0.6 Mg CO2 eq ha−1	−17	[36]
Eastern Gangetic Plains, south Asia	-	Carbon dioxide equivalent emission: 1.4 Mg ha−1	−8.4	[14]

). With respect to the comparative GHGs emissions from SS and CT practices, Sapkota et al. [33] detect a 32% reduction in N₂O emissions in ZT and direct seeding. Similarly, Gupta et al. [37] estimate a minute decrease in N₂O emissions (2.2%) under ZT, which equates to a similar extent of reduction in the GWP. However, Kumar et al. [20] evaluate four wheat management strategies, and report that in an attempt to reduce the GWP of wheat, a soil matric potential (SMP) criteria must be used in place of applying irrigation water at certain intervals at critical crop growth stages. Irrespective of CO₂ emission, Nath et al. [19] observe a 17% decline in CO₂–C flux under SS, whereas Gathala et al. [14] note that, under RT, CO₂ equivalent emission is reduced by 8.4% in comparison to farmers’ practices. Along the same lines, evaluation of different tillage rotation practices are performed by Gupta et al. [37], where ZT alone and ZT+R-based wheat display significantly lower GWP and GHGs emissions compared to CT wheat, signifying that the adoption of SS practices could reduce the GWP of the conventional RW system by 44 to 47%, without compromising the yield. Similar findings are documented by Tirol-Padre et al. [22], Kakraliya et al. [34], Kar et al. [93], and Singh et al. [95]. Aryal et al. [96] employ the Cool Farm Tool (CFT) to estimate GHG emission, which utilizes data regarding total production area, productivity, and management input with pedo-climatic conditions, and the results suggest that CO₂ emissions in CT wheat are significantly higher (0.6 Mg of CO₂ eq ha⁻¹ yr⁻¹) in contrast to ZT wheat, where 0.084 Mg of CO₂ eq ha⁻¹ yr⁻¹ is sequestered. When the collective emissions from a ZT-based wheat production system are converted intoaCO₂ equivalent, the resultant produce is nearly carbon-neutral, as N₂O emissions are counterbalanced by C sequestration [93]. As tillage management practices significantly influence soil C stock, variations in GHGs emissions could certainly be attributed to the SS and CT practices. Any reduction in GHG emissions while practicing SS might also result from the restricted disposal of crop debris through burning, which is quite common in conventional practices; moreover, it is worth mentioning that burning each ton of crop residue can emit 40 g of N₂O, which is equivalent to 12.4 kg of CO₂, along with 2.3 kg of CH₄, which equals 48.3 kg of CO₂ [97].

8. Cost Savings and Profitability of Surface Seeding

Rice–wheat cropping systems need to upgrade their cost competitiveness in the perspective of trade liberalization and swift non-agricultural growth. Surface seeding plausibly involves cost-effectiveness in terms of energy, water, labor, and other inputs. This system significantly reduces machinery usage for the tillage operation and the associated cost, which is a major contributor to the cost of crop production in the IGP. Available studies collectively highlight the profitability of SS-based wheat cultivation over CT (

Table 10. Effects of surface seeding of wheat in economic aspects grown in different regions of India.

Location	Soil Type	Benefit: Cost Ratio	Increase over Conventional Practices (%)	Reference
Bihar	SL	2.3	17	[18]
Haryana	-	2.3	16	[104]
	Loam	3.6	31	[32]
Madhya Pradesh	CL	2.4	41	[22]
Uttar Pradesh	SL	3.7	64	[41]
	SL	3.1	41	[43]
West Bengal	SL, CL to clay	2.2	187	[47]
	SCL	2.1	17	[48]
	SL	1.6	10	[49]
Haryana	CL	Net return: USD1278 ha−1	13	[33]
	-	Net return: USD1108 ha−1	21	[12]
Punjab	SL	Net return: USD 621 ha−1	Benefits: USD 167 ha−1	[40]
Uttar Pradesh	SCL	Net return: USD 395 ha−1	Benefits: USD 29 ha−1	[65]
Bihar	-	Returns to capital: INR 3.0 INR−1	27	[31]
Uttar Pradesh	-	Cost of cultivation: USD 623 ha−1	Benefits: USD 133 ha−1	[77]
	-	Cost of cultivation: USD 620 ha−1	Benefits: USD 158 ha−1	[77]
Haryana	Silt loam	Net return: USD 1280 ha−1	22	[34]

Note: SL: sandy loam; CL: clay loam; SCL: sandy clay loam.

). There are two factors that inherently contribute to the overall profitability of SS: (i) the value of the yield increase, and (ii) the savings in production cost. In the RW systems of the IGP [9], practicing ZT wheat cultivation reduces the production cost by about USD32 ha⁻¹, particularly due to the use of less labor, less pumping of water, and, ultimately, lower diesel fuel consumption [101]. According to Mousques and Friedrich [96,97,100], the net income under SS is reportedly twice that of under CT, primarily due to the reduced cost of inputs [102,103]. The net benefit of ZT surpasses CT gross income by 11–17% [11]. Surveys encompassing farmers’ fields adopting ZT wheat systems in India [22,31,34,48] show that those who opt for ZT planting of wheat following rice yield obvious economic and social perks. The children of the farmers get extra time for their study and sports activities. Small and marginal farmers also pursue some technical and menial jobs in the nearby cities to earn extra income for their families. It becomes necessary to further increase the profitability of farmers by adopting SS, if provisions are made for giving carbon credits to them for additional SOC sequestration into the soil.

9. Future Researchable Priorities and Institutional Support

The adaptation and popularization of SS are mostly based upon more benefits than constraints, which are depicted in

Table 11. Potential benefits associated with surface seeding of wheat.

Benefits	Resulting from	Reasons
Agro-ecological benefits
Progressive suppression of weed growth	Improvement in soil structure and stability	Reduce tillage that allows weed seed in deep soil
Long-term yield increase	Reduced water and wind erosion	Reduce tillage and improve soil structure
	Increase in soil fertility and stability, and improved soil structure	Reduce tillage, improve soil cover due to mulching, intercropping, and crop rotation
	Improved retention of water, nutrients, and soil moisture	Reduce tillage, improve soil cover due to mulching
Reduces run-off	Decrease in erosion, improved soil structure and water-retention capacity	Reduce tillage and improve soil cover
Improves rooting conditions	Increase in soil fertility stability, and improved soil structure	Reduce tillage, improve soil cover due to mulching, intercropping, and crop rotation
Improves agrobiodiversity	Higher biological activity in the soil and in the field	Improved soil cover due to mulching
	Crop diversification	Crop rotation and intercropping
Output stability	Reduced vulnerability to climatic shocks	Improved rooting conditions
	Enhanced biological pest and disease control	Crop rotation
		Higher biological activity in the soil and in the field
Reduces waste of water and inputs	Reduced run-off	Decrease erosion, improve soil structure and water retention capacity
Environmental benefits
Decrease in land degradation	Reduced dust particles, aerosol, and other particulate material	Reduce tillage, improve soil cover, mulching, intercropping, and crop rotation
	Improved agrobiodiversity	Higher biological activity in the soil and in the field
Reduces downstream sedimentation and siltation	Reduced run-off	Decrease erosion, improve soil structure and water retention capacity
Reduces contamination of soil, and surface and ground water	Reduced run-off	Decrease erosion, improve soil structure and water retention capacity
Reduction in CO2 emissions to the atmosphere	Higher carbon sequestration	Reduce tillage, improve soil cover, and mulching
	Higher biological activity	Improve soil cover and mulching
Socio-economic benefits
Increases food security	Long-term yield increase and output stability	Reduce erosion, greater soil arability, improve soil structure, field capacity, and nutrient retention
		Enhance biological pest and disease control
	Crop diversification	Reduce vulnerability to climatic shocks
		Compatibility with various farming systems and agro-ecological environments
Increases net profitability	Long-term yield increase and output stability	Reduce erosion, greater soil arability, improved soil structure, field capacity, and nutrient retention
		Enhance biological pest/disease control
		Reduce susceptibility to climatic fluctuations
	Reduction in on-farm costs	Cost-effective labor, machinery, and (in the medium-term) chemical inputs (herbicides, fertilizer, and pesticides, depending on the technology adopted)
Technological sustainability	Compatibility with different farming systems and agro-ecological environments	An appropriate integration of cultivation techniques, equipment, and inputs

and

Table 12. Potential constraints to the adoption of surface seeding of wheat.

Constraints	Resulting from	Management Strategy
Management Constraints
Short-term pest and disease problems	Variation in crop management	Development of suitable technology and training programs
	Increased usage of soil cover/mulching	Disease control through IPM technique
		Bio intensification and application of additional green chemicals
Short-term weed infestation	Alteration in crop management	Formulating appropriate technology packages and training
	Modified tillage techniques	Additional incorporation of suitable chemicals at the critical growth stage of weed
		Additional labor and drone-based application
Limited management skills	Need to carefully plan the crop rotations and intercropping, cover crop preferences, new approaches to weed control and pest management, appropriate application of chief SS principles, etc.	Technical support
		Farmers’ participation in learning and experimentation
		Devising proper training programs
		Creation and operation of farming groups, research, and extension networks
High perceived risk (country specific)	Technology shift	Appropriate use of rewards/incentives
		Designing appropriate technology packages and training
	Inadequate management skills	Farmers’ involvement and time commitment to learning and experimentation
	Lack of country specific knowledge and information	Technical and institutional support
		Commitment of extension officers and innovative farmers
	Cultural barriers and/or community prejudice	Community involvement in training/ demonstrations and technology adaptation
Economic Constraints
Additional startup costs	Procurement of specialized planting equipment	Better access to certain markets
	Farmers’ participation in learning and experimentation	Appropriate use of rewards and incentives
	Additional labor requirements at initial stages	Expansion of suitable technology packages and training
Lower yields at initial stages	Initial immobilization of nutrients	Intercropping with leguminous/ nitrogen-fixing crops
		Supplementary fertilizer application
	Short-term problems related to pests, weeds, and diseases	IPM training and biological pest/ disease control
		Administration of additional chemicals and labor
		Devising appropriate training and technology packages
	Inadequate management skills	Technical support and extension
		Farmers’ participation and time commitment to experimentation/learning
		Creating operational farming networks and research/extension groups

. The above-presented literature review specifies a few researchable themes and strategies for the wide-ranging adoption of SS practices in the IGP, which are outlined below:

• Screening of wheat genotypes suitable for the SS could help in the proper crop establishment under sub-optimal soil moisture;
• Development of proper package of practices specifically for SS. Research and long-term field experiments on the methodology of nutrient application, weed management, and irrigation scheduling are the need of the hour;
• Development of light-weight harvesting machineries suited for SS, and its supply on subsidized rates to the marginal and small farmers;
• Development of handheld and field-specific machines for small and marginal farmers that promote SS and residue management, which are easy to operate and accepted by the farming community;
• Setting up training and demonstration campaigns by different public and private organizations for creating awareness and feasibility of SS;
• Suitable integrated weed and pest management (IWPM) strategies should be promoted via field demonstrations, as well as through active extension services;
• Surface seeding has a lack of institutional support and linkages. A close relationship among farmers and stakeholders in a participatory manner involving scientists, farmers, and farm machinery manufacturers should be initiated.

10. Conclusions

The spread of SS is mainly concentrated in the IGP of India, more particularly in eastern Uttar Pradesh and Bihar. The adoption of SS practices has the potential to increase the production of wheat, and mitigate the effects of global warming, due to less GHG emission. Additional benefits include soil health improvement, nutrient recycling, reduction in energy cost, enhanced soil WHC, reduction in run-off and erosion losses, as well as soil temperature regulation, which assists the planting of crops in rotation as per schedule. Thus, efforts are needed to change the mindset of the farmers’ through demonstrations of SS technology. This could be accomplished by extending robust technology dissemination programs, accentuating crop residue/carbon-credit retention incentives, as well as distributing suitable location-specific farm implements to procure the maximum advantages of SS techniques for the sustainable sustenance of soil health and food security. Furthermore, strong policies and legislation are essential to promote the SS technology of wheat, in order to avoid residue burning and reduce GHGs emission and other ecosystem services for a sustainable environment and healthy future. Moreover, long-term experiments on the SS of wheat should be setup under different agro-climatic regions, to find out the benefits, suitability, and impacts on the environment.