Study on Comprehensive Utilization of Crop Straw and Spatial Distribution of Cattle and Sheep in China: 1978–2023

Abstract

This study aims to assess how the supply of straw feed in China has changed over time and how this affects cattle and sheep farming. This paper takes the 31 provinces (autonomous regions and municipalities directly under the Central Government) in China as basic units. Based on the grass-to-grain ratios of different crops, the analysis includes estimating the theoretical supply of straw feed, evaluating its livestock carrying capacity, and examining the spatial distribution of supply and demand. From 1978 to 2023, the adaptability of the supply and demand of crop straws has shown a significant upward trend, but the overall adaptability is still low. Differences in the spatial layout of agriculture and animal husbandry have led to the emergence of advantageous areas for the allocation of the supply and demand of straw feeds, which are shifting from the east to the west and from the south to the north and concentrating from the planting areas to the livestock breeding areas. This study finds that climate warming has shifted the centroid of theoretical straw supply northward, resulting in higher straw–livestock compatibility in agriculturally developed regions but lower compatibility in unbalanced agro-pastoral zones, primarily due to high transport costs for straw and roughage, which constrain sustainable agro-pastoral circular development. Therefore, it is recommended that all countries (regions) actively implement the “Straw-to-Meat” policy in agriculturally advanced zones, while proactively adapting to climate warming by optimizing agro-pastoral spatial planning and exploring alternatives to roughage or expanding feed grain cultivation.

1. Introduction

The resource utilization of crop straws promotes the diversification of waste utilization and alleviates problems such as air pollution and damage to soil and water caused by the burning and discarding of crop straws. It is one of the important aspects of the green circular development of agriculture and animal husbandry and has an impact on the sustainable development of agriculture. Denmark generates electricity by burning crop straws biologically, meeting the electricity needs of more than 100,000 domestic users every year. The United Kingdom degrades crop straws through microorganisms, and the United States conducts ammoniation treatment on crop straws. These measures have increased the digestibility of crop straws to over 40% and also enhanced the nutritional value of crop straw feed [1]. China has been implementing the “Straw to Meat” initiative for many years, with ten provinces (autonomous regions and municipalities) introducing specific policies to support this program. For example, Neimenggu processed more than 8000 tons of crop straws into roughage for feeding 43 million sheep, which improved the utilization rate of straw and saved 8 million tons of grain annually. Taking townships as units, Jilin Province established an industrial chain of “collection, storage and transportation, processing, and sales” of straws, promoting the resource-based utilization of straws. Anhui Province formed an expert team for the “transformation of straws into meat” and continuously tackled technical challenges to improve the comprehensive utilization efficiency of straws. Crop straw has become one of the important sources of roughage for ruminants. However, can China’s crop straw meet the dietary demands of ruminants? Are there regional disparities between the supply of crop straw and the demand for ruminant feed across different areas in China, and will these disparities evolve over time?

Crop straw is rich in a variety of minerals and organic substances [2], and converting straw into edible feed for livestock through a series of processing can optimize the feed supply structure for ruminants [3], alleviate resource and environmental constraints [4], ease the contradiction between supply and demand of food [5], and improve the cognition of resourceful utilization of straw by farmers [6]. Rice, wheat, maize, cereal grains, sorghum, pulses, potatoes, cotton, peanut, rapeseed, sesame, sunflower, hemp, and sugarcane all produce large amounts of straw [7]. With the upgrading of the consumption structure and the establishment of a compensation mechanism for straw collection, not only does the market demand for straw feed show year-on-year growth [8], but it also makes the economic benefits of straw collection and treatment gradually increase [9], and the market space for the development of straw fodderization is gradually expanding. The cultivated area for crops in China has been increasing year by year, leading to a rising trend in the theoretical resource quantity of straw. Around 2005, the straw resource quantity was approximately 650 million tons, primarily located in the middle and lower reaches of the Yangtze River and the Huang-Huai-Hai Plain [10]. By around 2010, this figure increased to about 750 million tons [11], reaching approximately 900 million tons by 2015 [12], and around 1 billion tons by 2020 [13]. These resources are concentrated in the middle and lower reaches of the Yangtze River, Northeast China, and North China, indicating that the regional distribution of straw theoretical resource quantity exhibits differences and is continuously evolving.

The alignment between the regional distribution of straw resources and the spatial structure of cattle and sheep is crucial for the efficiency of straw feed utilization. Taking the green circular development of regional agriculture and animal husbandry as an example, it has been observed in central Gansu Province that the regional distribution of straw and the spatial structure of ruminants do not match, primarily because the actual livestock carrying capacity based on collectable straw is far below the theoretical development level [14]. From 2000 to 2020, the regional distribution of straw and the spatial structure of ruminants in the Inner Mongolia Autonomous Region were not fully aligned, significantly increasing the breeding costs for herders [15]. In contrast, the regional distribution of corn straw and the spatial structure of ruminants in Northeast China are well-matched, mainly because Northeast China is a major corn-producing region with abundant and concentrated straw resources, and most farmers engage in both agriculture and animal husbandry [16]. This demonstrates that the compatibility between the regional distribution of straw and the spatial structure of cattle and sheep in China exhibits significant regional variations, and the degree of this compatibility directly impacts the economic benefits of farmers and herders.

To sum up, current related studies often focus on pastoral regions in China, revealing a mismatch between the regional distribution of straw and the spatial structure of ruminants. This paper examines the compatibility between straw feed utilization and the regional distribution of cattle and sheep across 31 provinces (autonomous regions and municipalities) in China from 1978 to 2023. Firstly, it analyzes the theoretical foundations of straw feed utilization and the regional distribution of cattle and sheep, establishing a functional relationship to assess their compatibility. Secondly, it calculates the theoretical supply of straw feed and the theoretical livestock carrying capacity based on straw feed utilization across different regions in China, exploring the spatio-temporal variations in the development potential of straw feed. Thirdly, it evaluates the compatibility between straw feed utilization and the regional distribution of cattle and sheep in various regions, identifying areas with advantages and disadvantages in this regard. Finally, from the perspective of green circular development in agriculture and animal husbandry, it proposes policy recommendations to enhance the compatibility between straw feed utilization and the regional distribution of cattle and sheep across China. The innovation of this study lies in researching the spatio-temporal adaptability between China’s crop straws and cattle and sheep through long-history cycle data, identifying the characteristics of China’s agricultural and animal husbandry layout, and providing valuable practical insights and historical references for supporting the green circular development of agriculture and animal husbandry.

2. Data Sources and Research Methods

2.1. Data Source

This paper collects data related to the production of major crops and cattle and sheep herds in China from 1978 to 2023, involving 31 provinces (autonomous regions and municipalities) and 15 major crops such as rice, wheat, maize, other cereals, beans, potatoes, cotton, peanuts, rapeseed oil, sesame seeds, other oilseeds, sugarcane, sugar beet, tobacco, and so on; the ruminants are cattle, sheep, etc. Based on the fact that deer and geese are less farmed and not representative, this paper selects cattle and sheep as the research object. The above data come from the China Statistical Yearbook 1978–2023 and statistical yearbooks of provinces (autonomous regions and municipalities), China Rural Statistical Yearbook 1985–2023, China Agricultural Statistical Yearbook 1981–2021, 60 Years of Agricultural Statistics in New China, statistical bulletins on national economic and social development of the country and provinces (autonomous regions and municipalities) in different years, as well as statistical bulletins of the Ministry of Agriculture and Rural Development and the National Bureau of Statistics, and the National Bureau of Statistics of various regions and countries. Additionally, they come from the Ministry of Rural Affairs and the National Bureau of Statistics, and the official websites of local agricultural and rural bureaus and statistical bureaus. Among them, data for individual indicators are missing for some provinces in 2023, and were calculated by the average annual growth rate in the past five years.

2.2. Research Method

2.2.1. Theoretical Supply of Straw Feed

The theoretical supply of straw for fodder is the total amount of straw resources that can be theoretically utilized as fodder for crops. The theoretical supply of straw is calculated using the straw-to-grain ratio (also known as the straw coefficient), which refers to the ratio of aboveground crop stalk production to economic production [17], and the straw-to-grain ratio varies among different crops. Some scholars conducted a detailed investigation and statistical analysis of the straw coefficients of cereal and non-cereal field crops planted in different provinces and regions of China during 2006–2010 and finally determined the straw coefficients of cereal and non-cereal field crops coincident to the measured data in the field [18,19]. The straw coefficients of cereal and non-cereal field crops that coincide with the field measurement data were finally determined, as shown in

Table 1. Grass-to-grain ratio of major crops in China.

Crop Type	Rice	Wheat	Corn	Other cereals	Beans	Potato	Cotton	Tobacco
Grass Valley	1	1.17	1.04	1.6	1.6	0.57	3	0.71
Crop Type	Peanut	Rapeseed	Sesame seed	Other oils	Hemp	sugar cane	Beet
Grass Valley	1.14	2.87	2.01	2	1.7	0.43	0.43

, and the theoretical supply of straw forage was estimated by Formulation (1):

$$S_i={\sum }_{j=1}^n{CTP}_{ij}\times {\lambda }_j,$$

(1)

where $i=1,2,3\dots \dots \dots ,31$ is for different provinces (districts and cities), $j=1,2,3\dots \dots \dots ,15$ is the category of crops, $S_i$ refers to the theoretical supply of crop straw feed in i-th province (district, city), $CP{T}_{ij}$ is the production of $j$-th crops in the i-th province (district, city), and ${\lambda }_j$ is the-grass to-grain ratio of jcrop.

2.2.2. Theoretical Carrying Capacity of Straw Feed

The theoretical livestock capacity of straw foddering is the amount of theoretical supply of straw foddering for feeding cattle and sheep. Cattle need 7 kg of roughage and 2.5 kg of straw feed per day, and sheep need 1.5 kg of roughage and 0.6 kg of straw feed per day [20,21], and the feeding cycle of cattle and sheep is 365 days [22,23]. According to this daily feeding standard, the theoretical livestock carrying capacity of straw fodderization in China is as follows:

$$T{P}_i={\displaystyle \frac{S_i\times 1000}{N_k\times T}},$$

(2)

where $T{P}_i$ denotes the theoretical livestock carrying capacity of straw fodderization in the ith province (district and city), $S_i$ is the theoretical supply of straw from different crops in the ith province (district and city), $N_k$ refers to the daily straw demand of cattle and sheep, $k=1$ for cattle and $k=2$ for sheep, and T refers to the feeding cycle of cattle and sheep of 365 days. It is worth noting that the theoretical supply of straw forage is used here instead of the amount of straw collectible resources, because the amount of straw collectible resources takes into account a variety of practical factors, such as the level of technology and the level of the economy, and is not in line with the connotation of the theoretical amount of livestock carried by straw forage.

2.2.3. Analysis of the Adaptability Between Straw Feed Conversion and Cattle and Sheep Farming

The spatio-temporal suitability of straw foddering and cattle and sheep refers to whether the spatio-temporal distribution of straw and cattle and sheep is coordinated or not, which has two main aspects: Firstly, from the point of view of ruminant feeding, the spatio-temporal difference in the theoretical and actual livestock carrying capacity of crop straw foddering is compared through the suitability, which reacts to the spatio-temporal difference in the potential of development of straw foddering livestock carrying capacity. Secondly, from the viewpoint of supply and demand of crop straw, by comparing the temporal and spatial differences between the theoretical supply of straw and the actual demand of straw feed for cattle and sheep, the temporal and spatial differences of the effective supply and demand advantages of straw feed are reacted. The above relationship can be seen intuitively in the following formula.

$$M{P}_i=6N_1+N_2,$$

(3)

$$P_i={\displaystyle \frac{{\overline{TP}}_i}{{\overline{MP}}_i}}\times 100\%,$$

(4)

$$D_i={\displaystyle \frac{(N_1\times 2.5+N_2\times 0.6)\times 365}{{10}^3}}\times 100\%,$$

(5)

$$R_i=\sqrt{{\displaystyle \frac{S_i}{{\sum }_{i=1}^{31}{S}_i}}}\times \sqrt{{\displaystyle \frac{D_i}{{\sum }_{i=1}^{31}{D}_i}}}\times 100\%,$$

(6)

$$R_i^{\prime }={\displaystyle \frac{\overline{R_i}-\overline{R_{min}}}{\overline{R_{max}}-\overline{R_{min}}}},$$

(7)

where $M{P}_i$ represents the actual livestock carrying capacity of straw feed in the i-th province (autonomous region/municipality), calculated based on the equivalence of 1 cow to 6 sheep units [24,25]. $P_i$ is the carrying capacity compatibility, which refers to the ratio between the theoretical number of cattle and sheep and the actual number of cattle and sheep in the i-th province (autonomous region/municipality), reflecting the spatio-temporal differences in the potential for straw-fed cattle and sheep farming. $D_i$ is the actual demand for straw feed for cattle and sheep, and $R_i$ is the ratio of the theoretical supply of straw feed and the actual demand for straw feed for cattle and sheep to the national relative proportion, i.e., the supply–demand compatibility. $R_i^{\prime }$ is the average supply–demand compatibility of different time periods in the i-th province (autonomous region/municipality). $\overline{R_{max}}$ is the maximum value of the supply–demand compatibility average over different time periods in the i-th province (autonomous region/municipality), and $\overline{R_{min}}$ is the minimum value of the supply–demand compatibility average over different time periods in the i-th province (autonomous region/municipality).

2.3. Study Limitations

From the perspective of the research data: Firstly, the data of some individual provinces in 2023 are missing. The data were calculated based on the average annual growth rate of the recent five years, so there may be some differences from the actual data. Secondly, ruminants include cattle, sheep, geese, and deer. Considering that in China’s ruminant farming, cattle and sheep account for more than 85%, while the breeding of geese and deer is relatively small, cattle and sheep were selected as the research objects. As a result, the calculated theoretical livestock carrying capacity of crop straws may be higher than the actual livestock carrying capacity of crop straws, and the calculated theoretical demand for crop straws by livestock may be lower than the actual demand for crop straws by livestock. From the perspective of the research method, this study calculated the spatio-temporal adaptability between crop straws and cattle and sheep through the ratio of forage to grain. However, with the improvement of a variety of technologies, crops are gradually changing towards low-lying plants, so the calculated theoretical supply of crop straws may be higher than the actual supply of crop straws. Nevertheless, overall, this study includes 15 main types of crops and 2 main types of ruminants. The calculated results are close to the actual supply of crop straws and the actual demand for crop straws by ruminants and have a minimal impact on the research results.

3. Results and Analysis

3.1. Theoretical Supply of Crop Straw Feed in China and Other Regions

As shown in Figure 1, the theoretical supply of crop straw for fodder shows an upward trend in China from 1978 to 2023, increasing from 390 million tonnes to 880 million tonnes. Among them, the theoretical supply of rice, corn, and wheat straw accounted for more than $70\%$, but the theoretical supply of rice straw decreased from $39\%$ to $23\%$ of the total theoretical supply of straw, the theoretical supply of corn stover increased from $17\%$ to $34\%$, and the theoretical supply of wheat stover fluctuated around $20\%$ of the total theoretical supply of straw. The share of wheat straw in the total theoretical supply of straw forage fluctuates around $20\%$. The proportion of the theoretical supply of oilseed and sugar crop straw in the total theoretical supply of straw forage rises slowly, and the proportion of the theoretical supply of legume and potato crop straw in the total theoretical supply of straw forage varies in an oscillating manner, which indicates that the planting structure of crops is expanding from food crops to cash crops, and the planting structure of cash crops shows a diversified development trend, which triggered the historical change of the theoretical supply of crop straw forage. As shown in Figure 2, from 1978 to 2023, the average values, maximum values, and minimum values of the theoretical supply amounts of crop straws in northern, central, and southern China all showed a trend of decreasing in a stepwise manner. At the same time, as shown in

Table 2. The 31 provinces (autonomous regions and municipalities) with concentrated distribution areas for different crop straw feeds.

Straw Category	Supply (tons)	Concentrated Provinces	Percentage
Rice straw	904,542	Heilongjiang, Jiangsu, Zhejiang, Anhui, Jiangxi, Hubei, Hunan, Guangdong, Guangxi, Sichuan	80.72%
Wheat straw	612,356	Hebei, Jiangsu, Zhejiang, Anhui, Shandong, Henan	72.33%
Corn stalks	723,699	Hebei, Inner Mongolia, Liaoning, Jilin, Heilongjiang, Shandong, Henan	66.66%
Bean straw	124,164	Inner Mongolia, Heilongjiang, Jilin, Jiangsu, Zhejiang, Anhui, Henan, Shandong, Sichuan	71.89%
Potato straw	80,193	Shandong, Henan, Sichuan, Chongqing	40.27%
Cotton straw	75,882	Shandong, Henan, Hubei, Xinjiang	64.69%
Peanut straw	57,093	Hebei, Shandong, Henan	59.31%
Rape straw	135,904	Jiangsu, Zhejiang, Anhui, Jiangxi, Henan, Hubei, Hunan, Sichuan, Guizhou	81.59%
Sugar cane stalks	72,589	Guangdong, Hainan, Yunnan	80.62%
Beet straw	18,501	Heilongjiang, Xinjiang	56.20%
Hemp straw	6212	Henan, Anhui, Hubei, Hunan, Sichuan	77.44%
Tobacco straw	7898	Henan, Hunan, Sichuan, Guizhou, Yunnan	67.48%

Note: “Percentage” refers to the proportion of the production of the corresponding category of straw in the provinces with concentrated distribution to the total amount of straw in the country for that category of crop.

, from 1978 to 2023, the theoretical resource amount of rice straw was the highest at 904,542 thousand tons, followed by maize, wheat, rapeseed, legumes, tubers, cotton, sugarcane, peanuts, beets, tobacco leaves, and hemp. The theoretical supply of straw feed for major crop-producing provinces in China accounted for more than 50% (except for tubers), indicating a significant spatial agglomeration of straw feed across regions, and the gravity center of the theoretical supply amount of crop straw for feed utilization shifts northward, which aligns with the findings of Luo Haiping et al. (2021), who explored the northward movement of maize-dominated crop cultivation due to climate change [26].

In an analysis of the key drivers for spatio-temporal variations in theoretical straw supply, the rising trend in theoretical straw supply stems from China’s 47% population growth (1978–2023) driving agricultural expansion and stringent enforcement of the 120-million-hectare (1.8 billion mu) cropland preservation policy under national food security mandates. Concurrently, increasing meat consumption has expanded crop cultivation for animal feed production, while climate-induced northward migration of planting zones has shifted the centroid of straw supply potential toward northern China. As shown in Figure 3 and Figure 4, comparing 1991–2004 with 2005–2017, China has experienced significant warming trends alongside declining relative humidity and precipitation, directly reflecting global climate change impacts that are driving the northward migration of both crop cultivation zones and the centroid of theoretical straw supply potential. However, northern China’s pastoral regions face significant straw–forage supply–demand gaps, primarily due to geographical mismatches—most straw processing occurs in crop-intensive areas, and high transport costs severely constrain inter-regional circulation given the prevailing local-market sales model.

3.2. Theoretical Carrying Capacity of Crop Straw Feed in China and Other Regions

With the increase in the theoretical supply of crop straws in China, the theoretical livestock carrying capacity for the utilization of crop straws as feed in China increased from 241.16 million to 547.33 million from 1978 to 2023, with an average annual growth rate of 1.84%. Among them, from 1978 to 2023, the theoretical animal load of crop straw fodder in 5 provinces (municipalities), namely, Beijing, Shanghai, Zhejiang, Fujian, and Hainan, showed a decreasing trend, while the theoretical animal load of crop straw fodder in the remaining 26 provinces (districts and municipalities) increased gradually, mainly because the economic development of the plantation industry in these 5 provinces (municipalities) faced the tightening of the resources and environment and the restriction of development space. As shown in Figure 5, during the four different historical periods from 1978 to 1988, from 1989 to 1999, from 2000 to 2010, and from 2011 to 2023, the theoretical livestock carrying capacity for the utilization of crop straws as feed in 31 provinces (autonomous regions and municipalities directly under the Central Government) in China was divided into four categories: less than 10 million, between 10 million and 20 million, between 20 million and 30 million, and more than 30 million. The following changing patterns were observed: from the overall spatial and temporal changes in the path of China’s crop straw fodder theoretical livestock load from the east to the north of the center of gravity, shifting from the middle and lower reaches of the Yangtze River Plain, the North China Plain, and the Sichuan Basin to the northeastern plains, Inner Mongolia pasture, and Xinjiang pasture, indicating that China’s planting industry moving northward will have a corresponding impact on the animal husbandry production areas. The Beijing, Tianjin, Shanxi, Shanghai, Zhejiang, Fujian, Hainan, Chongqing, Guizhou, Tibet, Shaanxi, Gansu, Qinghai, Ningxia, (districts and municipalities) straw fodder theoretical capacity remained less than 10 million; the Heilongjiang, Shandong, and Henan straw fodder theoretical capacity remained more than 30 million; and the Sichuan and Jiangsu fodder theoretical capacity was always in the 20–30 million range. The remaining 12 provinces (autonomous regions and municipalities) saw a slow increase in the theoretical capacity of straw foddering, which shows that there are significant spatial and temporal differences in the theoretical capacity of straw foddering among the 31 provinces (autonomous regions and municipalities) in China, and the center of gravity of the theoretical capacity of straw foddering has shown a clear tendency to shift.

3.3. Spatial-Temporal Adaptation Analysis of Crop Straw Feed and Cattle and Sheep in China and Other Regions

The research on crop straw fodderization and spatial fitness of cattle and sheep in the country and all over the world is related to both the effective use of straw fodderization and the diversification of feed source channels for ruminants, and it is also an important embodiment of the green cyclic development of the agricultural and animal husbandry industry. As shown in Figure 6, from the perspective of the law of temporal changes, the adaptability degree of the livestock carrying capacity of crop straw for feed utilization in China has been decreasing year by year from 1978 to 2023. The overall adaptability degree in China has dropped from 386% to 84%, and the adaptability degrees in the 31 provinces have all decreased to varying degrees. This indicates that the theoretical supply of crop straw for feed utilization has shifted from a situation of oversupply to one of shortage. This is mainly because the growth rate of ruminants is faster than that of crop straw feed. On the one hand, from 1978 to 2023, the average annual growth rate of the per capita disposable income of Chinese residents was 13.1%, the average annual growth rate of the per capita meat consumption of Chinese residents was 9.9%, and the average annual growth rate of grain consumption was −1.0%. After the increase in residents’ income, the consumption structure was adjusted, and more attention was paid to the intake of nutrients such as protein, which increased the number of cattle and sheep raised. On the other hand, the promotion and popularization of practical breeding technologies such as artificial insemination and short-term fattening have significantly increased the average carcass weight of cattle and sheep, thus increasing the demand for straw from cattle and sheep. At the same time, China’s crops mainly rely on the management of more than 200 million rural households. The small scale and limited output are not conducive to increasing the output of straw, which restrains the livestock carrying capacity of straw feed.

From the perspective of the spatial change pattern, the fitness of livestock carrying capacity in Tibet and Xinjiang was less than $100\%$ in 1978–1988, mainly because Tibet and Xinjiang are important pasture areas in China, with more cattle and sheep feeding; the fitness of 14 regions, including Jilin, Heilongjiang, Jiangsu, Zhejiang, Anhui, Jiangxi, Hubei, Hunan, Fujian, Guangdong and Guangxi, was higher than $100\%$ in 2011–2023, and these regions were concentrated in the Northeast Plain, the middle and lower reaches of the Yangtze River Plain and South China, which are China’s traditional cultivation advantageous areas, and the growth rate of ruminant feeding is not as fast as the growth rate of crop residue feed; the remaining 15 provinces (autonomous regions and municipalities) had a fitness gradually less than $100\%$ in 1989–2011, mainly due to three reasons: firstly, the western region is a grassland and plateau pasture area, which is a concentrated feeding area for ruminants; secondly, urban cities such as Beijing and Tianjin are not suitable for the development of field crops, and there are fewer resources of crop residues; thirdly, Shandong and Henan have succeeded the six pasture areas to become the concentration area of grass-fed animal husbandry in China [27], which has increased the demand for straw feeds year by year.

From the view of the 31 provinces (autonomous regions and municipalities), China’s overall crop straw feed supply and demand fitness level is low, mainly because of the large differences in the spatial layout of China’s agricultural and animal husbandry industries [28]. As shown in

Table 3. Comparison of supply and demand suitability of crop straw for feed, China, 1978–2023 (%).

Site	1978–1988	1989–1999	2000–2010	2011–2023	Average	Sequence
Shandong	13.05	32.30	39.92	39.30	31.14	1
Henan	10.14	28.69	44.15	39.86	30.71	2
Nei Menggu	6.89	13.16	25.30	47.07	23.11	3
Hebei	7.31	19.17	28.44	32.13	21.76	4
Sichuan	12.28	16.86	23.47	28.26	20.22	5
Xinjiang	5.69	12.21	21.05	31.39	17.59	6
Hei Longjiang	3.63	10.70	19.34	31.76	16.36	7
Anhui	6.94	14.80	19.63	20.07	15.36	8
Jiangsu	9.65	17.46	16.58	13.52	14.30	9
Hunan	4.04	9.30	17.91	22.36	13.40	10
Jilin	2.94	8.91	16.07	20.00	11.98	11
Yunnan	3.30	6.83	14.26	20.41	11.20	12
Hubei	3.66	7.99	12.42	15.46	9.88	13
Guangxi	2.49	7.61	13.71	14.96	9.69	14
Liaoning	2.63	7.49	12.72	14.78	9.41	15
Gansu	2.95	6.07	9.07	14.40	8.12	16
Shanxi	3.17	6.02	7.87	9.21	6.57	17
Shanxi	3.37	5.99	6.66	8.69	6.18	18
Jiangxi	1.75	4.80	7.53	9.97	6.01	19
Guizhou	2.10	4.31	6.71	9.07	5.55	20
Guangdong	3.54	5.19	5.46	5.47	4.91	21
Chongqing	2.35	3.74	5.15	6.70	4.49	22
Zhejiang	2.79	3.66	3.51	2.93	3.22	23
Qinghai	2.09	2.87	3.28	4.00	3.06	24
Ningxia	0.82	1.64	3.23	4.72	2.60	25
Fujian	1.70	2.75	3.08	2.71	2.56	26
Xizang	1.37	2.05	3.02	3.26	2.42	27
Hainan	0.87	1.45	2.00	1.60	1.48	28
Tianjin	0.52	1.24	1.50	1.37	1.16	29
Beijing	0.63	1.39	1.31	0.55	0.97	30
Shanghai	0.50	0.77	0.67	0.40	0.58	31

, 1978–2023 Shandong, Henan, Inner Mongolia, Hebei, and Sichuan crop straw feed supply and demand fitness is higher, with an average value of more than 20%, mainly because of the concentration of these areas. Distributed in China’s main grain-producing areas and the main producing provinces of cattle and sheep, they are important areas for the effective allocation of supply and demand of straw feed and the green cyclic development of agriculture and animal husbandry in China. Hainan, Ningxia, Fujian, Zhejiang, Guangdong, Guizhou, Jiangxi, Shanxi, Shaanxi, Ningxia, etc., are lagging behind in the development of animal husbandry economy, and the demand for ruminant straw feed is low, so the supply and demand of crop straw forage is very poorly adapted; Qinghai, Tibet, and Gansu are highland pastoral areas, where hay is the main roughage. Shanghai, Beijing, Tianjin, and Chongqing are urban agriculture, through industrial restructuring, they gradually transitioned from low-value cultivation to high-value animal husbandry [29]; the amount of straw feed available is insufficient, and the transport cost of straw feed is high, so that the supply and demand of crop straw forage is very low, so the above areas have obvious disadvantages in the spatial suitability of straw forage and cattle and sheep. Anhui, Jiangsu, Hunan, Hubei, Jilin, and Liaoning are the main grain-producing areas in China, and the theoretical supply of crop straw is high, but the development of animal husbandry is relatively lagging behind, so the supply and demand fitness of crop straw feed is low. From the above analysis, it can be found that China’s crop straw forage supply and demand fitness is higher in the provinces with developed agriculture and animal husbandry, and the provinces with uncoordinated development of agriculture and animal husbandry economy are lagging behind in the supply and demand fitness of crop straw forage, especially in the six major grain-producing provinces, such as Jiangxi, Anhui, Jiangsu, etc., where the fitness of crop straw forage supply and demand is less than $10\%$.

Combined with the above research, it can be found that in provinces with developed agriculture and animal husbandry in China, such as Jilin, Heilongjiang, Liaoning, Inner Mongolia, Henan, etc., the implementation of the policy of “transforming crop straws into meat products” has achieved practical results. Livestock breeders have reduced the procurement cost of roughage, family farms have increased their family income by selling crop straws, and crop straw processing enterprises have relied on their technological and capital advantages to process crop straws into feed and earn value-added profits. The policy of “transforming crop straws into meat products” has created both economic and environmental benefits. However, when implementing the policy of “transforming crop straws into meat products” in other regions of China, the high procurement cost of crop straws for processing enterprises and the high transportation cost of feed have restricted the resource utilization of crop straws. The experience of implementing the policy of “transforming crop straws into meat products” in China can provide a reference for other countries around the world. On the one hand, for countries (regions) where both agriculture and animal husbandry are developed, the policy of “transforming crop straws into meat products” can be implemented. Through the local and nearby sales model, crop straws can be processed into roughage and sold to cattle and sheep breeders. On the other hand, for countries (regions) where the development of agriculture and animal husbandry is unbalanced, it is not recommended to implement the policy of “transforming crop straws into meat products” because of the lack of main bodies for crop straw supply or main bodies for roughage demand, which may lead to problems such as broken and short supply chains. If crop straws are purchased across regions or roughage is sold across regions, the high costs will be unfavorable for enhancing market competitiveness. Of course, if the problem of high transportation costs can be solved, the policy of “transforming crop straws into meat products” can be implemented in regions where the development of agriculture and animal husbandry is unbalanced.

4. Discussion

4.1. Impact on the Literature

Since the reform and opening up, the central government and various regions of China have been actively promoting straw feed, and with the rapid development of agriculture and animal husbandry, China’s straw reserves and market demand for cattle and sheep have increased year by year. In view of this, this paper explores the theoretical supply of straw fodderization, theoretical livestock carrying capacity of straw fodderization, and the straw fodderization and spatial suitability of cattle and sheep in China and 31 provinces (autonomous regions and municipalities) from 1978 to 2023, and mainly comes up with the following conclusions: In the global context of promoting the sustainable development of agriculture, taking China as an example, this study explores the use of crop straws as animal feed in China since 1978–2023. It conducts a detailed analysis of the spatio-temporal dynamics between the availability of these wastes and the breeding of cattle and sheep in China. By comparing the relationship between the theoretical supply of crop straws and the actual demand for cattle and sheep feed, it explores the changing patterns of crop straw utilization and the regional distribution of cattle and sheep in China. Previous studies on crop straw utilization and cattle and sheep breeding mainly focused on pastoral areas, ignoring the development of non-pastoral areas. They also concentrated on the impacts of climatic factors, technological factors, and relevant policies, while neglecting the comprehensive influences of economic factors and social development factors. Based on previous research, our study is rooted in 31 provinces (autonomous regions and municipalities directly under the Central Government) in China. It includes a comparative analysis of major agricultural production provinces, pastoral areas, and agro-pastoral areas, and explores the regional heterogeneity of the green circular development of agriculture and animal husbandry. Relying on long-history cycle data, it provides a comprehensive and detailed explanation for analyzing the spatio-temporal characteristics of the green circular development of agriculture and animal husbandry in China. This enriches the research literature on the green circular development of agriculture and animal husbandry.

4.2. Impact on Practice

Only by reducing transportation costs can we effectively promote the utilization of crop straws as feed and achieve the green circular development of agriculture and animal husbandry. The development practice in China over the past 50 years has proved that with the northward shift of the center of crop straw supply in China, both the theoretical livestock carrying capacity of crop straws and the actual regional layout of cattle and sheep in China are moving northward. Therefore, it is necessary to promote the green circular development of agriculture and animal husbandry in regions with developed agriculture and animal husbandry. This is mainly because the transportation costs of both crop straws and feed are relatively high. Unless the government can provide corresponding subsidies or preferential transportation policies to cover the transportation costs of crop straw processing and sales enterprises, it will be difficult to effectively promote the utilization of crop straws as feed. China’s development practice provides a reference for other countries (regions) around the world to promote the green circular development of agriculture and animal husbandry. It also reminds other countries (regions) around the world to respond in a timely manner to the impact of climate change-induced northward shift of the agricultural and animal husbandry planting belts.

5. Conclusions

Since the reform and opening up, the central government and various regions of China have been actively promoting straw feed, and with the rapid development of agriculture and animal husbandry, China’s straw reserves and market demand for cattle and sheep have increased year by year. In view of this, this paper explores the theoretical supply of straw fodderization, theoretical livestock carrying capacity of straw fodderization, and the straw fodderization and spatial suitability of cattle and sheep in China and 31 provinces (autonomous regions and municipalities) from 1978 to 2023, and mainly comes up with the following conclusions: (1) With the increase in population, the demand for agricultural crops has risen, leading to an increase in the theoretical supply of crop straws. However, global warming has accelerated the northward movement of agricultural crop planting belts, causing the center of gravity of the theoretical supply of crop straws to shift northward. (2) With the changes in people’s consumption levels and consumption structures, the demand for meat consumption has increased, and with the roughage processed from crop straws it is difficult to meet the consumption demand of the livestock industry. (3) There are obvious regional differences in the adaptability degree between the supply and demand of crop straws. In regions with developed agriculture and animal husbandry, the adaptability degree between the supply and demand of crop straws is high; while in regions with unbalanced development of agriculture and animal husbandry, the adaptability degree between the supply and demand of crop straws is low.

In order to promote the green circular development of agriculture and animal husbandry in China and globally, based on the above conclusions, the following suggestions are put forward: (1) The resource utilization of crop straws is an important direction for the development of sustainable agriculture. With the expansion of the scale of agricultural crop planting, all countries (regions) should actively implement the policy of “transforming crop straws into meat products”, improve the utilization efficiency of agricultural crop waste, and enhance environmental and economic benefits. At the same time, in response to global warming, all countries (regions) should actively address the impact of the northward movement of agricultural crop planting belts on the spatio-temporal layout of crop straws and cattle and sheep, and make industrial layout plans in advance. (2) As the scale of cattle and sheep breeding gradually expands, it is necessary to not only promote technological innovation in crop straw processing to improve the digestibility and nutritional value of crop straw feed, but also actively seek alternatives to roughage, such as increasing the planting scale of feed grains. (3) It is recommended that China and all countries (regions) around the world implement the policy of “transforming crop straws into meat products” in regions with developed agriculture and animal husbandry and implement this policy with caution in regions with unbalanced development of agriculture and animal husbandry.

Of course, the temporal and spatial adaptability between crop straws and cattle and sheep is influenced by various factors such as technology, environment, climate, industrial models, policies, and farmers’ production behaviors. Moreover, these factors also exhibit regional differences, making it difficult for this study to encompass all the influencing factors. In the future, research can focus on the study of environment-friendly crop straw utilization and cattle and sheep breeding models. Additionally, attention can be paid to the impact of changes in farmers’ production behaviors on crop straw utilization and cattle and sheep breeding under the support of the “transforming crop straws into meat” policy, so as to promote the green circular development of agriculture and animal husbandry.