【Objective】It is of great significance to understand problems in farmers’ fertilizer application and the potential to reduce the fertilizer rates, with the purpose to realize scientific fertilizer recommendation and reasonable reduction of fertilizer input in major wheat production regions of China. 【Method】A three-year long in-farm fertilization survey and collection of soil and plant samples were carried out to analyze and evaluate the fertilization status and fertilizer reduction potentials based on the wheat yield levels, nutrient requirement and soil nutrient supply capacities in major wheat production regions of China. 【Result】The average wheat grain yields were significantly and linearly correlated with their biomass, with the average to be 6.0 and 13.2 t·hm -2 for farmers over all the major wheat regions in China, respectively. However, the yields showed no significant correlation with the fertilizer application rates and soil nutrients, and the average application rates for nitrogen (N), phosphorus (P2O5) and potassium (K2O) were 191.1, 112.8 and 53.4 kg·hm -2, respectively. In the spring wheat region, the averages were correspondingly 171.7, 108.9 and 10.6 kg·hm -2, 154.3, 111.8 and 32.6 kg·hm -2 in dryland wheat region, 236.4, 128.1 and 74.0 kg·hm -2 in wheat-maize region, and 177.5, 77.0 and 71.8 kg·hm -2 in rice-wheat region, respectively. For the N, there were less farmers, only 34% over applied fertilizers in the spring wheat region, and then it was 42% in wheat-maize region, 55% in rice-wheat region, and 63% in dryland wheat region, with the low-yielding farmers to be the focus of N fertilizer reduction, the reduction potential to be 43.6%, and the average N reduction of 2.3-135.5 kg·hm -2. The problems for over P fertilizer application were more obvious, with 63%, 87%, 68% and 57% of farmers to apply excessive P fertilizer respectively in the four regions. Even at the high-yielding levels, there were still more than 50% of farmers apply excessive P fertilizer, and all the farmers need to reduce their P fertilizer, with the average reduction to be 3.8-91.1 kg P2O5 ·hm -2, and dryland wheat region of the largest reduction potential, which was 55.6% of their current P rates. Situation for K application was variable with regions. In spring wheat region, 84% of famers applied insufficient K fertilizers, with an average of 22.8 kg·hm -2 extra K2O needed to be applied. While, in dryland wheat, wheat maize and rice wheat regions, 43.2%, 25.7% and 56.0% of their current K fertilizer application should be reduced, with the low yielding farmers to be the key in K fertilizer reduction and the average reduction of 31.7-45.9 kg K2O·hm -2. 【Conclusion】Fertilizer application and its reduction potential were found to vary with the yields and regions for wheat farmers in China. Situation of excessive fertilization was more serious for low- and medium-yielding farmers. Application of N and K fertilizers should be reduced according to the wheat yield levels, and all farmers should pay special attention to their over P fertilizer application, and reduce the P application rates to reasonable levels. Fertilizer reduction potential was the highest in the dryland wheat region for N and P fertilizers, and in rice wheat region for K fertilizer.
【Objective】The objective of this study was to determine the quantity and distribution of crop straws from rice, wheat and maize production, and the contained nutrient resources in the main grain crops planting regions of China, so as to provide a scientific basis for straw fertilizer utilization and reasonable reduction of chemical fertilizer in agricultural production in China. 【Method】 Based on data/information from National Bureau of Statistics of China and published literature, the amount of crop straws and the contained nutrient resources were estimated in rice, wheat and maize planting areas. The distribution of crop straws and the contained nutrient resources, the nutrient release of straw incorporation in next-stubble crops production, and chemical fertilizer proper reduction rate of wheat production were further analyzed in different agricultural regions of China. 【Result】The results showed that the ratio of straw to grain of rice, wheat and maize in China was 1.01, 1.14 and 1.25 by estimation of literature data, respectively. The annual yield of straw of the three major grain crops in China was 653.866 million tons during 2014-2018, among which rice, wheat and maize accounted for 32.3%, 22.7% and 45.0%, respectively. The crop straws were mainly produced in North China, Middle and Lower Reaches of the Yangtze River and Northeast China, accounting for 73.3% of the total national crop straw yields. The rice straw (50.7%) was mainly distributed in Middle and Lower Reaches of Yangtze River, the wheat straw (59.0%) was mainly distributed in Northeast China, and the maize straw were mainly distributed in Northeast China (33.7%) and North China (30.4%). A large number of literature data statistics showed that the nitrogen (N) average content of rice, wheat and maize straw was 0.78%, 0.64% and 0.85%, the phosphorus (P2O5) average content was 0.42%, 0.27% and 0.53%, the potassium (K2O) average content was 2.31%, 1.53% and 1.59%, respectively, and the total nutrient content of straw (N+P2O5+K2O) was expressed as rice>maize>wheat. The nutrient resources of three major grain crops straw were 5.098 million tons of N, 2.847 million tons of P2O5, and 11.83 million tons of K2O. The distribution of total nutrient components in different agricultural areas was as follows: Middle and Lower Reaches of Yangtze River (26.0%)>North China (25.4%)>Northeast China (21.3%)>Northwest China (11.1%)>Southwest China (10.5%)>Southeast China (5.6%). The release rates of nitrogen from rice, wheat and maize straw returning to the field were 54.9%, 51.4% and 61.9%, that of phosphorus were 60.9%, 65.3% and 73.0%, and that of potassium were 90.1%, 93.3% and 92.3%, respectively, which showed as potassium>phosphorus>nitrogen. The annual amount of nutrient returned to field from three major grain crops straw (the amount of substitution of chemical fertilizer) contained 2.940 million tons of N, 1.941 million tons of P2O5 and 10.839 million tons of K2O, with a total amount of 15.72 million tons. Among them, the nutrient (N+P2O5+K2O) release from maize straw return in the next crop growing period was the highest, accounting for 44.6% of the total amount of annual nutrient return. Straw incorporation had high potential of chemical fertilizer substitution for wheat production in China. In wheat monoculture area, the total wheat straw returning to the field could substitute chemical fertilizers input rate of 4.6 kg N·hm -2, 7.8 kg P2O5·hm -2and 65.3 kg K2O·hm -2 theoretically. In the wheat-maize rotation area, the total amount of maize straw returned to the field could substitute chemical fertilizers input rate of 39.4 kg N·hm -2, 28.9 kg P2O5·hm -2and 109.9 kg K2O·hm -2 in the wheat production season theoretically. In the rice-wheat rotation area, the total amount of rice straw returned to the field could substitute chemical fertilizers input rate of 29.9 kg N·hm -2, 17.8 kg P2O5·hm -2and 145.1 kg K2O·hm -2 in the wheat production season theoretically. 【Conclusion】The annual yield of rice, wheat and maize straw in China was 211.415 million tons, 148.431 million tons and 294.020 million tons, respectively, with a total of 653.866 million tons. The straws of three major grain crops could provide 2.940 million tons of N, 1.941 million tons of P2O5 and 10.839 million tons of K2O annually under straw returning. More than 70% of straw and nutrients resources were distributed in North China, Middle and Lower Reaches of the Yangtze River and Northeast China. In the wheat production area, the total amount of straw returned from the previous crop could substitute chemical fertilizers input rate of 4.6 to 39.4 kg N·hm -2, 7.8 to 28.9 kg P2O5·hm -2and 65.3 to145.1 kg K2O·hm -2 in theory.
【Objective】The objective of this study was to clarify the major problems of nutrition management in spring wheat production and to raise the suitable way on the organic fertilizer substitution for chemical fertilizer in different provinces and regions of China, so as to provide reference for Zero Growth Action of Chemical Fertilizers and sustainable development in spring wheat production regions. 【Method】A total of 2 166 survey data were collected from farmer interview and related literature retrieval, based on which the major problems were analyzed in different spring wheat regions of China. The data in 2018 of major livestock numbers, planting area and yield of spring wheat were downloaded from the National Bureau of Statistics of China. The nutritional contents of livestock manure, wheat straw and green manure plants were checked from published literatures, then the potential of organic fertilizer substitution for chemical fertilizer in different spring wheat regions was qualified. Comprehensive considered the climate, soils and the status of organic resources, the suitable ways of organic fertilizer substitution were suggested in different spring wheat regions. 【Result】Overuse of chemical nitrogen and phosphorus fertilizer but the deficiency of potassium and organic fertilizer dressing was the major problem of nutrition management in spring wheat. Especially, it was especially serious on nitrogen overuse in western Inner Mongolia and Ningxia irrigated spring wheat. The number of large livestock and sheep in spring wheat region was accounted for about 1/3 and 1/2 of that in China, respectively. The nutrient amount of N, P2O5 and K2O from livestock manure was 238.6×10 4, 57.6×10 4and 141.0×10 4t per year respectively, accordingly the potential of organic fertilizer from livestock manure substitution for chemical fertilizer was 78.2%, 48.1% and 43.1% for spring wheat, respectively. The total amount of straw returning to farmland in spring wheat region was 410.2×10 4t per year. Available N, P2O5 and K2O in straw was 11.4, 2.5 and 31.9 kg·hm -2 returning to farmland, accordingly in-season potential of organic fertilizer from wheat straw substitution for chemical fertilizer was 4.9%, 3.3% and 22.7%, respectively for spring wheat. Green manure plants returning to farmland was enough for meeting the nutrient requirement of spring wheat if the nutrients could release to soil completely. 【Conclusion】Based on the problems of overuse and unreasonable application of chemical fertilizer in spring wheat in China, three ways of organic fertilizer substitution including livestock manure, straw returning and green manure can be selected for resolving. By application of livestock manure the substitution potential for chemical fertilizer was 78.2%, 48.1% and 43.1%, respectively. The in-season substitution potential of organic fertilizer was 4.9%, 3.3% and 22.7%, respectively. Green manure, as organic fertilizer substitution, was sufficient for nutrient requirement of spring wheat if the nutrients could release to soil completely. The suitable way of organic fertilizer substitution should consider local resource, input and technology comprehensively.
【Objective】In order to provide the fertilization basis for scientific and efficient production of dryland wheat, the effects of organic fertilizer and biological organic fertilizer replacing chemical fertilizer on wheat yield, nutrient utilization, economy and soil environment were monitored continuously for 5 years. 【Method】From 2013 to 2018 in the dryland wheat field area of Hongtong County, Shanxi Province, there were four different fertilization patterns, including farmer pattern (FP), optimized fertilizers pattern (OF), optimized fertilizers+organic fertilizers pattern (OFM), and optimized fertilizers+biological organic fertilizers pattern (OFB), which were used to analyze the effects on the yield composition, economic benefits, nutrient absorption and transfer characteristics, fertilizer use efficiency, and soil environment of dry wheat in the Loess Plateau. 【Result】(1) Compared with the FP treatment, the average nitrogen fertilizer application was reduced by 35%, and the grain yield was significantly increased by 17.2%-21.4%, and net income was significantly increased by 44.3%-54.7% under OFM and OFB treatments, respectively; compared with the OF treatment, the average nitrogen substitution rate of OFM and OFB in five years was 40%, the spike number per hectare and 1000 grain weight were increased, and the grain yield was significantly increased by 6.0%-9.8%, and net income was significantly increased by 12.9%-21.0% under OFM and OFB treatments, respectively. (2) Compared with OF treatment, the contents of nitrogen in grain was significantly increased by 9.6%-12.8%, and the contents of phosphorus in grain was significantly increased by 12.5%-17.9% under OFM and OFB treatments, respectively; the transport amount at pre-anthesis of nitrogen, phosphorus and potassium of grain and the soil absorption after bloom were also increased, especially the soil absorption of nitrogen and phosphorus after anthesis was significantly increased by 48.8%-50.5% and 70.5%-76.2% under OFM and OFB treatments, respectively.(3) Compared with the OF treatment, the agronomic efficiency and partial productivity of potassium fertilizer under OFM treatment were significantly increased by 33.9% and 6.2%, respectively. The results showed that the apparent recovery rate of nitrogen and phosphorus fertilizer was increased by 48.6% and 65.5%, the agronomic efficiency of nitrogen and potassium fertilizer up by 71.3% and 51.3%, respectively, and the partial productivity was increased by 20.3% and 10.0%, respectively. (4)Organic fertilizers and biological organic fertilizers instead of chemical fertilizer increased soil fertility (organic matter, total nitrogen, available phosphorus, available potassium contents), nitrate nitrogen residue in soil surface was significantly decreased by 9.6%-23.0%, and there was no obvious leaching phenomenon of nitrate nitrogen in 2 m soil layer after 5 years. 【Conclusion】Instead of chemical fertilizer, organic fertilizers and biological organic fertilizers could improve the absorption of nitrogen, phosphorus and potassium in wheat grain, promote the absorption of nitrogen and phosphorus in soil after anthesis, improve the utilization efficiency of fertilizer, and significantly reduce the residue of nitrate nitrogen in soil, and alleviate soil alkalization, which was helpful to improve soil fertility and ultimately obtain higher economic and environmental benefits. Therefore, it was an important measure for the efficient and sustainable production of dryland wheat fields and the development of green agriculture.
【Objective】 Substituting fertilizer by manure is a key measure to reduce the amount of chemical nitrogen (N) fertilizer while maintaining yield. However, the complex relationships among grain yield, environmental costs, and economic benefits of substituting fertilizer by manure were still not clear for wheat production. This study quantified the agronomic, environmental and economic benefits of substituting fertilizer by manure, aiming to provide a reference for the application of substituting fertilizer by manure for wheat production of China. 【Method】 In this study, the effects of substituting fertilizer by manure on the agronomic, environmental and economic benefits of wheat production in China were assessed through Meta-analysis. 【Result】Substituting fertilizer by manure did not reduce wheat yield under the condition that the use of chemical nitrogen fertilizer was reduced by an average of 43%. The replacement ratio of manure was less than 15% and 15%-30%, and the yield significantly increased by 8% and 5%, respectively; while the replacement ratio of manure was higher than 30%, the yield did not significantly increase. Net economic benefit of wheat production was influenced by the replacement ratio of manure and the type of substituted manure. The replacement ratio of manure was less than 30%, and the net economic benefit showed no significant diffidence; while the replacement ratio of manure was higher than 45%, net economic benefits decrease by 18%, 68% when using cow manure and commercial manure as substituting fertilizer. Substituting fertilizer by manure reduced NH3 volatilization by 24% in whole wheat growing season, and decreased nitrate residue by 16% at wheat harvest stage, but increased N2O emission by 32% in whole wheat growing season. Further analysis indicated that soil properties, manure types, climatic conditions, test duration, yield and fertilization level could regulate wheat yield of substituted manure. Compared with application of chemical fertilizer treatment, the grain yield in substituting fertilizer by manure increased by 4% when soil organic matter>15 g·kg -1, while there was no difference when soil organic matter<15 g·kg -1. Yield in substituting fertilizer by manure increased by 8% when soil pH<7, while there was no difference when soil pH>7. When chicken manure, pig manure and commercial organic manure was used as substituted manure, grain yield increased by 6%, 6% and 4%, respectively, while there was no difference when cow manure was considered as substituted manure. Substituting fertilizer by manure treatment significantly increased yield by 4% in the areas with annual precipitation >600 mm, but there was no difference in the areas with annual precipitation ≤600 mm. Substituting fertilizer by manure increased yield by 5% in areas with average annual air temperature>15℃, but there was no difference in the areas with average annual air temperature <15℃. The duration of the experiment, the different yield and fertilization levels could affect wheat yield of substituted manure. Compared with the application of chemical fertilizer treatment, the grain yield in substituting fertilizer by manure increased by 6% when duration of the experiment more than a decade, while there was no difference when duration of the experiment less than a decade. Yield in substituting fertilizer by manure increased by 4% when under the condition of high nitrogen application rate, while there was no difference when low nitrogen application rate. The substitution of manure at low yields significantly increased wheat yield by 9%, while the substitution of manure at medium and high yields no difference. 【Conclusion】 Substituting fertilizer by manure did not reduce wheat yield under the condition that the use of chemical nitrogen fertilizer was reduced by an average of 43%. Substituting fertilizer by manure had the potential to substantially reduce the amount of chemical N fertilizer and N loss while maintaining wheat yield, but did not increase economic income. It was very important for increasing wheat yield, protecting ecological environment and increasing economic income to adopt suitable manure types and ratio of substituting fertilizer by manure. The use of reasonable amount of chemical N fertilizer substitution and manure types had the potential to increase the yield of substituting fertilizer by manure in the areas of sufficient precipitation and high air temperature.
【Objective】The aim of this study was to clarify fertilization and requirement of nitrogen (N), phosphorus (P) and potassium (K) in spring wheat production in Yellow River Irrigation Area of Ningxia (NYRIA), so as to provide a theoretical guide for rational fertilizer reduction and application. 【Method】Based on the investigation of farmers’ fertilizer application and field fertilization experiments, farmers’ yield levels and N, P, K fertilizer application of spring wheat were analyzed, and the grain yield, yield components, and N, P, K nutrient requirement were investigated. 【Result】The average spring wheat yield of farmers was (6 985±867) kg·hm -2 in NYRIA, and the percentage of high yield farmers was 82.7%. With the increase of yield, the excessive amount of N and P was decreased, and the application rates of K was insufficient. On average, the application rates of N, P and K were 294, 162 and 49 kg·hm -2, respectively, with 97.1% of farmers over applied N by 69-114 kg·hm -2, and 20.5% of farmers over applied P by 18-42 kg·hm -2, while K inputs were generally insufficient with an amount of 30-51 kg·hm -2. The N fertilization experiment showed that shoot biomass, grain yield, harvest index and grain number per ear all increased significantly at N rates of 120-240 kg·hm -2, and all reached the highest at the application of N 180 kg·hm -2. At the same time, the amount of N, P, and K absorbed by the grain also reached to the maximum value of 168.2, 23.9, and 23.2 kg·hm -2, respectively. Nitrogen application showed no significant effect on N harvest index, the average of which was 56.5%, and tended to increase P harvest index but decrease K harvest index. Nitrogen requirement reached to 45.8 kg·Mg -1 at N rate of 180 kg·hm -2, being 19.6% higher than that of no N application. P requirement decreased from 6.0 kg·Mg -1 at no N application to 5.3 kg·Mg -1 at N rate of 240 kg·hm -2, while K requirement increased from 42.6 to 49.7 kg·Mg -1. The P experiment showed that shoot biomass and grain number per ear decreased significantly with the increase of P rates, while 1 000 grain weight and harvest index increased significantly, so there was no significant difference in grain yield over P rates. Moreover, P application improved N uptake and harvest index, being 28.6% and 27.9% higher respectively than that of no P application. Also, P fertilizer could promote P to transfer to grain because that P uptake and P harvest index were increased by 15.9% and 15.2%, respectively. However, it showed no significant effect on N and P requirement, but decreased K requirement from 68.1 kg·Mg -1 at no P application to 49.7 kg·Mg -1 at P2O5 rate of 120 kg·hm -2. The K experiment showed that the application of K had no significant effects on biomass, grain yield, harvest index, ears per hectare, and the content of N, P and K in grain. While the high K fertilizer application of 75 kg·hm -2 significantly reduced the number of grains per ear, but increased 1 000 grain weight and harvest index of N, P and K. Grain number per ear decreased by 9.1%, 1 000 grain weight increased by 7.6%, and harvest indexes of N, P and K were 57.2%, 73.5% and 7.3%, respectively. When applying 60 kg·hm -2 of K2O, the demand for N, P and K reached the highest, which was 55.3, 5.5 and 57.6 kg·Mg -1, respectively, while the demand for N and K were both significantly reduced by 20.6% and 13.7% at K2O rate of 75 kg·hm -2. It was concluded that proper application of K could increase the demand of N and K, while over application of K could reduce the demand of N and K. 【Conclusion】Reducing N fertilizer, regulating P fertilizer and properly adding K fertilizer input were still the key for spring wheat fertilization in NYRIA. The N requirement of spring wheat was ranged 38.3-57.2 kg·Mg -1, and could increase by applying the moderate amount of N, P and K fertilizer. The demand for P of spring wheat was 5.1-6.0 kg·Mg -1, which tends to increase with N rates and is not influenced by P and K amount. The K requirement of spring wheat was within 42.6-68.1 kg·Mg -1, which seems to increase with N rates and decrease with P rates, and also is reduced by high amount of K application. The suitable recommended application of N fertilizer was 120-180 kg·hm -2, which was 25%-60% lower compared with N application of farmers. Application of P fertilizer at 48-96 kg·hm -2 was more conducive to stabilize the yield of spring wheat and promote the transfer of N and P to the grain, which was reduced by 40.7%-70.3% compared with the average application of farmers. When the application of K fertilizer was 0-30 kg·hm -2, it was more benefit to stabilize the yield and increase the grain quality.
