Effects of three types of soil amendments on yield and soil nitrogen balance of maize-wheat rotation system in the Hetao Irrigation Area, China

Abstract

Excessive fertilization combined with unreasonable irrigation in farmland of the Hetao Irrigation Area (HIR), China, has resulted in a large amount of nitrogen (N) losses and agricultural non-point source pollution. Application of soil amendments has become one of the important strategies for reducing N losses of farmland. However, there is still no systematic study on the effects of various soil amendments on N losses in the HIR. In this study, three types of soil amendments (biochar, bentonite and polyacrylamide) were applied in a maize-wheat rotation system in the HIR during 2015-2017. Yields of maize and wheat, soil NH 3 volatilization, N 2 O emission and NO 3leaching were determined and soil N balance was estimated. The results showed that applications of biochar, bentonite and polyacrylamide significantly increased yields of maize by 9.2%, 14.3% and 13.3%, respectively, and wheat by 9.2%, 16.6% and 12.3%, respectively, compared with the control (fertilization alone). Applications of biochar, bentonite and polyacrylamide significantly reduced soil N leaching by 23.1%, 35.5% and 27.1%, soil NH 3-N volatilization by 34.8%, 52.7% and 37.8%, and soil N surplus by 23.9%, 37.4% and 30.6%, respectively. Applications of bentonite and polyacrylamide significantly reduced N 2 ON emissions from soil by 37.3% and 35.8%, respectively, compared with the control. Compared with application of biochar, applications of bentonite and polyacrylamide increased yields of maize and wheat by 5.1% and 3.5%, respectively. Our results suggest that soil amendments (bentonite and polyacrylamide) can play important roles in reducing N losses and increasing yield for the maize-wheat rotation system in the HIR, China.

Assessing the Agricultural Water Savings–Economy–Ecological Environment System in an Arid Area of Northwest China Using a Water Rights Transaction Model

“…Negative value of greenhouse gas N 2 O emissions: The negative value of the cultivated land ecosystem produced by the use of chemical fertilizers: As a result of the low utilization rate for chemical fertilizers, the unused part accumulates or migrates into the soil over time, causing a large amount of nitrogen loss and non-point-source agricultural pollution [42][43][44]. The negative value of unused fertilizers is calculated as follows:…”

“…The value of farmland environmental pollution caused by chemical fertilizers and plastic films exceeds the value of basic services to the farmland ecosystem, which increases farmland productivity to a certain extent but also aggravates the carrying load of the farmland ecosystem [20]. Simultaneously, excessive wasteland reclamation by humans causes damage to the service function value of the original desert ecosystems, such as value associated with raw salt production, water conservation, and climate regulation [42]. The measures of returning land and reducing water have not only reduced the unreasonable use of water resources and the pollution of farmland ecological environments, but also played a positive role in reducing greenhouse gas emissions.…”

Effects of Different Soil Moisture-Holding Strategies on Growth Characteristics, Yield and Quality of Winter-Seeded Spring Wheat

“…The application of water-retaining agents and soil amendments have positive effects on improving soil structure and maintains soil water, gas and heat, finally enhancing the soil water-holding capacity [9][10][11]. For example, Wu et al showed that the application of soil amendments reduced field N losses by improving the physical structure of the soil, ultimately increasing the yield of wheat and maize [12]. The application of straw and plastic film mulching greatly inhibits soil water evaporation, which is beneficial to increase the water use efficiency [13][14][15][16].…”