Responses of Winter Wheat Production to Green Manure and Nitrogen Fertilizer on the Loess Plateau

Abstract

Scant rainfall and poor soil fertility are the two major obstructions to crop production on the Loess Plateau. To improve crop productivity and to reduce N fertilizer rates, a 4‐yr field experiment was conducted to investigate the effects of leguminous green manure (GM) and N fertilizer on winter wheat ( Triticum aestivum L.) growth, yield, and economics on the Loess Plateau. Following a split‐plot design, the main treatments included three legume species: Huai bean ( Glycine ussuriensis Regel et Maack.), soybean [ G. max (L.) Merr.], mung bean ( Phaseolus radiatus L.), and summer fallow (as control treatment [CK]); The subtreatments included four N fertilizer rates that were applied to the wheat. Leguminous GM apparently improved wheat growth, productivity, and nutrient uptake compared to bare fallow, especially during a wet year. At least 2 yr and abundant rainfall are required for bettering the GM approaches. Incorporation of GM for 4 yrs could effectively reduce the N fertilizer rate for wheat by 33% (54 kg N ha −1 ), with even more potential during a wet year. High expenditures for field management and variable weather patterns led to few direct economic benefits of GM approaches. Huai bean is a more profitable legume species to be used as GM crops. The cultivation of leguminous GM during summer is a better option than bare fallow for sustaining wheat productivity, and decreasing the required N fertilizer rates not only on the Loess Plateau of China but also in the other similar dryland regions around the world.