Objectives Effects of irrigation quota, green manure plantation and their interaction on crop yield and nutrient utilization were studied in wheat/corn intercropping system in Hexi oasis irrigation area to identify an appropriate water and fertilizer management mode.
Methods The experiments was conducted in a split-split-plot design with irrigation quotas (4500, 6000 and 7500 m3/hm2) as the main plots, and green manure (planting and not planing green manure) and chemical fertilizer (fertilizer and no fertilizer) as the sub−sub plots, respectively. The chemical fertilizer treatments were applied with N 525 kg/hm2, P2O5 150 kg/hm2, K2O 90 kg/hm2.
Results Compared with irrigation quota of 4500 m3/hm2, 6000 m3/hm2 and 7500 m3/hm2 significantly increased grain yield and harvest index, grain NPK uptake and NPK harvest index, N physiological efficiency for grain yield formation of wheat, NPK physiological efficiency for grain yield formation of corn and significantly decreased N requirement for 100 kg of wheat grain yield formation and NPK requirement for 100 kg of corn grain yield formation. Green manure had no significant effect on wheat and corn grain yield. Green manure significantly decreased the harvest indexes of corn seed and K. 4500 m3/hm2 + green manure and 6000 m3/hm2 + green manure had the lowest P harvest index and highest P harvest index for corn, respectively. Green manure significantly increased the NPK requirement for 100 kg of corn grain yield formation and significantly decreased the PK physiological efficiency for corn grain yield formation. Planting green manure under 4500 m3/hm2 irrigation quota further intensified the drought stress and induced a significant increase in NPK requirement for 100 kg of corn grain yield formation and a significant decrease in PK physiological efficiency for corn grain yield formation.
Conclusions Irrigation quota is the determinant for the grain yield and harvest index, NPK uptake and NPK harvest index of grain, the requirement of NPK for 100 kg of grain production and the physiological efficiency of NPK fertilizers for grain yield formation of wheat and corn in wheat/corn intercropping system of Hexi oasis irrigated area. Under deficit irrigation quota of 4500 m3/hm2, planting green manure would lead to decreased wheat and corn production and fertilizer use efficiencies in Hexi oasis irrigated area. If the irrigation quota of 6000 m3/hm2 is possible, green manure is recommended for the belt production of wheat and corn in Hexi oasis irrigated area.
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