Abstract
What strategy of nutrient management can maintain the high and stable annual yield in rice–wheat systems under climate change? A 10-year term experiment was conducted in the rice–wheat system to investigate the effect of optimal nutrient management on crop yield and meteorological drivers of year-to-year fluctuations in rice and wheat yield. Treatments were as follows: conventional fertilization (CF, as control), fertilizer postponing (FP, with the same amount fertilization as CF and increasing rate and times of panicle fertilizer) with/without straw incorporation (including only straw returned in rice (W) or wheat (R) season, and both straw incorporation (WS), RFP (reducing amount based on FP) with/without organic fertilizer. Results showed that FP with/without straw incorporation increased 10-year average yields of rice, wheat, and annual by 4.5~6.5%, 3.8~7.2%, and 4.8~6.8%, respectively, while RFP with/without organic fertilizer did not markedly reduce wheat yield, compared with CF. Effect of optimal treatments on wheat and rice yield stability was different; among the annual yield stability in FP + WRS was the greatest due to increasing and a stable number of spikelets and dry matter accumulation (DMA) after heading. Furthermore, the coefficient of variation (CV) of DMA during rice jointing-heading (21.6~30.0%) and heading-maturity stage (20.1~27.9%) was higher than before jointing (13.9~16.7%), which were affected by day photosynthetically active radiation (explain: 26%) and the number of rainy days (explain: 34%), respectively, using Stepwise regression; in contrast, in wheat season, the fluctuation of DMA before jointing was the highest (CV: 83.8~109.9% (before jointing) vs. 61.1~97.4% (heading-mature stage) vs. 33.7~46.3% (jointing-heading period), 55% of its variations was impacted by day-night temperature differences, the number of rainy days and photosynthetically active radiation accumulation. Our finding suggested that nutrient management to increase and stable the DMA after rice jointing and before wheat jointing could maintain the high and stable annual yield in rice–wheat systems.
Highlights
Rice and wheat are important food crops in China, accounting for 51.6% of China’s total grain yield [1]
Nutrient management significantly affected the stability of annual yield, but there was no difference between optimized treatments and CF
Our findings demonstrated differences in annual yield in the rice–wheat system among the different optimized nutrient management
Summary
Rice and wheat are important food crops in China, accounting for 51.6% of China’s total grain yield [1]. The middle and lower reaches of the Yangtze River is an important rice–wheat rotation region in China, with an area of about 3.4 million hm and an average annual grain yield of 8 t hm−2 rice and 5.5 t hm−2 wheat [2]. High production in this region is achieved by high nitrogen (N) fertilization levels (average N fertilizer rate kg N hm−2 for rice and kg N hm−2 for wheat) [3,4]. The intensity and frequency of unfavorable weather may be increased in the future due to climate change, crop yields stability being further threatened [7–9]. The selection strategy of high and stable yield in rice–wheat rotation systems is of great significance for ensuring future food security under climate change
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