Agronomic and environmental causes of yield and nitrogen use efficiency gaps in Chinese rice farming systems
Agronomic and environmental causes of yield and nitrogen use efficiency gaps in Chinese rice farming systems
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DOI：
10.1016/j.eja.2017.11.001
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发表时间：
2018-02-01
影响因子：
5.2
通讯作者：
Fan, Mingsheng
中科院分区：
文献类型：
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作者：
An, Ning;Wei, Wenliang;Fan, Mingsheng
产量(YG)和氮素利用效率(NUE)差距分析是解决农业系统可持续集约化的关键工具。区分和量化造成这些差距的根本的农学和环境原因与估计其严重程度同样重要。我们应用了一个田间试验框架，该框架允许我们划分由于作物管理、气候因素和/或固有土壤生产力而造成的YGs和NUE缺口。YG和NUE缺口是指标准农场措施下的产量和NUE与最佳管理措施下可获得的产量和NUE之间的差异。在中国的农户田里，水稻的平均产量为1900千克公顷(-1)，氮肥利用率为18千克(-1)。然而，由于关键的农艺和环境变量，两者在不同的水稻耕作系统内和不同水稻耕作系统之间都有很大的差异，中低产田和单一水稻系统的差距更大。优化氮水管理、增加水稻插秧密度等管理措施，平均使稻谷缩小38%，氮素利用效率差距平均缩小39%。基于气候(YG-C)和土壤内在生产力的YG(YG-S)代表了来自气候和土壤变异的YG，在单季中低产田平均占YG的16%和38%，在早稻和晚稻分别增加14%和27%，11%和20%。早稻生长度日(GDD)和晚稻日最低气温(T-min)是预测YG-C的最佳因子。对于长江三角洲的单季水稻，YG-C包含了较低的日平均气温和GDD，以及较高的日最高气温和水稻生育期降水量等多个因素。土壤养分供应能力是YG-S在那些表现不佳的农田中的部分原因。氮素利用率较高的水稻具有显著的增产潜力，特别是在中低产田。然而，国家和区域农业政策应更多地强调支持良好的农艺和土壤管理，从而在水稻耕作系统中走向土壤-气候智能管理方法。
Yield (YG) and nitrogen use efficiency (NUE) gap analysis is a key tool in addressing the sustainable intensification of agricultural systems. Distinguishing and quantifying the underlying agronomic and environmental causes of these gaps is as important as estimating their magnitude. We applied a field experimental framework that allowed us to partition YGs and NUE gaps due to crop management, climatic factors and/or inherent soil productivity. YG and NUE gaps were determined as the differences between yields and NUE under standard farm practices and the attainable yield and NUE using optimum management practices. In farmers fields in China, the rice YG and NUE gap (expressed as the partial factor productivity of applied N, namely kg rice grain per kg fertilizer N applied, PFPN) averaged 1900 kg ha(-1) and 18 kg kg(-1), respectively. However, both were subject to large variability within and across different rice farming systems in response to key agronomic and environmental variables, with larger gaps in moderate- and low-yielding fields and in single rice systems. Management practices such as optimizing N and water management and increasing rice transplanting density simultaneously narrowed the YG by 38% and the NUE gap by 39% on average. Climatic- (YG-C) and inherent soil productivity-based YGs (YG-S), which represented fractions of YG derived from climate and soil variability, accounted for on average 16% and 38% of the total YG across low- and moderate-yielding fields in single rice systems, and by 14% and 27% in early and 11% and 20% in late rice farming systems, respectively. Growing-degree days (GDD) for early rice and daily minimum temperature (T-MIN) for late rice were the best predictors of YG-C. For single rice in the Yangtze Delta, YG-C included multiple factors such as lower daily mean temperature and GDD, and higher daily maximum temperatures and precipitation during rice growing periods. Soil nutrient supplying capacity was partially responsible for YG-S in those under-performing fields. Significant and exploitable potential exists for increasing rice productivity with higher NUE, especially in moderate- and low-yielding fields. However, national and regional agricultural policies should place more emphasis on supporting good agronomy and soil management, thus moving towards a soil-climate smart management approach in rice farming systems.