Measured and modeled nitrogen balances in lowland rice-pasture rotations in temperate South America
Measured and modeled nitrogen balances in lowland rice-pasture rotations in temperate South America
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DOI：
10.3389/fsufs.2023.1103118
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发表时间：
2023-04
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通讯作者：
Jesús Castillo;G. Kirk;M. Rivero;Guillermo Fabini;J. Terra;W. Ayala;A. Roel;P. Irisarri;S. Haefele
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文献类型：
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作者：
Jesús Castillo;G. Kirk;M. Rivero;Guillermo Fabini;J. Terra;W. Ayala;A. Roel;P. Irisarri;S. Haefele
涉及牧场、其他作物和/或牲畜的轮作水稻系统在温带南美洲很常见，乌拉圭的水稻-牧场-牲畜系统就是一个例子，该系统结合了非常高的水稻产量和紧密的氮(N)平衡。这些系统普遍良好的养分利用效率为其他混合耕作系统的养分管理提供了一个模板，如果基本过程能够得到充分量化和理解的话。在这里，我们在乌拉圭的一个长期实验中研究了水稻-非水稻轮作中的氮素平衡，目的是对这类系统的氮素动态的DNDC模型进行参数化和测试，以便在未来的工作中使用。试验包括三个轮作：水稻连作(RI-CONT)、水稻-大豆(RI-Soy)和水稻-牧草(RI-PASS)。我们考虑了9年的N平衡数据(NBAL)，定义为所有N投入减去所有N产出；N盈余(NSURP)，定义为食品中所有N投入减去仅N产出；以及N利用效率(NUE)，定义为去除食品中N投入的比例。我们根据测量的产量和输入输出数据对DNDC进行了参数化，从N平衡中推断出N损失的缺失数据，并与文献值进行了比较。使用平均误差、一致性和效率等标准指数对模型的性能进行了评估。该模型较好地模拟了作物产量和水稻累积吸氮量，并较好地模拟了土壤氮素。RI-CONT和RI-Soy的NBAL值分别为+45和−20 kg N ha−1年−1，RI-PASS(−6 kg N ha−1年−1)的NBAL值接近于零。NSURP值按RI-CONT>；>；RI-SOY>；RI-PASS顺序递减(分别为+115、+25和+13 kg N ha−1yr−1)。NUE值(RI-Soy、RI-Past和RI-CONT分别为84%、54%和48%)随着NBAL的增加而降低。DNDC的预测对不同作物、轮作和水分状况的农艺特性的敏感性与预期一致。我们的结论是，本文所建立的DNDC模型适合于探索如何优化这些系统中的N管理。
Rotational rice systems, involving pastures, other crops and/or livestock, are common in temperate South America, exemplified by the rice-pasture-livestock system of Uruguay which combines very high rice yields with tight nitrogen (N) balances. The generally good nutrient use efficiency in these systems provides a template for nutrient management in other mixed farming systems, if the underlying processes can be sufficiently well quantified and understood. Here, we studied N balances in rice–non-rice rotations in a long-term experiment in Uruguay, with the aim of parameterizing and testing the DNDC model of N dynamics for such systems for use in future work. The experiment includes three rotations: continuous rice (RI-CONT), rice-soybean (RI-SOY) and rice-pasture (RI-PAST). We considered 9 years of data on N balances (NBAL), defined as all N inputs minus all N outputs; N surplus (NSURP), defined as all N inputs minus only N outputs in food products; and N use efficiency (NUE), defined as the fraction of N inputs removed in food products. We parameterized DNDC against measured yield and input and output data, with missing data on N losses inferred from the N balance and compared with literature values. The model performance was assessed using standard indices of mean error, agreement and efficiency. The model simulated crop yields and rice cumulative N uptake very well, and soil N reasonably well. The values of NBAL were +45 and−20 kg N ha−1 yr−1 in RI-CONT and RI-SOY, respectively, and close to zero in RI-PAST (−6 kg N ha−1 yr−1). Values of NSURP decreased in the order RI-CONT >> RI-SOY > RI-PAST (+115, +25 and +13 kg N ha−1 yr−1, respectively). Values of NUE (84, 54, and 48% for RI-SOY, RI-PAST, and RI-CONT, respectively) decreased as NBAL increased. The sensitivity of DNDC's predictions to the agronomic characteristics of the different crops, rotations and water regimes agreed with expectations. We conclude that the DNDC model as parameterized here is suitable for exploring how to optimize N management in these systems.