Data_Sheet_1_Comparative simulation of crop productivity, soil moisture and nitrate-N leaching losses for intermediate wheatgrass and maize in Minnesota using the DSSAT model.pdf

Perennial grain crops are a potential alternative source of staple foods and animal forage that can also provide additional environmental benefits over annual crops. Intermediate wheatgrass (IWG; Thinopyrum intermedium) is a new perennial dual-use crop for grain and forage, with growing interest among stakeholders as it produces grain in a more environmentally sound manner than current annual crops. DSSAT model simulations were performed for maize and a new DSSAT model for IWG based on data collected from field studies conducted during 2013–2015 at three different locations, i.e., Lamberton, Waseca and Crookston using low (zero), medium (60–80 kg ha−1) and high fertilizer nitrogen (N) rates (120–160 kg ha−1). The DSSAT CERES-Maize and CROPGRO-PFM models used as the basis for simulating IWG were calibrated at the high N rate to predict the yield/biomass, soil water balance, and soil nitrogen balance in maize and IWG, respectively, for the medium and low N rate treatments. Model predictions for maize yield and IWG biomass (0.89 >= Nash Sutcliffe Efficiency >= 0.58), soil profile moisture (0.81 >=NSE>=0.53) ranged from very good to satisfactory for maize and the high N rate in IWG, with nearly satisfactory accuracy for IWG under the medium and zero N rates. Simulation results indicate that low, medium and high N rates produced an average IWG biomass of 7.8, 9.7, and 10.5 t ha−1, in addition to observed grain yield of 0.36, 0.49, and 0.45 t ha−1, respectively. The corresponding N rates produced 5.9, 7.9, and 8.7 t ha−1 maize yield. Soil profile moisture under IWG and maize averaged 0.25 and 0.29 m3m−3, respectively. Averaged over N rates and locations, IWG and maize had values for crop evapotranspiration (ETc) of 592 vs. 517 mm; deep percolation of 100.8 vs. 154.5 mm; and nitrate-N leaching losses of 2.6 vs. 17.9 kg ha−1, respectively. Results indicate that perennial IWG not only produced high biomass under rainfed conditions, but also reduced deep percolation by efficiently using soil profile moisture, leading to nitrate-N leaching losses six to seven times lower than for maize.

多年生谷物作物是主食与动物饲草的潜在替代来源，相较于一年生作物，还能带来额外的环境效益。中间偃麦草（Intermediate Wheatgrass，简称IWG；学名*Thinopyrum intermedium*）是一种新型粮饲兼用多年生作物，因其谷物生产模式较现有一年生作物更为环境友好，愈发受到各利益相关方的重视。本研究基于2013-2015年在Lamberton、Waseca及Crookston三个试验点开展的田间试验数据，针对玉米及适配IWG的新型DSSAT模型开展了模拟研究。试验设置了低（0）、中（60~80 kg·ha⁻¹）和高（120~160 kg·ha⁻¹）三个氮肥施用量梯度。本研究以用于模拟IWG的DSSAT CERES-Maize与CROPGRO-PFM模型为基础，以高氮肥处理下的试验数据对模型进行校准，分别针对玉米与IWG的中、低氮肥处理，预测其产量/生物量、土壤水分平衡与土壤氮素平衡。模型预测结果显示，玉米产量与IWG生物量的纳什-苏特克利夫效率（Nash-Sutcliffe Efficiency, NSE）介于0.58~0.89之间，土壤剖面含水率的NSE介于0.53~0.81之间；其中玉米与IWG高氮肥处理的预测效果为良好至合格，IWG中、低氮肥处理的预测精度则接近合格水平。模拟结果表明，低、中、高氮肥处理下，IWG的平均生物量分别为7.8、9.7和10.5 t·ha⁻¹，对应的实测谷物产量则分别为0.36、0.49和0.45 t·ha⁻¹。相同氮肥梯度下，玉米的产量分别为5.9、7.9和8.7 t·ha⁻¹。IWG与玉米田的土壤剖面含水率平均值分别为0.25与0.29 m³·m⁻³。综合各氮肥梯度与试验点的数据，IWG与玉米的作物蒸发蒸腾量（crop evapotranspiration, ETc）分别为592 mm与517 mm；深层渗漏量分别为100.8 mm与154.5 mm；硝态氮淋失量分别为2.6 kg·ha⁻¹与17.9 kg·ha⁻¹。研究结果表明，多年生IWG不仅在雨养条件下可获得较高的生物量，还能通过高效利用土壤剖面含水率减少深层渗漏，最终使硝态氮淋失量较玉米降低6~7倍。