Effect of different nitrogen rates and use of DMPP nitrification inhibitor on N2O emissions from maize in sub-tropical Ferrosols.

The objective of this experiment was to investigate the role of different N fertilization rates and the use of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP, commercially sold as Entec) in reducing N2O emissions from subtropical maize systems over summer. At the same time, particular attention was given to the yield response shown by the different treatments, in order to evaluate the respective economical sustainability and N2O intensity. The field experiment was set up in Kingaroy ( S-E QLD), on a euchrozems Ferrosol soil, using a randomized complete three-block design (three replicates per treatment). The four treatments encompassed three different fertilization rates and two types of Urea (conventional and DMPP urea): control treatment (L1: 40 kg-N ha-1 -conv. urea), sub-optimal N rate (L2: 100 kg-N ha-1 –conv. urea) and optimal N rate (L3: 160 kg-N ha-1 –conv. urea, L4: 160 kg-N ha-1 –DMPP urea). The N2O emissions were measured from planting (December 20th 2011) to harvest (June 20th 2012) with a fully automated greenhouse gas measuring system. In order to gain optimum understanding of the dynamics influencing greenhouse gas production and release in agricultural soils, the air temperature and the soil moisture inside the measuring chambers were constantly monitored. To compare the "environmental" performances of the four treatments with agronomical sustainability grain yields were also determined.

本试验旨在探究不同氮肥施用量与硝化抑制剂（nitrification inhibitor）3,4-二甲基吡唑磷酸盐（3,4-dimethylpyrazole phosphate，DMPP，商品名Entec）在夏季亚热带玉米种植系统中削减一氧化二氮（N₂O）排放的效果。同时，重点关注各处理的产量响应，以评估其经济可持续性与N₂O排放强度。田间试验设于昆士兰州东南部金格罗伊（Kingaroy, S-E QLD）的euchrozems Ferrosol土壤上，采用随机完全区组设计，每个处理设置3次重复。本试验共设置4种处理，包含3种氮肥施用量与2种尿素类型（常规尿素与DMPP尿素）：对照处理（L1：40 kg N·ha⁻¹，常规尿素）、次优氮肥施用量处理（L2：100 kg N·ha⁻¹，常规尿素）、最优氮肥施用量处理（L3：160 kg N·ha⁻¹，常规尿素；L4：160 kg N·ha⁻¹，DMPP尿素）。试验周期为2011年12月20日播种至2012年6月20日收获，期间采用全自动温室气体监测系统测定N₂O排放通量。为深入理解农田土壤中温室气体产生与释放的动力学机制，研究人员同步监测了测定箱内的空气温度与土壤湿度。为对比4种处理的环境表现与农艺可持续性，本研究同时测定了籽粒产量。