Effect of different nitrogen rates and use of DMPP nitrification inhibitor on N2O emissions from maize in sub-tropical Ferrosols. Kingaroy, Queensland, 2011-2012 [Theme 1: Inhibitors for reducing emissions]

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施氮水平，以及硝化抑制剂3,4-二甲基吡唑磷酸盐（3,4-dimethylpyrazole phosphate，DMPP，商品名为Entec）对亚热带夏季玉米田氧化亚氮（N₂O）排放的减排效果。同时，为评估各处理的经济可持续性与氧化亚氮排放强度，本研究重点关注了不同施肥处理的产量响应。
田间试验设于澳大利亚昆士兰州东南部金格罗伊（Kingaroy, S-E QLD）的弱发育铁铝土（euchrozems Ferrosol）土壤中，采用随机完全区组三重复设计，每个处理设置3次重复。
本试验共设置4组处理，涵盖3种施氮水平与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）、次优施氮量处理（L2：100 kg-N ha⁻¹ - 常规尿素）、常规尿素最优施氮量处理（L3：160 kg-N ha⁻¹ - 常规尿素）以及DMPP尿素最优施氮量处理（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。为深入阐明农业土壤中温室气体产生与释放的动态影响机制，研究持续监测了监测舱内的空气温度与土壤水分。为对比4组处理的环境绩效，本研究同时测定了谷物产量以评估农艺可持续性。