Ammonia Volatilization from Soil-Applied Organic Fertilizers

ABSTRACT: A reliable quantification of nitrogen (N) losses by ammonia (NH3) volatilization can contribute to identifying optimized strategies of fertilizer management. The objective of this study was to quantify ammonia volatilization from several organic N sources incorporated into or applied onto the soil surface. Two cultivation areas, under snap bean and corn, were evaluated at Embrapa Agrobiology, Seropédica, Rio de Janeiro (RJ). Both experiments used a randomized complete block design in split-plots, with four replications. The main plots consisted of four organic fertilizers (castor bean cake, bokashi, legume fertilizers, cattle manure), at rates of 200 kg ha-1 N, and a control treatment (without fertilization), and the subplots corresponded to the management forms (incorporated or surface-applied) of the fertilizers. In the first experiment, snap bean cv. Novirex was grown in winter/spring and in the second, corn cv. Catingueiro in summer/autumn. In each subplot, static semi-open NH3 collectors were installed. We conclude that surface-applied castor cake was the organic fertilizer with highest N loss by NH3 volatilization. A comparison of the management systems (incorporated or surface-applied) showed that volatilization from organic fertilizers incorporated into the soil was significantly lower, with a reduction of 80 % for castor cake, of 78 % for bokashi and 67 % for legume fertilizer. Nitrogen loss through ammonia volatilization varied, from rates of 3 to 25 % in winter/spring and from 2 to 38 % in summer/autumn, according to the organic fertilizer applied. The period required to recover 95 % of the N lost by NH3-N volatilization was between 13 to 18 days for castor cake; 14 to 43 days for bokashi; 17 to 49 days for legume fertilizer and more than 43 days for cattle manure.

摘要：精准量化氨（NH3）挥发导致的氮（N）素损失，有助于筛选优化的肥料管理策略。本研究旨在量化多种施入土壤或表施的有机氮源的氨挥发损失量。本研究在位于里约热内卢州塞罗佩迪卡市的巴西农业生物研究中心（Embrapa Agrobiology）开展，分别设置菜豆和玉米两个种植试验区。两项试验均采用裂区随机完全区组设计，设置4次重复。主区设置4种有机肥料（蓖麻饼肥（castor bean cake）、bokashi堆肥（bokashi）、豆科绿肥（legume fertilizers）、牛粪肥），施氮量均为200 kg·ha⁻¹，另设不施肥对照处理；副区则对应肥料的施用方式（施入土壤或表施）。第一项试验于冬春季节种植菜豆品种cv. Novirex，第二项试验于夏秋季节种植玉米品种cv. Catingueiro。每个副区内均安装静态半开放式氨（NH3）收集器。研究结果表明，表施蓖麻饼肥的氨挥发氮素损失量在所有有机肥料中最高。对比两种施用模式（施入土壤与表施）的结果显示，施入土壤的有机肥料氨挥发量显著更低：蓖麻饼肥的挥发量降低80%，bokashi堆肥降低78%，豆科绿肥降低67%。不同有机肥料的氨挥发氮素损失率存在差异：冬春季节为3%~25%，夏秋季节为2%~38%。氨态氮（NH3-N）挥发损失量累计达到总损失95%所需的时长分别为：蓖麻饼肥13~18天，bokashi堆肥14~43天，豆科绿肥17~49天，牛粪肥则超过43天。