Pathways for losses of fertilizer nitrogen from a Rhodes grass pasture in south-eastern Queensland
Pathways for losses of fertilizer nitrogen from a Rhodes grass pasture in south-eastern Queensland
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昆士兰州东南部罗德草牧场肥料氮损失的途径
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发表时间：
1975
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通讯作者：
Vr Catchpole
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作者：
Vr Catchpole
对昆士兰州东南部一个罗兹草地的地表径流水、淋溶和气体演化对氮肥损失的重要性进行了评估。田间微区装在钢管直径21厘米，60厘米深的装备，收集表面径流，施肥与15 NH 415 NO3颗粒在150公斤氮公顷-1的速率和破坏性采样后4，8，12，16和40周的施肥。测定了15 N在土壤-植物系统中的回收率、15 N在地表径流中的损失和15 N在土壤剖面中的移动。开放式牧场地块施肥与NH 4 NO3在0和150公斤氮公顷-1的利率和收获在同一时间的微型小区。结果用于计算植株顶部肥料氮的表观回收率。直径11.5 cm的卵核。和12.0cm深的土壤给予与微区相同的肥料处理，从施肥后0、4、8、12和16周开始置于气密生长室中4周，并用于测量15 N的气体损失。土壤含水量的影响，从田间持水量到淹水对这些损失进行了研究的第二系列的核心。肥料氮的表观利用率和植株顶端15 N的利用率通常远低于20%，微区土壤-植株系统中15 N的利用率始终低于50%。大部分15 N的丢失发生在前4周。一个很大的一部分，15 N从外地微区的损失没有跟踪，但结果表明，地表径流和渗滤液不应被忽视，在东南部昆士兰州牧场的氮平衡研究。地表径流一般去除不到5%的15 N，但从一个微区的损失是40%。由于淋溶造成的损失没有量化，但在60厘米以下的土层中15 N的轻微显著过量表明它们确实发生了。15 N的气态损失从淹水牧场核心达到27%，但他们是小或没有从核心与土壤含水量或低于田间持水量。需要在气密生长室中进行详细的工作，以确定与氮的气体损失相关的土壤条件，从而将实验室结果与田间条件联系起来。
The importance of surface run-off water, leaching and evolution of gases on losses of nitrogen fertilizer from a Rhodes grass pasture in south-eastern Queensland were assessed. Field microplots encased in steel tubes 21 cm in diameter and 60 cm deep were equipped to collect surface run-off, fertilized with 15NH415NO3 prills at the rate of 150 kg nitrogen ha-1 and destructively sampled at 4, 8, 12, 16 and 40 weeks after fertilizing. The recovery of 15N in the soil-plant system, losses of 15N in surface run-off and movements of 15N down the soil profile were measured. Open pasture plots were fertilized with NH4NO3 at rates of 0 and 150 kg nitrogen ha-1 and harvested at the same times as the microplots. The results were used to calculate the apparent recovery of fertilizer nitrogen by the plant tops. Pasture cores of 11.5 cm diam. and 12.0 cm deep were given the same fertilizer treatment as the microplots, placed in gas-tight growth chambers for periods of 4 weeks starting at 0, 4, 8, 12 and 16 weeks after fertilizing, and used to measure gaseous losses of 15N. The effects of soil water content ranging from field capacity to waterlogged on these losses were studied on a second series of cores. The apparent recovery of fertilizer nitrogen and the recovery of 15N in plant tops were usually well below 20%, and the recovery of 15N in the soil-plant system of the microplots was always below 50% of the amount applied. Most of the loss of 15N occurred during the first 4 weeks. A large part of the 15N lost from the field microplots was not traced, but the results demonstrated that surface run-off and leachate should not be ignored during nitrogen balance studies on pastures in south-eastern Queensland. Surface run-off generally removed less than 5% of the 15N, but the loss was 40% from one microplot. Losses due to leaching were not quantified, but a small significant excess of 15N in soil layers below 60 cm suggested that they did occur. Gaseous losses of 15N from waterlogged pasture cores reached 27%, but they were small or absent from cores with a soil water content at or below field capacity. Detailed work in the gas-tight growth chambers to define the soil conditions associated with gaseous losses of nitrogen are needed to relate laboratory findings to field conditions.