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首页> 外文期刊>Crop and Pasture Science >Fate of urea nitrogen in sheep urine applied to soil at different times of the year in the pasture–wheat rotation in south Western Australia
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Fate of urea nitrogen in sheep urine applied to soil at different times of the year in the pasture–wheat rotation in south Western Australia

机译：在澳大利亚西南部的牧场-小麦轮作中，一年中不同时间施用到土壤的绵羊尿液中尿素氮的命运

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Sheep urine labelled with 15N-urea was applied toconfined micro-plots at different times of the year to follow the fate of ureaN in urine in the grazed pasture-wheat rotation in south Western Australia.Three field experiments were conducted on the same site on a loamy sand.Applications were made either to pasture residues (Expts 1 and 2) which weresubsequently sown to wheat, orto growing pasture in winter-spring, (Expt 3).In Expt 1, urine was applied in November 1990 (9·8 gN/m2) and April 1991 (46·1 gN/m2). From both applications, losses of15N attributed to NH3volatilisation were c. 50% within 2 weeks of application. Another10% loss was attributed toNO-3 leaching during the followinggrowing season and 15% was recovered by the wheat crop. In Expt 2,urine was applied in October 1991 (4·6 gN/m2), January 1992 (15·6 gN/m2), and March 1992 (13·6 gN/m2). Attributed NH3 losseswithin 2 weeks, in terms of 15N-urea applied, were40% (October and January urine) and 30% (March urine) andNO-3 leaching losses were estimated to be 20% forthe 3 applications. Recoveries in wheat (November 1992) were 4, 7, and12% of 15N applied in the October, January, andMarch urine applications. In Expt 3, urine was applied in August 1992(12·3 g N/m2) and September 1992 (25·9g N/m2). Attributed NH3 losseswere 10% of applied 15N for the August and30% for the September application. Plant uptake of15N was rapid and by mid October was 42% from theAugust application and 47% from the September application. Recovery of15N in soil organic N was generally 17-25% whenurine was applied to pasture residues and bare soil,and 21-37% whenurine was applied to growing pasture. It is suggested thatNH3 volatilisation was the predominant N loss mechanism.The amount of NO-3 leached wasprimarily influenced by summer rainfall, the length of time urine-N was insoil before the onset of winter rainfall, and the distributionof winterrainfall. Little of the 15N-labelled urine was eitherrecovered by, or available for, subsequent wheat crops, suggesting thatcalculations for estimating the N supply from pastures to cereal cropsmustdiscount most N returned in urine by grazing animals
机译：在澳大利亚西南部的放牧牧场-小麦轮作中，在每年的不同时间将标记有15N尿素的绵羊尿液应用于受限的微图，以追踪尿液中尿素氮的命运。壤土砂。适用于随后播种到小麦上的草场残留物（1号和2号），或冬春季节生长的草场（3号）。1990年11月，在1号试验中，尿液被施用（9·8 gN） / m2）和1991年4月（46·1 gN / m2）。从这两种应用中，归因于NH 3挥发的15 N的损失为c。施用后2周内达到50％。另外10％的损失归因于随后生长季节的NO-3淋洗，小麦作物回收了15％。在Expt 2中，分别于1991年10月（4·6 gN / m2），1992年1月（15·6 gN / m2）和1992年3月（13·6 gN / m2）使用尿。就施用的15N尿素而言，两周内应归因的NH3损失分别为40％（十月和一月尿）和30％（三月尿），这3种施用的NO-3淋失损失估计为20％。小麦（1992年11月）的回收率分别为10月，1月和3月尿液施用量的15N的4、7和12％。在Expt 3中，1992年8月（12·3 g N / m2）和1992年9月（25·9g N / m2）使用了尿液。归因于NH3的损失是8月申请的15N的10％和9月申请的30％。植物吸收15 N的速度很快，到10月中旬，从8月的施用量中占42％，从9月的施用量中占47％。当在草场残留物和裸露的土壤上施用尿素时，土壤有机氮中15 N的回收率通常为17-25％，而在生长的草场上使用尿素时其回收率则为21-37％。认为NH3挥发是氮流失的主要机制。NO-3的淋失量主要受夏季降雨，冬季降雨开始前尿N在土壤中的停留时间长短以及冬季降雨分布的影响。 15N标记的尿液很少被随后的小麦作物回收，或可用于随后的小麦作物，这表明估算牧场中谷物作物的氮供应量的计算必须使放牧动物尿液中返回的氮量最多。

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