As the livestock numbers on Finnish dairy farms have increased and most fields on dairy farms are under grass, it has become common to spread cattle slurry over grasslands. To estimate environmental effects of recurrent slurry applications, a 5-year field study was performed to compare nitrogen (N) losses to water and ammonia losses to air by volatilization, when cattle slurry was either surface broadcast or injected into clay soil after grass cuttings. Slurry was spread on the grass in summer (1996–1997) or both in summer and autumn (1998–2000). Biomass N uptake before grass harvesting and amount of soil mineral N in spring and autumn were measured and field N balances were calculated. Despite cool weather, up to one third of the ammonium N of broadcast slurries was lost through ammonia volatilization after application in autumn, but injection effectively prevented losses. The mean surface runoff losses of total N were negligible (0.3–4.6 kg ha-1 yr-1) with the highest loss of 13 kg ha-1 yr-1 measured after slurry broadcasting to wet soil in autumn and followed with heavy rains. A substantial part (24–55%) of the applied mineral N was not recovered by the foregoing measurements.
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机译:随着芬兰奶牛场中牲畜数量的增加,并且奶牛场中的大多数田地都在草丛中,将牛粪浆撒到草原上已变得司空见惯。为了估算经常使用泥浆的环境影响,进行了为期5年的野外研究,比较了牛粪浆表面播撒或在cutting插后注入粘土中时,挥发引起的氮(N)损失对水的损失和氨损失对空气的损失。在夏季(1996-1997年)或夏季和秋季(1998-2000年)都在草地上撒浆。测量收获前的生物量氮和春季和秋季的土壤矿质氮含量,并计算田间氮平衡。尽管天气凉爽,秋季施用后,氨气挥发仍损失高达三分之一的N广播浆液中的N,但注入可有效防止损失。总氮的平均地表径流损失可以忽略不计(0.3–4.6 kg ha-1 yr-1),其中最大的损失是在秋季将泥浆播撒到湿润的土壤中,随后是暴雨之后,损失了13 kg ha-1 yr-1。前述测量未回收到相当一部分(24-55%)的施用矿质氮。
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