稻麦农田土壤Cu累积条件下猪粪安全施用量

Safety dosage of pig manure based on soil copper accumulation on rice and wheat rotated farmland

采用田间定位试验,研究了稻麦农田猪粪替代化肥后耕层土壤重金属Cu的变化特征,并基于耕层土壤Cu年累积速率探讨了猪粪安全施用量。结果表明,水稻收获期,耕层土壤总Cu和有效态Cu含量,以及总Cu和有效态Cu的累积速率,均随着猪粪施用比例的提高呈现线性增加趋势。由耕层0~10 cm土壤总Cu年累积速率可知,稻麦农田猪粪可安全施用年限,随着猪粪施用比例的提高呈现乘幂方程的降低趋势。在农业安全生产二级标准内,20年和50年尺度上猪粪氮替代化学氮肥比例分别为50.3%~62.7%和19.1%~26.1%。据此,基于该定位试验的耕层土壤Cu累积效应,建议20年尺度上猪粪氮替代率不超过50%,50年尺度上猪粪氮替代率不超过20%。

A field experiment was conducted with different dosage of pig manure on rice and wheat rotated farmland. Five mixed soil samples were taken in the 0 ~10 cm and 10 ~20 cm soil layers in the rice harvest period in 2013 and 2014, respectively. The contents of total and available copper were determined by atomic absorption spectrometry after HF-HNO_3-HCl O4 heating digestion method and DTPA extraction method respectively to analyze the characteristic changes and accumulation rate of total and available copper under different dosage of pig manure. The analysis of pig manure safety use ages was according to the secondary standard of agricultural safety production combined with total copper annual accumulation rate of different dosages of pig manure in the 0 ~10 cm soil layer. The field experiments results clearly demonstrated that the contents and accumulation rate of total and effective copper showed a linearly increasing trend with the increased pig manure application ratio in the arable soil layer on rice harvest. By average annual accumulation rate of total copper, safety use ages of pig manure showed a decreasing trend of power equation with the increased pig manure application ratio in the 0~10 cm soil layer. Replacement ratios of pig manure nitrogen to chemical nitrogen were 50.3% ~62.7% in 20 years scale, and 19.1%~26.1% in 50 years scale according to the secondary standard of agricultural safety production. In all, based on soil copper accumulation rate, it is suggested that replacement ratios of pig manure nitrogen are less than 50% in 20 years scale, and within 20% in 50 years scale in the rice and wheat field experiment.