氮肥基追比对小麦产量、土壤水氮分布及利用的影响

为解决区域土壤质地类型针对性氮肥施用问题,在轻壤土和黏壤土上分别设置不施氮肥,氮肥基追比3∶7,4∶6,5∶5,6∶4和7∶3处理,研究小麦产量、水氮利用效率以及土壤含水量、贮水量、NH_4~+-N、NO_3~--N动态变化规律。结果表明:轻壤质土壤氮肥基追比4∶6的处理小麦产量、水分利用效率、氮肥生产效率最高分别为8 265.3 kg/hm~2,27.6 kg/(hm~2·mm),34.4 kg/kg。黏壤质土壤氮肥基追比5∶5的处理小麦产量、水分利用效率、氮肥生产效率最高分别为8 363.2 kg/hm~2,28.3 kg/(hm~2·mm),34.8 kg/kg。小麦不同生育期各土层含水量垂直分布变化较大,轻壤质土壤含水量在9.3%～26.2%,而黏壤质为9.7%～27.6%;小麦全生育期内土壤贮水量呈先升高后降低趋势,黏壤质土壤贮水量高于轻壤质。氮素追施量越多土壤表层NH_4~+-N与NO_3~--N含量越高,且随土层加深土壤NH_4~+-N与NO_3~--N含量降低,受降水影响轻壤质土壤NH_4~+-N与NO_3~--N更易于向土层深处淋溶,成熟期黏壤质各土层的NH_4~+-N和NO_3~--N含量均多于轻壤质。说明黏壤质土壤保水保氮肥能力强于轻壤质,氮肥基追比可以适当增加。

Effects of the Ratio of Base-topdressing Nitrogen on Wheat Yield, Distribution and Utilization of Water and Nitrogen in Soil

In order to solve the problem of specific application of nitrogen fertilizer varying with the regional soil texture types, the light loam and clay loam were respectively set with no application of nitrogen fertilizer, and the ratios of base-topdressing nitrogen (N) fertilizer at 3:7, 4:6, 5:5, 6:4 and 7:3. The yield, water and nitrogen utilization efficiency in wheat, dynamic changes of soil moisture, water storage, NH₄⁺-N and NO₃^--N contents were studied. The results showed that the highest wheat yield, water use efficiency (WUE) and N production efficiency (NPE) of light loam soil with N base-topdressing ratio at 4:6 were 8 265.3 kg/hm², 27.6 kg/(hm²·mm) and 34.4 kg/kg, respectively. The highest wheat yield, WUE and NPE with N base topdressing ratio of 5:5 in clayey soil were 8 363.2 kg/hm², 28.3 kg/(hm²·mm) and 34.8 kg/kg, respectively. The vertical distribution of soil water content in different growth stages of wheat varied greatly. The water content of light loam soil was 9.3%~26.2%, while 9.7%~27.6% in clay soil. During the whole growth period of wheat, the soil water storage capacity increased at first and then decreased. The water storage capacity of clayey soil was higher than that of light loam. The higher the amount of N topdressing, the higher contents of NH₄⁺-N and NO₃^--N in the surface soil, and the contents of NH₄⁺-N and NO₃^--N decreased with the soil depth. Under precipitation, the contents of NH₄⁺-N and NO₃^--N in light loam soil were easier to leach to the soil depth, and the contents of NH₄⁺-N and NO₃^--N in clay loam soil were higher than those in the light loam at maturity. The results showed that the ability of water and N conservation in clayey soil was stronger than the light loam soil, and the ratio of base-topdressing N could be increased appropriately.