秸秆和地膜覆盖对渭北旱作玉米农田土壤氮组分与产量的影响

Effects of straw and plastic film mulching on soil nitrogen fractions and corn yield in the Weibei rainfed highland

基于田间定位试验,研究了秸秆和地膜覆盖措施对旱作春玉米田土壤氮组分和作物产量的影响。试验包括无覆盖对照,秸秆覆盖和地膜覆盖3个处理,观测指标包括土壤全氮(STN)、颗粒有机氮(PON)、潜在可矿化氮(PNM)、微生物量氮(MBN)、硝态氮(NO_3^--N)、铵态氮(NH_4^+-N)含量及作物产量。结果表明:试验进行5到7年后,与对照相比,秸秆覆盖处理0—10 cm土层STN、PON、PNM、MBN和NO_3^--N含量3年平均分别提高了13.11%、64.29%、17.51%、16.94%和55.37%,10—20 cm土层STN、PON、MBN和NO_3^--N含量3年平均分别提高了5.93%、33.33%、15.78%和27.57%(P<0.05)。而地膜覆盖处理0—10 cm和10—20 cm土层NO_3^--N的含量较对照分别提高了189.14%和135.75%(P<0.05),其他氮组分与对照处理差异不显著。秸秆和地膜覆盖处理玉米产量较对照处理3年平均分别提高了6.90%和36.74%(P<0.05)。玉米产量与0—20 cm土层NO_3^--N含量和NO_3^--N/STN值呈显著正相关关系。总的来看,秸秆覆盖能显著增加旱地土壤全氮和活性有机氮含量,促进氮素固定,但需注意作物生长后期补充氮肥以满足作物生长需要。而地膜覆盖能显著提高土壤氮素有效性和作物产量,但不利于土壤有机氮的固定,且表层土壤存在潜在氮淋失风险。

Mulching with straw and plastic film has been widely used to conserve soil water, increase temperatures, and increase crop yield in the dryland areas. However, its influence on soil nitrogen fractions is not well known. Based on a 7 year field experiment in the Weibei rainfed highland area of Loess Plateau of China, we compared the long-term effects of straw and plastic mulching on soil total nitrogen （STN）, particulate organic nitrogen （PON）, potential nitrogen mineralization （PNM） , microbial biomass nitrogen （MBN） , and mineral nitrogen （NO3 --N and NH4＋ -N） as well as on corn yield. Three treatments were included： no mulching, straw mulching, and plastic film mulching. Averaged across 5--7 years, the concentrations of STN, PON, PNM, MBN, and NO3 --N at 0--10 cm depth increased by 13.11%, 64.29%, 17.51%, 16.94%, and 55.37%, and the STN, PON, MBN, and NO3- -N concentrations at 10--20 cm increased by 5. 93%, 33.33%, 15.78%, and 27.57% with straw than with no mulching （P〈0.05）, respectively. The concentration of NO3--N increased by 189.14% and 135.75% at 0-10 and 10-20 cm in plastic film compared to no mulching （P〈0.05） , respectively, and no significant differences in other fractions were found between plastic film and no mulching at both soil depths. Crop yield was improved by 6.90% and 36.74% in straw and plastic film mulching compared with no mulching （P〈 0.05） , respectively. Corn yield positively correlated with NO3-N and NO3-N/STN contents at 0-20 cm depths. Overall, straw mulching is favorable on soil N sequestration and could increase soil N activity and crop yield. However, N fertilizer should be applied during the late growing stage to maintain corn yield. Plastic mulching can effectively increase crop yield, but had no effect on soil total nitrogen, and its fractions and increased the risk of N leaching due to high NO3- -N accumulation in the soil.