玉米秸秆全量还田条件下氮肥运筹对晚稻产量和土壤化学及微生物特性的影响

Effects of Nitrogen Application on Yield of Late Rice, Soil Chemical and Microbial Characteristics under the Condition of Full Corn Straw Returning

以桃优香占为材料,在前茬玉米秸秆全量还田条件下,研究了4种氮素运筹方式(NM1,基肥∶蘖肥∶穗粒肥分别为7∶3∶0;NM2,6∶3∶1;NM3,5∶3∶2;NM4,4∶3∶3)对晚稻产量及形成、土壤化学及生物特性的影响。结果表明,NM1处理产量最高,分别较NM2、NM3、NM4处理高2.6%、5.3%、5.6%,差异显著,其次为NM2处理。玉米秸秆全量还田配合氮素前移可以显著提高水稻单位面积有效穗数,显著降低每穗粒数和结实率,但对千粒重无显著影响。氮素运筹方式对土壤理化特性影响主要集中在秸秆还田后至分蘖期,且土壤碱解氮、有机质含量和脲酶活性随着基蘖肥比例的增加而增大。水稻土壤中细菌、真菌、放线菌、固氮菌和硝化细菌量在前茬玉米收获后最高,且随着水稻生育时期的推进迅速降低。土壤细菌、放线菌、氨化细菌和硝化细菌在分蘖期随基蘖肥比例的提高而增加,而在抽穗期大致随基蘖肥比例的提高而减少,成熟期各处理无显著差异;氮素运筹方式对土壤真菌、固氮菌在水稻各生育时期均无显著影响。玉米秸秆全量还田有利于提高后茬水稻生育前期土壤肥力和微生物活性,以基肥∶蘖肥∶穗粒肥分别为7∶3∶0的氮素运筹方式晚稻产量最高,土壤改良效果最好,实现了后茬水稻稳产甚至增产。

The effects of four nitrogen application modes (NM1, basal fertilizer: tillering fertilizer∶ear and panicle fertilizer were 7∶3∶0;NM2, 6∶3∶1;NM3, 5∶3∶2;NM4, 4∶3∶3) on yield of late rice and its formation, paddy soil chemical and biological characteristics were studied with Taoyouxiangzhan as material by field trail in 2017. The results showed that, NM1 treatment obtained the highest yield, and that was 2.6%, 5.3% and 5.6% significantly higher than treatments NM2, NM3 and NM4, respectively. Treatment NM2 had the second high yield. Advanced nitrogen application under the condition of the full amount of previous corn straw returning significantly increased the effective panicles per unit area and decreased the grains per spike and seed setting rate, but had no significantly effect on thousand grain weight. The effects of different nitrogen application modes on paddy soil physicochemical characteristics were concentrated on the corn straw after returning to tillering period. In this period, soil alkali hydrolysable nitrogen, organic matter content and urease activity increased with the increase of the proportion of basal and tillering fertilizer. The bacteria, fungi, actinomycetes, azotobacter and nitrifying bacteria biomass in paddy soil were the highest after corn harvest, and decreased rapidly with the growth of late rice. The bacteria, actinomycetes, ammoniated bacteria and nitrifying bacteria biomass in paddy soil significantly increased with the increase of the proportion of basal and tillering fertilizer, but roughly decreased in heading stage and had no significant difference between all treatments in maturity. Nitrogen application modes had no significantly effect on fungi and azotobacter biomass in paddy soil in any stages of rice. The full amount of previous corn straw returning was favorable for improving the soil fertility and microbial activity in early stage of rice. The highest yield and the best paddy soil improvement had obtained when the nitrogen application modes of basal fertilizer∶tillering fertilizer∶ear and panicle fertilizer was 7∶3∶0.