稻-麦轮作条件下不同施肥模式土壤水溶性氮的变化与籽粒产量的关系

Variety of soil water-soluble nitrogen as affected by different fertilization and its relation to grain yields with a rice-wheat rotation

肥料用量、肥料种类和施肥方式直接影响土壤供氮强度和作物的正常生长发育。通过田间试验,研究减量施用氮、磷肥,增加钾肥投入时土壤水溶性氮含量的变化与水稻、小麦籽粒产量的关系。试验设置5个处理:不施肥(CK)、习惯施肥(FP)、推荐施肥(LRF)、商品有机肥部分替代化肥(RF-OM)、秸秆部分替代化肥(RF-S),各处理重复4次。结果表明,水稻幼穗分化期有机肥部分替代化肥处理(RF-OM和RF-S)土壤水溶性总氮、硝态氮含量显著高于LRF处理(P<0.05),与FP处理相当;返青期土壤水溶性总氮、硝态氮、铵态氮含量稍低于FP和LRF处理,差异不显著。小麦拔节期和齐穗期有机肥部分替代化肥处理土壤水溶性总氮、硝态氮含量显著高于LRF处理(P<0.05),小麦主要生育期各施肥处理土壤水溶性铵态氮含量均无显著差异。在减氮减磷增钾条件下,RF-OM处理水稻籽粒产量显著高于LRF处理(P<0.05),有机肥部分替代化肥处理水稻籽粒产量与FP处理差异不大;与LRF处理比较,RF-OM处理小麦籽粒产量较高,RF-S处理小麦籽粒产量有所降低,但差异均未达到显著水平。水稻籽粒产量与返青期土壤水溶性总氮、铵态氮含量均呈极显著正相关(P<0.01),相关系数分别为0.932和0.974;与幼穗分化期土壤水溶性总氮、铵态氮和硝态氮含量也均呈极显著正相关(P<0.01),相关系数分别为0.888、0.961、0.776。小麦籽粒产量与主要生育期土壤水溶性总氮、铵态氮、硝态氮浓度均呈极显著正相关(P<0.01),相关系数分别为0.928~0.960、0.827~0.968、0.574~0.929,土壤水溶性总氮供应对水稻、小麦籽粒产量的影响尤其值得关注。有机肥部分替代化肥能保持或提高土壤水溶性氮含量,在减少养分总投入量的基础上稳定水稻、小麦籽粒产量,其中商品有机肥部分替代化肥模式的效果更佳。

Fertilization including fertilizer type,amount and applying manner directly affects the intensity of soil nitrogen supply and crop growth.A field experiment was conducted to study the effects of different fertilizations on the varieties of soil water-soluble nitrogen and their relation to crop grain yields with a rice-wheat rotation.There were five treatments,including non-fertilization(CK),farmer practice(FP),local recommended fertilization(LRF),commercial organic manure partially replaced chemical fertilizer(RF-OM),straw partially replaced chemical fertilizer(RF-S),and each treatment had four replications.The results indicated that the contents of soil watersoluble total nitrogen and nitrate nitrogen of RF-OM and RF-S treatments were significantly higher than those of LRF treatment at the young panicle differentiation stage of rice(P<0.05),and similar to those of FP treatment.At the returning green stage of rice,the contents of soil water-soluble nitrogen(total nitrogen,ammonium nitrogen and nitrate nitrogen)of RF-OM and RF-S treatments were slightly lower than those of LRF or FP treatment,and the differences were not significant.At the jointing stage or full heading stage of wheat,the contents of soil water-soluble total nitrogen and nitrate nitrogen of RF-OM and RF-S treatments were significantly higher than those of LRF treatment(P<0.05).The differences of soil ammonium nitrogen content among four fertilization treatments at each main growth stage of wheat were not significant.Based on reducing nitrogen and phosphorus doses as well as increasing potassium doses,rice grain yields of RF-OM treatment were significantly higher than those of LRF treatment(P<0.05),and rice grain yields of RF-OM and RF-S treatments were similar to that of FP treatment.Compared with LRF treatment,wheat grain yields of RF-OM treatment were higher,which were reduced of RF-S treatment but the difference did not reach a significant level.It was also found that the rice grain yields were positively significantly correlated to the contents of soil water-soluble total nitrogen and ammonium nitrogen at the returning green stage of rice(P<0.01),with the correlation coefficients of 0.932 and 0.974 respectively.And so were to the contents of water-soluble nitrogen(total nitrogen,ammonium nitrogen and nitrate nitrogen)at young panicle differentiation stage of rice,and the correlation coefficients were 0.888,0.961 and 0.776.The wheat grain yields were positively significantly correlated to the content of soil water-soluble nitrogen(total nitrogen,ammonium nitrogen and nitrate nitrogen)at each main growth stage of wheat(P<0.01),and the correlation coefficients were 0.928~0.960,0.827~0.968 and 0.574~0.929.It is particularly notable that the supply of soil water-soluble total nitrogen is much contributive to rice or wheat grain yields.Organic manure applied as a partial substitute for chemical fertilizers,especially the commercial organic manure partially replaced chemical fertilizers could maintain or increase the content of soil water-soluble nitrogen,as well as stabilize rice and wheat grain yields on the basis of reducing total nutrient inputs.