适宜磷、钾肥配比及稻秆半量还田提高紫云英产量与养分截获

Appropriate ratios of phosphate and potassium fertilizers and 50%return of rice straw enhanced yield and nutrient capture of Chinese milk vetch

紫云英为南方稻区最主要的冬季绿肥作物。在紫云英生育期筛选磷、钾肥适宜配比,明确稻秆还田替代钾肥效果,可为福建稻区紫云英高效栽培与水稻化肥减施提供依据。田间条件下,磷肥(P2O5)设0、15、30 kg·hm^(-2)3个水平,钾肥(K2O)设0、15、30 kg·hm^(-2)以及稻秆半量还田替代4个水平,二者完全组合共12个处理,主要测定紫云英盛花期农艺性状、产量、养分含量及截获量。结果表明,与不施磷、钾肥处理(CK)相比,磷、钾肥不同配比的紫云英株高、茎粗、株数、总分枝数最大增幅分别为6.2%、5.9%、8.1%、6.5%,紫云英鲜草产量与干草产量分别增幅1.3%~12.8%与1.4%~15.1%,其中30 kg·hm^(-2)磷肥与15 kg·hm^(-2)钾肥配比,紫云英干草产量最高。30 kg·hm^(-2)磷肥与30 kg·hm^(-2)钾肥配比,氮、磷、钾养分截获总量最高,分别比CK提高19.2%、18.8%、25.9%,差异均显著。稻秆半量还田的紫云英增产与氮、磷、钾养分截获效果与15~30 kg·hm^(-2)钾肥用量基本相当。磷、钾肥配施可改善紫云英生长性状并提高生物量和养分截获量,稻秆半量还田能够替代紫云英生育期钾肥施用量。综合产量、养分截获与化肥减施节本因素,福建稻区紫云英以15 kg·hm^(-2)磷肥配施15 kg·hm^(-2)钾肥(或稻秆半量还田替代钾肥)为较优配比。

Chinese milk vetch(CMV)is the most important winter-grown green manure crop in the southern ricecropping areas of China.This research investigated the appropriate ratio of phosphorus(P)to potassium(K)fertilizer during the cultivation of CMV,and the effect of rice straw(a substitute for K fertilizer)return to provide a basis for recommendations for efficient cultivation of CMV and reduction of chemical fertilizer use in Fujian paddy areas.A total of 12 treatments were established,including three phosphate fertilizer levels:0,15,30 kg·ha^(-1)(P2O5),four potassium fertilizers levels:0,15,30 kg·ha^(-1)(K2O)and 50%of rice straw from the preceding crop returned to the field.The agronomic characteristics,yield,nutrient content and nutrient capture of CMV were determined during the full-bloom period.It was found that,compared with no phosphate and potassium fertilizer(CK),the largest increases in plant height,stem diameter,plant number,and total branch number were obtained with ratios of phosphate:potassium fertilizers of,respectively,6.2%,5.9%,8.1%,6.5%.The yields of fresh and dry CMV(compared to CK)were increased by 1.3%-12.8%and 1.4%-15.1%,respectively,and the highest dry matter yield of CMV occurred in a treatment that combined 30 kg·ha^(-1) P fertilizer and 15 kg·ha^(-1) K fertilizer.Nutrient captures of nitrogen,phosphorus and potassium were highest in a treatment which combined 30 kg·ha^(-1) P and 30 kg·ha^(-1) K fertilizer,and were higher than in the CK treatment by 19.2%,18.8%and 25.9%,respectively(P<0.05 in each case).The yield and nutrient capture of nitrogen,phosphorus and potassium in the treatment with 50%of rice straw returned to field were equivalent to those of the treatments with 15-30 kg·ha^(-1) K fertilizer.In summary,appropriate combinations of P and K fertilizer application improved the growth of CMV,and resulted in higher herbage yield and nutrient capture,than in CK.Moreover,50%return was able to largely substitute application of K fertilizer during the cultivation of CMV.Based on yield,nutrient capture,chemical fertilizer reduction and cost saving,the optimal combination was 15 kg·ha^(-1) P and 15 kg·ha^(-1) K fertilizer(or 50%rice straw return to the field in lieu of K fertilizer).