稻草覆盖对马铃薯土壤养分释放及养分平衡的影响

【目的】探索马铃薯种植过程中稻草覆盖还田模式下稻草N、P、K释放和土壤N、P、K养分平衡的特征。【方法】采用盆栽试验的方法,对稻草覆盖还田后的腐解速率及养分释放状况进行研究。【结果】稻草覆盖还田82 d后,其C、P含量变化较小,K含量降低93.96%,而N含量却提高了49.22%;覆盖稻草可为土壤提供大量养分且以K居多,每覆盖还田100 kg稻草可为马铃薯生长提供N 0.42 kg、P 0.14 kg(P_2O_5)和K 1.70 kg(K_2O);稻草腐解率为70.87%;各养分累积释放率表现为:KCPN,C、N和P累积释放率分别为71.89%、56.85%和68.75%,K累积释放率最高,为98.22%。覆盖稻草和施用钾肥对土壤K平衡影响较大,不施钾肥和稻草土壤的K亏缺达163.80 kg/hm~2,覆盖稻草或施用钾肥均可有效降低土壤钾素亏缺量,稻草与钾肥配合施用可使土壤K收支平衡,甚至盈余。【结论】在稻草覆盖还田情况下,可适当减少钾肥用量,以降低生产成本,缓解我国钾肥资源匮乏的困境。

Effects of straw mulching on nutrient release and nutrient balance in potato soil

Objective To study the characteristics of nitrogen(N), phosphorus(P) and potassium (K) nutrient release and soil N, P, K nutrient balance under straw mulching pattern during potato planting process.Method We studied the decomposition rate and nutrient release status of mulching straw using pot experiment.Result Straw carbon (C) and P contents changed slightly after mulching for 82 days, while K content decreased by 93.96%, and N content increased by 49.22%. The mulching straw provided a large amount of nutrients (especially K) with 100 kg mulching straw contributing 0.42 kg N, 0.14 kg P (P₂O₅), and 1.70 kg K (K₂O) to soil used for potato growth. Straw decomposition rate was 70.87%. The nutrient accumulative release rates were performed as: K (98.22%) > C (71.89%) > P (68.75%) > N (56.85%). Straw mulching and K fertilization largely affected soil K balance. The K deficient amount was 163.80 kg/hm² without straw mulching and K fertilizer application. K deficient amount was effectively reduced by straw mulching and K fertilization, and even K had surplus with combined application of straw and K fertilizer.Conclusion The straw mulching pattern can reduce K fertilizer application amount and production cost, and relieve the dilemma of K fertilizer resource deficiency in China.