有机肥和化肥长期配合施用对土壤及不同粒级供氮特性的影响

通过间隙淋洗培养试验 ,研究水旱轮作下有机肥与化肥长期配合施用后土壤及不同粒级中氮的矿化特性。结果表明 ,经 14年 2 9茬连续施肥后土壤氮素矿化势明显增加 ,不同处理间的顺序为 :猪粪 化肥 (3 10mgkg- 1) >秸秆 化肥 (2 98mgkg- 1) >化肥 (2 76mgkg- 1) >对照 (2 0 4mgkg- 1)。长期施肥对土壤氮素矿化速率常数影响较小 ,反映了在相同土壤条件下有机氮矿化的共性。经 16周连续培养各处理土壤氮素的矿化率均在 17%左右。土壤不同粒级中氮的矿化量和矿化势均为 0～ 2 μm >2～ 10 μm >50～ 10 0 μm >10～ 50 μm ,有机肥与化肥长期配合施用显著增加了 0～ 2和 2～ 10 μm粒级氮的矿化势和矿化量。与盆栽试验结果相比 ,培养过程矿化释放的氮明显高于同期土壤的供氮量 ,表明在使用矿化氮评价土壤供氮能力时必须加以矫正。

INFLUENCE OF LONG-TERM COMBINED APPLICATION OF MANURE AND CHEMICAL FERT ILIZER ON SUPPLYING CHARACTERISTICS OF NITROGEN IN SOIL AND SOIL PARTICLE FRACTIONS

Nitrogen mineralization of soil and soil particle fractions with long-term annual combined application of manure and chemical fertilizer in a wheat/rice rotation system was monitored during a 112-day laboratory incubation NH₄⁺ and NO₃^-in leachates were measured after soil samples were incubated for 1,2,4,6,8,10,12,14 and 16 weeks at 25 Nitrogen mineralization potential(N₀)and mineralized rate constant(k)were fitted using a first order equation N₀ value of soil and soil particle fractions was significantly increased after 14-year incorporation of pig manure and straw,however,there was no significant effect on k value The N mineralizability in different soil particle fractions increased in the order:0~2 m>2~10 m>50~100 m>10~50 m A pot experiment was also conducted to determine the basic nitrogen supply of the soil and soil particle fractions during 16-week growth of ryegrass The results showed that the amount of N mineralized during the incubation was greater than those taken up by ryegrass,suggesting that it is worthwhile making some modifications when we make comparison of the results obtained from incubation and pot experiments.