华北平原有机肥替代化肥条件下“粮-饲”轮作系统氮素表观平衡研究

Apparent nitrogen balance in different crop rotation systems when substituting mineral fertilizers with manure in the North China Plain

为揭示有机肥替代化肥条件下华北平原不同轮作体系土壤-作物系统氮素表观平衡,布置田间试验,定量研究了不同施肥方式[化肥表施(C)、固态粪肥表施替代50%化肥氮(S)、液态粪肥注射施用替代50%化肥氮(L)]和不同轮作方式[籽粒玉米-小麦(T1)、青贮玉米/豇豆间作-填闲黑麦草(T2)、甜高粱-黑麦草(T3)、青贮玉米-黑麦草(T4)、高丹草-黑麦草(T5)]对作物地上部生物量及其氮携出量、0~200 cm土壤剖面硝态氮残留和土壤-作物系统氮表观损失的影响。结果表明:与轮作方式T1相比,T5夏秋季作物地上部生物量及其氮携出量提高幅度最大,其次为T3和T4,而T2却有所降低;各轮作方式冬春季地上部生物量较T1均有所降低,而对其氮携出量无明显影响。与施肥方式C相比,S和L可显著降低夏秋季作物地上部生物量及其氮携出量,降幅均小于15%,而对冬春季作物地上部生物量及其氮携出量无显著影响。与轮作方式T1相比,T3和T5可显著增加周年作物氮总输出量,且显著降低0~200 cm土层无机氮残留量和系统氮表观损失;与施肥方式C相比,S和L可显著降低周年作物氮总输出量和0~200 cm土层无机氮残留量,增加系统氮表观损失。研究表明,在华北平原农牧生产区,以养殖产生的固态和液态粪肥替代50%化肥氮条件下,甜高粱-黑麦草和高丹草-黑麦草轮作是氮肥偏生产力高、表观损失低的轮作方式。

We aimed to the explore the apparent N balance in different forage and crop rotation systems when substituting mineral fertilizer with solid and liquid manure in the North China Plain. To achieve this, we measured the aboveground biomass and N uptake, residual amounts of inorganic N in the 0~200 cm soil profile, and apparent N loss in the soil(0~100 cm)-crop system. Several forage crop rotation systems [grain maize–wheat(T1), silage corn/cowpea intercropping–catch ryegrass(T2), sweet sorghum–ryegrass(T3), silage corn–ryegrass(T4), sorghum hybrid sudangrass–ryegrass(T5)] were studied, substituting 50% of the chemical fertilizer-N(C)with solid manure(S)or liquid manure(L)in the North China Plain. The increases in aboveground biomass and N uptake in the summer-autumn(Sum-Aut)periods were larger under T5, followed by T3, than under T1;however, the highest yields of aboveground biomasses were under T1 in the winter-spring(Win-Spr)periods. Compared with the application of mineral fertilizer NPK(C), the S and L applications significantly reduced the aboveground biomass and N uptake to less than 15% in the Sum-Aut periods but had no significant effects in the Win-Spr periods. Compared with the T1, the T3 and T5 significantly increased crop N harvest and, thus, reduced the residual amounts of inorganic N in the 0~200 cm soil profile and apparent N loss in the soil(0~100 cm)-crop system. Substitution of S and L significantly reduced crop N harvest and residual amounts of inorganic N in the 0~200 cm soil profile, thus, significantly increasing the apparent N loss in the crop–soil system. Therefore, the substitution of 50% of the mineral-N with solid or liquid manure in the agriculture of sweet sorghum–ryegrass and sorghum hybrid sudangrass–ryegrass is conducive to sustainable agriculture and animal husbandry in the North China Plain.