苏丹草-黑麦草轮作制中施肥对饲料产量、养分吸收与土壤性质的影响

大田试验条件下采用苏丹草(Sorghum sudanense)与黑麦草(Lolium L.)轮作，分别设CK(不施肥)、NP(施氮磷肥)、NK(施氮钾肥)、PK(施磷钾肥)、NPK(施氮磷钾肥) 5个处理研究施肥对饲草产量、养分吸收及土壤养分的影响。结果表明，氮磷钾肥配施显著提高苏丹草与黑麦草鲜草产量，2005—2006年与2006—2007年两季饲草分别为162.7 t hm^-2、114.9 t hm^-2，分别比同期PK、NK、NP处理增产312.9%、26.9%、17.9%和338.5%、20.3%、17.2%。施肥影响饲草的氮、磷、钾含量，且氮磷钾配施可以改善饲草养分吸收，2005—2006年NPK处理的饲草N、P、K吸收量分别为500 kg hm^-2、91 kg hm^-2和997 kg hm^-2，2006—2007年NPK处理的饲草N、P、K吸收量分别为312 kg hm^-2、56 kg hm^-2和402 kg hm^-2。轮作系统中，氮磷钾肥配施条件下氮、磷盈余最少，而钾亏缺。在苏丹草-黑麦草轮作制中，随着种植次数的增多，各施肥处理土壤有机质、全氮均有不同程度上升，施磷(NPK、NP、PK)处理的速效磷、施钾(NPK、NK、PK)处理的速效钾均有上升，而NK处理的速效磷、NP处理的速效钾略有下降。

Effect of Fertilization on Yield of Forage Grass,Nutrient Uptake and Soil Properties under Sudangrass and Ryegrass Rotation Regime

Sudangrass and ryegrass rotation is a new type of growth system in Jianghan Plain, which had developed very fast in recent years. So it is highly essential to propose an optimum nutrient management practice for increasing forage grass yield, improving soil fertilization and assuring sustainable development in this new system. Effect of fertilization on yield of forage grass, nutrient uptake and nutrition in soil under Sudangrass and ryegrass rotation regime was studied for two years through the field experiments in Honghu City of Jianghan Plain. The results showed that the application of nitrogen (N), phosphorus (P) and potassium (K) combination obviously improved fresh yield of Sudangrass and ryegrass, with a total forage yield of 162.7 t ha^-1 in 2005–2006, which was 312.9%, 26.9%, 17.9% higher than that of PK, NK, NP treatments, respectively. The total forage yield was 114.9 t ha^-1 in 2006–2007, and 338.5%, 20.3%, 17.2% higher than that of PK, NK, NP treatments, respectively. Fertilization affected nutrient content of forage grass, and N fertilizer increased N content of grass, and K fertilizer increased K content of grass. NPK combination also promoted nutrient uptake of forage grass, with the higher nutrient uptake than other treatments. The total N, P, K uptake of forage grass was 500 kg ha^-1, 91 kg ha^-1and 997 kg ha^-1 in 2005–2006, and 312 kg ha^-1, 56 kg ha^-1, 402 kg ha^-1 in 2006–2007, respectively. In this rotation, the surplus of N and P₂O₅ in NPK treatment was the least, compared with that in NP, NK and PK treatments. However, K₂O surplus in NPK treatment was the negative. In Sudangrass and ryegrass rotation, organic matter and total nitrogen in soil in all treatments, available phosphorus in soil in NPK, NP and PK treatments and available potassium in soil in NPK, NK and PK treatments increased with crop rotation times. But available phosphorus in soil in NK treatment and available potassium in soil in NP treatment slightly degraded, respectively.