不同强度短期放牧对高寒草甸土壤理化性质的影响

Effects of Short-term Grazing with Different Intensities on Soil Physicochemical Properties in Alpine Meadow

为探索不同强度短期放牧对高寒草甸土壤理化性质的影响,在甘肃省碌曲县加仓村选择禁牧5年的高寒草甸草地作为试验样地,选择体重相近(300 kg,每头按5个羊单位计算)、健康无病的成年牦牛,采用禁牧(G0)、轻度放牧(13个羊单位/hm^(2),G1)、中度放牧(17.5个羊单位/hm^(2),G2)和重度放牧(32.5个羊单位/hm^(2),G3)4种模式放牧120 d。结果表明,放牧均显著降低了草地土壤的有机碳(SOC)和全氮(TN)含量(P<0.05),增加了土壤pH值和土壤硝态氮(NO3--N)含量(P<0.05);随着放牧强度的增加,草地土壤全磷(TP)、铵态氮(NH4+-N)、速效磷(AP)和速效钾(AK)呈先增加后降低趋势,TP、AP和AK含量均在G1放牧时达到最大值,且显著高于其他放牧强度(P<0.05)。综上可以认为,在实际生产中,短期内采用G1放牧强度更适合对草地的可持续利用,且有利于草地土壤发育。

In order to explore the effects of short-term grazing with different intensities on the physicochemical properties of alpine meadow soil,a 5-year grazing-prohibited alpine meadow grassland was selected as an experimental plot in Jiacang village,Luqu county,Gansu province.Healthy and disease-free adult yaks with similar weight(300 kg,calculated at 5 sheep units per yak)were selected as experimental animals.Four grazing modes were used such as prohibition grazing(G0),light grazing(13 sheep units/hm^(2),G1),moderate grazing(17.5 sheep units/hm^(2),G2),and heavy grazing(32.5 sheep units/hm^(2),G3)for 120 days.The results showed that grazing significantly reduced the content of organic carbon(SOC)and total nitrogen(TN)in grassland soil(P<0.05),increased soil pH value and nitrate nitrogen(NO3--N)content(P<0.05);with the increase of grazing intensity,the total phosphorus(TP),ammonia nitrogen(NH4+-N),available phosphorus(AP),and available potassium(AK)in grassland soil showed a trend of first increasing and then decreasing,TP,AP,and AK contents all reached their maximum values under G1 grazing conditions and were significantly higher than other grazing intensities(P<0.05).In summary,it can be concluded that in practical production,adopting G1 grazing intensity in the short term is more suitable for sustainable utilization of grasslands and is beneficial for the development of grassland soil.