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一般来说,土壤中可利用氮的含量总是不能满足禾本科牧草高产的需要,因此,氮的供给往往是饲草生产的主要限制因子。即使土壤中有机态氮的含量较高或很高,也往往在微生物分解和矿化作用的限制下,使禾本科牧草对可利用氮仍感不足。根据乐炎舟等同志研究,对0—20厘米土层中含有机质7%以上,全氮0.4%左右的高山草甸草场施氮时仍有明显的增产效果,平均每斤氮素可增产干草12.9—14.8公斤[2]。国外大量研究表明,施氮不但
In general, the availability of nitrogen in soils does not always meet the need for high yields of grassy pastures and, therefore, the supply of nitrogen is often a major limiting factor in forage production. Even though the content of organic nitrogen in the soil is high or high, grass grasses often remain deficient in available nitrogen under the constraints of microbial decomposition and mineralization. According to the study of Le Yanzhou and other comrades, there is still obvious stimulation effect on alpine meadow pastures containing 0% or more of organic matter in 0-20 cm soil layers and 0.4% of total nitrogen, and the average yield per kilogram of nitrogen can increase the yield of hay 12.9-14.8 kg [2]. A large number of foreign studies show that nitrogen is not only applied