施氮和刈割对辽西北退化草地牧草产量和品质的影响

Effects of nitrogen application and mowing on yield and quality of forage in degraded grassland in northwest Liaoning Province

施氮和刈割是天然草地有效管理方式。为探究退化草地高效利用方式,以辽宁省西北部农牧交错区退化草地为研究对象,设置氮肥添加(0、10 g N·m^(-2)·a^(-1))和刈割处理(留茬高度3、6、12 cm、不刈割),通过连续两年测定牧草产量和22项牧草品质指标,分析施氮和刈割对辽西北退化草地牧草产量和品质的影响。结果表明:1)施氮显著提高了2018和2019年产草量、粗蛋白和2019年牧草产奶净能、维持净能、增重净能、总可消化养分、奶吨指数,极显著降低了2019年酸性洗涤纤维含量,对退化草地牧草产量、净能以及养分含量的提升均有促进作用。2)刈割显著影响了2018和2019年牧草中性洗涤纤维、钙元素、磷元素含量、体外干物质消化率和相对饲喂价值,2018年粗灰分、镁元素含量以及2019年非纤维性碳水化合物、维持净能、增重净能、总可消化养分和相对饲草品质,在对退化草地进行适度利用的同时牧草品质也有较大提升。3)施氮和刈割交互作用对退化草地牧草粗蛋白、粗灰分、产奶净能以及奶吨指数有显著影响。4)牧草粗灰分、酸性洗涤纤维、中性洗涤纤维、可消化中性洗涤纤维、中性洗涤纤维消化率、镁元素、产奶净能、维持净能、增重净能、奶吨指数、总可消化养分以及相对饲喂价值共12项营养品质指标与粗蛋白之间存在显著相关关系。研究表明,施氮和刈割作为退化草地的有效管理和利用方式,单独作用或交互作用均对牧草产量和品质的提升有不同程度的正向反馈,其中以施氮结合留茬3 cm刈割处理下牧草产量和品质最高,可为退化草地的合理利用和可持续发展提供理论参考。

Nitrogen application and mowing treatment are effective management methods for natural grassland. In order to explore the efficient use of degraded grassland,the degraded grassland in the pastoral transitional zone of northwestern Liaoning Province was taken as the research object,and nitrogen fertilizer addition(0,10 g N·m-2·yr-1)and mowing treatment(stubble height at 3,6,12 cm and no mowing)experiment were set up,by measuring forage yield and 22 forage quality indicators for two consecutive years,to analyze the effects of nitrogen application and mowing on the yield and quality of degraded grasslands in northwestern Liaoning Province. The results showed that:1)Nitrogen application significantly increased the forage yield,crude protein in 2018 and 2019,and the forage net energy for lactation,net energy for maintenance,net energy for gain,total digestible nutrients,MT(kg milk·t-1 DM)in 2019,nitrogen application significantly reduced the acid detergent fiber in 2019,and promoted the increase of forage yield,net energy and nutrient content in degraded grassland. 2)Mowing treatment significantly affected the forage neutral detergent fiber,calcium content,phosphorus content,in vitro dry-matter digestibility and relative feeding value in 2018 and 2019,and the forage crude ash and magnesium content in 2018,and the forage non-fibrous carbohydrate,net energy for maintenance,net energy for gain,total digestible nutrients and relative forage quality in2019,while the degraded grassland was properly utilized,the quality of forage grass also improved greatly. 3)The interaction of nitrogen application and mowing treatment had a significant impact on the crude protein,crude ash,net energy for lactation and MT of degraded grassland. 4)The forage crude ash,acid detergent fiber,neutral detergent fiber,digestible neutral detergent fiber,neutral detergent fiber digestibility,magnesium content,net energy for lactation,net energy for maintenance,net energy for gain,MT,total digestible nutrients as well as the relative feeding value,a total of 12 nutritional quality index were significant correlated with crude protein. The results showed that nitrogen application and mowing treatment as effective management and utilization way of degraded grassland,both the independent or interactive effects had different degrees of positive feedback on the improvement of forage yield and quality,the yield and quality of forage grass were the highest under the treatment of nitrogen application combined with mowing of stubble height at 3 cm,which could provide a theoretical reference for the rational use and sustainable development of degraded grassland.