考虑饲草料质量的家庭牧场水土草畜平衡计算方法与应用

家庭牧场作为牧区的基本生产单元，开展家庭牧场水土草畜平衡计算合理确定灌溉人工草地和牲畜饲养规模，对促进水资源可持续利用和维护草地生态安全具有实际管理意义。该研究针对牧区具体管理单元水土草畜平衡计算方法缺乏的问题，同时考虑了不同种类饲草料质量的差别，提出了考虑饲草料质量的家庭牧场水土草畜平衡计算方法，以内蒙古自治区鄂托克前旗典型家庭牧场为例，计算结果表明家庭牧场现状灌溉人工草地和牲畜均处于轻度超载状态，水资源超载率为6.05%，考虑饲草料质量前后牲畜超载率分别为12.98%和5.38%。针对现状平衡状况提出了调整种植结构和灌溉形式组合的8套优化调控方案，经不同方案可供水量变化以及可承载的灌溉人工草地和牲畜饲养规模对比分析，表明种植质量更高的饲草料、采用更节水的灌溉形式可明显提升水资源对灌溉人工草地和饲草资源对牲畜的承载能力，为给家庭牧场水资源和天然草地更多的修养生息空间，建议家庭牧场保持现有人工草地面积不增加，将紫花苜蓿灌溉形式调整为地下滴灌。将燕麦灌溉形式调整为滴灌时，核减牲畜至464羊单位维持家庭牧场水土草畜平衡；将固定式喷灌燕麦调整为滴灌玉米或地下滴灌紫花苜蓿，虽计算的适宜牲畜高于现状牲畜饲养量，但仍保持现有牲畜饲养规模。提出的计算方法可为牧区水土草畜平衡计算与管理提供一种新的思路。

Calculation method and application of the tradeoff on water, land, forage, and livestock in family pasture considering forage quality

Abstract: Most pastoral areas in China are subjected to arid and semi-arid zones, particularly with annual precipitation of less than 400 mm. Since irrigation is indispensable for the cultivated grass industry, the protection of natural grassland can focus on the water, land, forage, and livestock balance with the development of the irrigation cultivated grasslands, rather than the forage-livestock balance only. Taking the specific pastoral management units as the entry point, this study aims to propose a new evaluation for the tradeoff between the water and land for the family pasture from the perspective of the water cycle. A water-land-forage-livestock balance was constructed to consider the quality differences between forage species in the calculation of the forage-livestock balance. An example was taken as the typical family pasture in the Otog Front Banner of the Inner Mongolia Autonomous Region in China. The assessment showed that the current water, land, forage, and livestock status of the family pasture were in a mild overload state, with a water resource overload rate of 6.05%. In the condition of water, land, forage, and livestock balance, the livestock overload rates with/without considering forage quality were 5.38% and 12.98%, respectively. By contrast, the livestock overload rates with/without considering forage quality were 1.29%, and 9.05%, respectively, under current planting conditions (without considering water resource overload). An optimal combination of water-use schemes was proposed to feature the different planting structures and irrigation adjustments, according to the status quo in this family pasture. A systematic analysis was made to determine the available water supply, and the carrying capacity for the irrigation of cultivated grasslands, and livestock under multiple optimizations. It was found that the carrying capacity was determined for the irrigation of cultivated grasslands by the available water supply. More water-efficient irrigation was adopted to select the forage crops with the decreased water consumption, in order to significantly improve the support capacity of water resources in the irrigation-cultivated grasslands. Livestock carrying capacity significantly increased after considering the forage quality, indicating more consistency with the actual condition of this family pasture. Consequently, the family pasture was maintained the current areas of cultivated grassland without increasing, while adjusting the irrigation of alfalfa to underground drip irrigation. Once the irrigation form was adjusted to drip irrigation under the condition of oat planting, the number of livestock was reduced to 464 sheep units, in order to maintain the balance of water, land, forage, and livestock in the family pasture. Furthermore, the oats were adjusted to grow the corn or alfalfa in the median condition of oats. Although the number of livestock was more than the current number of livestock, some suggestions can keep the current number of livestock raised in family pastures, in order to make more room for the rest and recuperation of water resources and natural grassland. The finding can provide a new approach to calculating and managing the water, land, forage, and livestock balance in pastoral areas.