Modelling of production systems for estimating dairy and beef cattle production based on floar of solar and fuel energy.

比较了几种不同类型的作物和放牧的太阳能固定效率和生物质生产的能量输出与燃料使用的辅助能量输入的比率。在农民管理和低施肥条件下，动物可利用牧草生物量产量（可利用牧草）为1400 ~ 6700公斤/公顷/年。这些值相当于每年输入的太阳能转化为可供放牧的牧草固定能量的0.20%。牛平均日增重0.5 kg/头/天。将日增益换算成单位面积放牧牧场的能量产出，就可以计算出养牛对太阳能总投入的效率。效率值平均仅为0.0029%。放牧草地的太阳能固定效率较低，但能量输出与燃料能量输入的比值较高。管理良好的牧场在不降低太阳能固定效率的情况下，生物质能源产量与农场燃料能源投入的比率很高。在农场投入1 KJ的燃料能产生0.5 KJ的稻米，2.5 KJ的玉米和燕麦等污染作物青贮，6.2-8.6 KJ的放牧牧场。

Efficiencies of solar energy fixation and the ratios of energy output by biomass production to subsidiary energy input by fuel use were compared among several types of cropping and grazed oasture.The biomass yield of herbage available for animals (herbage available) is ranging from 1400 to 6700 kg/ha/year under the conditions of farmer's management with low level of fertilizer application. These values correspond to 0.20 % of the conversion efficiency from the annual solar energy input to the fixed energy of the herbage available for grazing cattle.The cattle grew at the rate of 0.5 kg/head/day in body weight gain (daily gain) on an average. Converting the daily gain into the energy yield per unit area of the grazed pasture, we can calculate the efficiency of cattle production to the total input of solar energy. The value of efficiency was only 0.0029 % on an average.Grazed pasture showed lower efficiencies of solar energy fixation, but higher ratios of energy output to fuel energy input. Well managed grazing pasture gave a high value of the ratio of biomass energy yield against on-the-farm fuel energy input without reducing the efficiency of solar energy fixation. Input of 1 KJ of fuel energy on-the-farm produced 0.5 KJ in rice grain, 2.5 KJ in silage of soiling crops such as corn and oat and 6.2-8.6 KJ in grazed pasture.