| The intensive livestock production is developing very fast in China.Dairy farming has gone through the transformation from family feeding,collected feeding to intensive feeding.And the sustainable livestock production has been becoming a hot issue,regarding how to optimize the regional distribution of animal farms,how to reduce the environmental risk associated with manure and how to supply the feed with high quality.To better understand the limited factors in current livestock production and explore the extension potential of integrated livestock-crop system,we conducted case study in Luannan County.Here we established systematical quantitative indexes,including feed nutrient use efficiency,manure collecting rate,manure field returning rate,local self-sufficient rate of feed and village-level nutrient balance to illustrate the influence of diary production transformation.We focused on livestock scale,the level of combination of animal feeding and technologies on nutrient use efficiency in each process combined with farm survey study in different develop stage.We have found the main results as follows:(1)There were various manure treatments in current scattered farming system and the ratios of manure recycling to cropland have exceeded 50%in Luannan smallholder farms.However,the courtyard sanitation is poor caused by the manure storage,and the animal production efficiency is low(i.e.milk yield 16.0 kg head-1 d-1,)as well as low nitrogen use efficiency(17.1%).Among manure treatments,the biogas turned to be a clean technology with high nutrient use efficiency and low environmental risk while its performance on improving manure collecting rate and reducing courtyard pollution changed greatly in different regions.For example,only 5%manure could be used for biogas with increasing of 2669 kg CO2-eq GHG emission in Northern China,and the biogas farmers also have decreased by 73.1%in Luannan.In contrast,above 90%manure could be used as biogas with an CO2-eq GHG emission reduction of 6336 kg in Southern China,and the biogas farmers have increased 6.7%(We have conducted a supplementary famer survey in Sichuan province).The environmental mismatching,unfit volume combination of manure and biogas,imbalance of household energy demand and biogas supply,too high public service cost of biogas producing too low benefits,and nutrient from biogas being unsuitable for crop demand altogether contributed the low use efficiency and high emission of biogas technology in Northern China.(2)The conversion from family feeding to intensive feeding increased the milk yield from 20.3 to 30.1 kg head-1 d-1,and enhanced the feed nitrogen use efficiency from 18.0%to 20.1%from 4 village case study.However,nitrogen use efficiency of the integrated system significantly decreased from 39.4%to 27.4%resulted from the decrease of manure recycling rate from 74.4%to 43.2%.This is mainly due to high price of manure(30 Yuan Mg-1)and the surrounding farmers could not afford it who grows wheat,corn,peanut and other traditional crops.On the other hand,94.5%of feed are alfalfa,guinea grass,maize silage and other high-quality forage while the surrounding small farmers could not meet this demand and the conversion rate of straw residue and seed to feed decreased from 44.1%to 1.7%.(3)Some intensive dairy farms expanded arable land for feed production and manure recycling and achieved the integrated livestock-crop production partly.Comparing with the intensive dairy farms without arable land,the farms with arable land improved the milk yield by 18%and 25%at lactating cow and herd level respectively from case study of 3 integrated farms and 5 livestock only farms.The difference may because farms from integrated system used high quality feed produced in their own land(68%maize silage from their own land).They(Dairy farms with land)also improved manure recycling rate by 18.7%(10.2%higher than that without land)for the utilization of the adoption of the manure cleaning machinery,and consumed 38%of own manure.Moreover,the manure use and planting structure have not match well in current integrated farms with key limited factor of land deficiency.And the smallholders did not changed their practice of manure management or planting structure to meet the goal of synergetic improvement regionally.(4)The contradiction between the crop planting and animal feeding is both from the limit of the land and production technology.One hand,we need to improve the planting efficiency and manure returning rate in animal farm with cropland,and on the other hand,achieving transformation of planting pattern and nutrient use in surrounding farms by combining livestock farms with small growers are critical for solving the problems.Our field experiment(on grass substituting crop model and manure fertilization technology)indicated that manure nitrogen(with 180 kg ha-1,)with optimized irrigation(262 mm ha-1)can improve alfalfa yield and lower nitrate leaching risk.The optimized nutrient management technology has great potential in addressing the contradiction between the crop production and animal feeding. |
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