Newton G L, Bernard J K, Hubbard R K, Allison J R, Lowrance R R, Gascho G J, Gates R N, Vellidis G
Department of Animal & Dairy Science, University of Georgia, Tifton 31793, USA.
J Dairy Sci. 2003 Jun;86(6):2243-52. doi: 10.3168/jds.S0022-0302(03)73815-6.
Concentrated sources of dairy manure represent significant water pollution potential. The southern United States may be more vulnerable to water quality problems than some other regions because of climate, typical farm size, and cropping practices. Dairy manure can be an effective source of plant nutrients and large quantities of nutrients can be recycled through forage production, especially when multi-cropping systems are utilized. Linking forage production with manure utilization is an environmentally sound approach for addressing both of these problems. Review of two triple-crop systems revealed greater N and P recoveries for a corn silage-bermudagrass hay-rye haylage system, whereas forage yields and quality were greater for a corn silage-corn silage-rye haylage system, when manure was applied at rates to supply N. Nutrient uptake was lower than application during the autumn-winter period, and bermudagrass utilized more of the remaining excess than a second crop of corn silage. Economic comparison of these systems suggests that the added value of the two corn silage crop system was not enough to off-set its increased production cost. Therefore, the system that included bermudagrass demonstrated both environmental and economic advantages. Review of the N and P uptake and calculated crop value of various single, double, and triple crop forage systems indicated that the per hectare economic value as well as the N and P uptakes tended to follow DM yields, and grasses tended to out-perform broadleaf forages. Taken across all systems, systems that included bermudagrass tended to have some of the highest economic values and uptakes of N and P. Manure applied at rates to supply N results in application of excess P, and production will not supply adequate quantities of forage to meet the herd's needs. Systems that lower manure application and supply supplemental N to produce all necessary forage under manure application will likely be less economically attractive due to additional costs of moving manure further and, applying it to greater land areas, but will be environmentally necessary in most cases. Intensive forage systems can produce acceptable to high quality forage, protect the environment, and be economically attractive. The optimal manure-forage system will depend on the farm characteristics and specific local conditions. Buffers and nutrient sinks can protect streams and water bodies from migrating nutrients and should be included as a part of crop production systems.
集中的奶牛粪便源具有显著的水污染潜力。由于气候、典型农场规模和种植方式等因素，美国南部可能比其他一些地区更容易受到水质问题的影响。奶牛粪便可以是植物养分的有效来源，大量养分可以通过饲料生产循环利用，特别是在采用多熟制系统时。将饲料生产与粪便利用联系起来是解决这两个问题的一种环境友好型方法。对两种三熟制系统的评估表明，在以供应氮的速率施用粪便时，玉米青贮 - 百慕大干草 - 黑麦青贮系统的氮和磷回收率更高，而玉米青贮 - 玉米青贮 - 黑麦青贮系统的饲料产量和质量更高。在秋冬季节，养分吸收低于施用率，百慕大草比第二季玉米青贮利用了更多剩余的过量养分。这些系统的经济比较表明，两季玉米青贮作物系统的附加值不足以抵消其增加的生产成本。因此，包含百慕大草的系统在环境和经济方面都具有优势。对各种单作、双作和三作饲料系统的氮和磷吸收以及计算出的作物价值的评估表明，每公顷的经济价值以及氮和磷的吸收量往往与干物质产量相关，并且禾本科牧草往往比阔叶饲料表现更好。在所有系统中，包含百慕大草的系统往往具有一些最高的经济价值以及氮和磷的吸收量。以供应氮的速率施用粪便会导致过量磷的施用，并且生产出的饲料量将不足以满足畜群的需求。降低粪便施用量并在施用粪便的情况下供应补充氮以生产所有必需饲料的系统，由于进一步运输粪便并将其施用于更大面积土地的额外成本，在经济上可能吸引力较小，但在大多数情况下在环境方面是必要的。集约化饲料系统可以生产出可接受的至高质量的饲料，保护环境，并具有经济吸引力。最佳的粪便 - 饲料系统将取决于农场特征和当地具体条件。缓冲带和养分汇可以保护溪流和水体免受迁移养分的影响，应作为作物生产系统的一部分加以纳入。
