Department of Animal Sciences, The Pennsylvania State University, University Park 16802.
Department of Animal Sciences, The Pennsylvania State University, University Park 16802.
J Dairy Sci. 2020 Apr;103(4):3804-3815. doi: 10.3168/jds.2019-17525. Epub 2020 Feb 7.
Dairy farms have been under pressure to reduce negative environmental impacts while remaining profitable during times with volatile milk and commodity prices. Double cropping has been promoted to reduce negative environmental impacts and increase total dry matter yield per hectare. Three dairy farms that double cropped winter annuals and corn were selected from northern and western Pennsylvania. Data were collected from recorded crop and dairy records and financial data for 2016 and 2017. Farms ranged in size from 336 to 511 ha with 233 to 663 cows. Data were used to set parameters for the Integrated Farm System Model, which was then used to simulate 8 scenarios for each farm: current operation; 0, 50, and 100% of corn hectares double cropped; 30% feed price increase with and without double cropping; and 30% feed price decrease with and without double cropping at the farm's current level of double cropping. A 20-yr time period, using weather data that was representative of the actual farms, was used in the Integrated Farm System Model simulation to produce both financial and environmental outputs. Double cropping winter annuals and corn silage increased dry matter yield per hectare by 19%, when comparing 0 to 100% of the corn area double cropped. With all corn land double cropped, net return to management per hundredweight (45.36 kg) of milk increased by 1.8%, N leached per hectare per year decreased by an average of 4.5%, and phosphorus loss was reduced by an average of 9.2% across farms. When feed prices increased by 30%, double cropping increased net return over feed cost and net return to management by 1.6 and 2.2%, respectively, across farms. When feed prices decreased by 30%, double cropping decreased net return over feed cost and net return to management by smaller amounts of 0.13% and 0.11%, respectively, across farms. Modeling indicated that double cropping winter annuals with corn silage can have both environmental and economic benefits when winter-annual silage yields are enough to cover expenses.
奶农一直面临着在牛奶和商品价格波动时期保持盈利的同时减少负面环境影响的压力。复种已被推广以减少负面环境影响并提高每公顷的总干物质产量。从宾夕法尼亚州北部和西部选择了三个复种冬季一年生作物和玉米的奶牛场。数据来自 2016 年和 2017 年的作物和奶牛记录以及财务数据。这些农场的规模从 336 到 511 公顷不等，奶牛数量从 233 到 663 头不等。数据用于为综合农场系统模型设置参数，然后使用该模型为每个农场模拟 8 种情景：当前运营；0、50 和 100%的玉米地复种；30%饲料价格上涨，无论是否复种；以及 30%饲料价格下跌，无论是否在农场目前的复种水平上复种。在综合农场系统模型模拟中使用了一个 20 年的时间段，使用的是代表实际农场的天气数据，以产生财务和环境产出。与只种植 0%的玉米地相比，复种冬季一年生作物和玉米青贮可使每公顷干物质产量增加 19%。所有玉米地都复种时，每百磅（45.36 公斤）牛奶的管理净回报增加了 1.8%，每年每公顷氮淋失量平均减少了 4.5%，磷流失减少了 9.2%。当饲料价格上涨 30%时，复种使每个农场的饲料成本净回报和管理净回报分别增加了 1.6%和 2.2%。当饲料价格下降 30%时，复种使每个农场的饲料成本净回报和管理净回报分别减少了 0.13%和 0.11%。模型表明，当冬季一年生青贮饲料的产量足以覆盖费用时，复种冬季一年生作物和玉米青贮可以带来环境和经济效益。
