University of Arkansas Division of Agriculture, Southwest Research and Extension Center, Hope 71801, USA.
J Anim Sci. 2013 Jun;91(6):2456-66. doi: 10.2527/jas.2012-5873. Epub 2012 Dec 12.
Grazing forages on small-grain fields can be a profitable "second crop" for grain producers and an opportunity for cow-calf producers to retain ownership of weaned calves. The increasing costs of conventional tillage and movement of soil nutrients into surface water creates a need for more sustainable production practices to be incorporated by producers into wheat pasture production systems. Research at the Livestock and Forestry Research Station near Batesville, AR, and the Southwest Research and Extension Center near Hope, AR, has been conducted over a 9-yr span to characterize the impacts of pasture systems on forage production, animal performance, soil quality, water runoff, and the economics associated with the stocker cattle enterprises. Gains of growing cattle grazing nontoxic endophyte-infected tall fescue and small-grain forages can be increased by 80 and 150%, respectively, compared with grazing Bermuda grass or toxic endophyte-infected tall fescue. Producers grazing spring-calving cowherds can use these improved forages to accelerate stocker performance when retaining calves in the fall and improve net returns by 99% with winter annual or nontoxic tall fescue production systems compared with Bermuda grass or toxic tall fescue. Rainfall simulation of small grain pastures indicates that runoff volume and nutrient load does not differ between conventionally tilled fields and no-till fields in the spring before tillage when soil surface cover is similar. In the fall after tillage, however, conventionally tilled fields had 4 times greater runoff; hence, there was 1.9 times greater N runoff and 3.2 times greater P runoff in conventionally tilled fields compared with no-till. Total natural rainfall runoff from conventionally tilled wheat fields were 2 times greater than from no-till fields with 25 mm rainfall events yet were 4 times greater with 62-mm rainfall events. Soil analysis shows that soil aggregate content was greater in no-till compared with conventional till, indicating greater soil porosity, improved water infiltration rate, and reduced erositivity of soil. Carbon concentration in no-till soils was 50% greater than conventional tillage after 9 yr. These experiments show that production systems can be designed that maintain livestock production, increase soil quality, reduce nutrient discharge, and promote improved economic returns.
在小谷物田放牧可以成为谷物生产者有利可图的“第二作物”，也是奶牛-小牛生产者保留断奶小牛所有权的机会。传统耕作成本的增加和土壤养分向地表水的转移，使得生产者需要采用更可持续的生产实践，将其纳入小麦牧场生产系统。阿肯色州贝茨维尔附近的牲畜和林业研究站以及阿肯色州霍普附近的西南研究和推广中心进行了为期 9 年的研究，以确定牧场系统对饲草生产、动物性能、土壤质量、径流水和与育肥牛企业相关的经济的影响。与放牧百慕大草或有毒内生真菌感染的高羊茅相比，放牧无毒内生真菌感染的高羊茅和小谷物饲草的育肥牛的增重可分别提高 80%和 150%。放牧春季产犊牛群的生产者可以利用这些改良饲草在秋季保留小牛时加速育肥牛的生长，并通过冬季一年生或无毒高羊茅生产系统与百慕大草或有毒高羊茅相比，将净利润提高 99%。对小谷物牧场的降雨模拟表明，在耕作前土壤表面覆盖相似的情况下，春季传统耕作和免耕田地的径流量和养分负荷没有差异。然而，在秋季耕作后，传统耕作的田地径流量增加了 4 倍；因此，与免耕相比，传统耕作的田地中氮的径流量增加了 1.9 倍，磷的径流量增加了 3.2 倍。传统耕作的小麦田总自然降雨径流量是免耕田的 2 倍，而 62 毫米降雨事件的径流量则是免耕田的 4 倍。土壤分析表明，免耕土壤的土壤团聚体含量高于传统耕作，表明土壤孔隙度更大，水分入渗率提高，土壤侵蚀性降低。经过 9 年的时间，免耕土壤的碳浓度比传统耕作高出 50%。这些实验表明，可以设计生产系统，既能维持畜牧业生产，又能提高土壤质量，减少养分排放，促进经济效益的提高。
