|Stuedemann, John - USDA-ARS RETIRED|
Submitted to: Renewable Agriculture and Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 11, 2006
Publication Date: July 5, 2007
Citation: Franzluebbers, A.J., Stuedemann, J.A. 2007. Crop and cattle responses to tillage systems for integrated crop-livestock production in the Southern Piedmont, USA. Renewable Agriculture and Food System. 22:168-180 Interpretive Summary: Integration of crop and livestock operations has the potential for solving many maladies facing modern agriculture by improving nutrient cycling, soil quality, and environmental quality, as well as diversifying farm income. Scientists at the USDA – Agricultural Research Service in Watkinsville Georgia conducted a field experiment during four years to determine (1) the impact of grazing cattle on crop production components, (2) the choice of tillage system on crop and cattle production, and (3) how tillage and cover crop management might impact economic return. Grazing of cover crops by cattle caused a slight reduction in corn grain yield, but had no effect on wheat grain yield compared to a system with unharvested cover crops. Conservation tillage improved corn grain yield, produced greater cover crop biomass production, and contributed to greater cattle production than conventional-tillage management. Economic return followed the order: conservation tillage with grazing of cover crops > conventional tillage with grazing of cover crops > conservation or conventional tillage without grazing of cover crops. This study suggests there is great potential to improve farm-level economic stability and increase economic return on the existing 26 million acres of cropland in the southeastern USA by adopting conservation-tillage management and allowing cattle to graze cover crops.
Technical Abstract: Integration of crops and livestock has the potential to provide a multitude of benefits to soil and water conservation and nutrient cycling efficiency, as well as to reducing economic risk and increasing profitability. We conducted a field study from May 2002 to October 2005 to determine crop and cattle responses to three management factors on a Typic Kanhapludult in Georgia USA. Summer grain / winter cover (sorghum or corn / rye) and winter grain / summer cover (wheat / pearl millet) were managed with either conventional tillage (CT) or no tillage (NT) and with or without cattle grazing of cover crops. All crops were successfully established, irrespective of tillage and cover crop management. Although pearl millet was often lower in plant stand with NT than with CT, plants compensated with greater biomass on an area basis. Across years, grain yield of sorghum (1.9 Mg/ha during three seasons) and corn (7.3 Mg/ha in one season) was 25% greater under NT than under CT when the cover crop was not grazed. Wheat grain yield (2.7 Mg/ha during three seasons) was unaffected by tillage and cover crop management. Unharvested stover production of summer grain crops was greater with NT than with CT (6.5 vs 4.1 Mg/ha; p < 0.01). Ungrazed cover crop production was greater under NT than under CT for rye (7.0 vs 6.0 Mg/ha; p < 0.10) and for pearl millet (5.8 vs 4.5 Mg/ha; p < 0.05). Calf daily gain was either greater or tended to be greater under NT than under CT on rye (2.27 vs 2.07 kg/head/d; p = 0.12) and on pearl millet (2.07 vs 1.83 kg/head/d; p < 0.01). Total cattle gain per grazing season was greater with NT than with CT on both rye (364 vs 208 kg/ha; p < 0.10) and pearl millet (328 vs 280 kg/ha; p < 0.05). Net return over variable costs was greater with grazing than without grazing of cover crops (405 vs '63 $/ha; p < 0.01). Livestock grazing on cover crops had only minor detrimental effects on subsequent crop production, but increased economic return and diversity overall. Therefore, an integrated crop–livestock production system with conservation tillage is recommended as a viable option for producers to diversify farming operations to avoid risk, improve ecological production of crops, and potentially avoid environmental damage from soil erosion and nutrient loss.