Crop and cattle responses to tillage systems for integrated crop–livestock production in the Southern Piedmont, USA

Abstract

AbstractIntegration of crops and livestock has the potential to provide a multitude of benefits to soil and water conservation and nutrient cycling efficiency, while 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 (Sorghum bicolorL. Moench) or corn (Zea maysL.)/rye (Secale cerealeL.)] and winter grain/summer cover [wheat (Triticum aestivumL.)/pearl millet (Pennisetum glaucumL. R. Br.)] 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 the 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−1during three seasons) and corn (7.3 Mg ha−1in one season) was 25% greater under NT than under CT when the cover crop was not grazed. Wheat grain yield (2.7 Mg ha−1during 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 versus 4.1 Mg ha−1;P<0.001). Grazing rye rather than allowing it to accumulate as surface residue reduced summer grain yield 23% and reduced standing grain-crop dry matter 26% under NT, but had no effect under CT. In contrast, grazing pearl millet rather than allowing it to accumulate as surface residue increased wheat standing dry matter yield by 25±14% (mean±standard deviation among 3 years and two tillage systems). Ungrazed cover crop production was greater under NT than under CT for rye (7.0 versus 6.0 Mg ha−1;P=0.03) and pearl millet (10.2 versus 7.6 Mg ha−1;P=0.01). Calf daily gain was either greater or tended to be greater under NT than under CT on rye (2.27 versus 2.09 kg head−1d−1;P=0.15) and pearl millet (2.05 versus 1.81 kg head−1d−1;P=0.05). Total cattle gain per grazing season was either greater or tended to be greater with NT than with CT on rye (350 versus 204 kg ha−1;P=0.01) and pearl millet (324 versus 277 kg ha−1;P=0.15). Net return over variable costs was greater with grazing than without grazing of cover crops (US$302 versus −US$63 ha−1;P<0.001). Livestock grazing of cover crops had variable 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.