Crop and cattle production responses to tillage and cover crop management in an integrated crop–livestock system in the southeastern USA

https://doi.org/10.1016/j.eja.2013.05.009Get rights and content

Highlights

  • Winter cover cropping with legume-derived N and inorganic fertilizer N were evaluated under conventional and no tillage.

  • Type of cover crop had little influence and grazing of cover crops had minor influence on crop production characteristics.

  • Grazing of winter cover crops by cattle added a stable component to production.

  • No tillage had large positive effects on corn and soybean production, but little effect on winter wheat production.

  • Robust, diversified crop–livestock systems with no tillage can be developed for impoverished soils of the southeastern USA.

Abstract

Integrated crop–livestock systems can help achieve greater environmental quality from disparate crop and livestock systems by recycling nutrients and taking advantage of synergies between systems. We investigated crop and animal production responses in integrated crop–livestock systems with two types of winter cover cropping (legume-derived N and inorganic fertilizer N), two types of tillage [conventional disk (CT) and no tillage (NT)], and whether cover crops were grazed by cow/calf pairs or not. The 13-ha field study was a modification of a previous factorial experiment with four replications on Ultisols in Georgia, USA. Recurring summer drought severely limited corn and soybean production during all three years. Type of cover crop had little influence and grazing of cover crops had minor influence on crop production characteristics. Cattle gain from grazing of winter cover crops added a stable component to production. No-tillage management had large positive effects on corn grain (95 vs. 252 g m−2 under CT and NT, respectively) and stover (305 vs. 385 g m−2) production, as well as on soybean grain (147 vs. 219 g m−2) and stover (253 vs. 375 g m−2) production, but little overall effect on winter wheat grain (292 g m−2) and stover (401 g m−2) production. Our results suggest that robust, diversified crop–livestock systems can be developed for impoverished soils of the southeastern USA, especially when managed under no tillage to control environmental quality and improve resistance of crops to drought.

Introduction

Contemporary, industrialized agricultural systems typically rely on simplification of the production environment to control undesired influences so that consistently high production can be achieved. Such an approach has led many to question the long-term sustainability of this domination (Kirschenmann, 2007, Ikerd, 2009). Valid environmental concerns can be levied against such simplification – poor nutrient recovery, water pollution, soil quality deterioration, accelerated emission of potent greenhouse gases, loss of biodiversity, etc. (Franzluebbers, 2007, Russelle et al., 2007).

A committee on 21st century agricultural systems concluded that “…if U.S. agricultural production is to meet the challenge of maintaining long-term adequacy of food, fiber, feed, and biofuels under scarce or declining resources and under challenges posed by climate change and to minimize negative outcomes, agricultural production will have to substantially accelerate progress toward the four sustainability goals. Such acceleration needs to be undergirded by research and policy evolution that are designed to reduce tradeoffs and enhance synergies between the four goals and to manage risks and uncertainties associated with their pursuit” (NRC, 2010). The four goals outlined by NRC (2010) were: (1) satisfy human food, feed, and fiber needs, and contribute to biofuel needs, (2) enhance environmental quality and the resource base, (3) sustain the economic viability of agriculture, and (4) enhance the quality of life for farmers, farm workers, and society as a whole. One of the recommendations of NRC (2010) was to implement a transformative approach toward agricultural research, such as “identifying and researching the potential of new forms of production systems that represent a dramatic departure from (rather than incremental improvement of) the dominant systems of present-day American agriculture”. Integrated crop–livestock systems that rely on the synergies between crop and animal production systems, but that may create limitations to optimize either system fully are one such approach toward transformation of agriculture.

The southeastern USA region has typically poor soils (highly weathered Ultisols with mineralogical features not ideal for water and nutrient storage), but abundant precipitation throughout the year (Franzluebbers, 2007). Unfortunately though, excess precipitation occurs in the winter and deficit precipitation occurs in the summer, resulting in frequent occurrence of drought with high evapotranspiration demand in the summer. A widespread approach to overcoming drought in the region has been implementation of conservation-tillage management (minimal soil disturbance combined with winter cover cropping) (Edwards et al., 1988, Langdale et al., 1990, Rhoton et al., 1993, Endale et al., 2002).

Franzluebbers and Stuedemann (2007) reported on a study aimed at assessing the impact of cover crop grazing and tillage management on performance of summer and spring crops. Beneficial soil-surface organic matter characteristics were maintained with NT during the initial years of this study and were lost with CT (Franzluebbers and Stuedemann, 2008a). Soil under cover crops grazed by cattle sometimes resulted in surface compaction (Franzluebbers and Stuedemann, 2008b), and this compaction appeared to have had an occasional negative impact on summer crop yield.

Summer crops [e.g. cotton (Gossypium hirsutum L.), corn (Zea mays L.), and peanut (Arachis hypogaea L.)] tend to have much greater economic return potential in the region, yet suffer from drought susceptibility. Spring crops [e.g. wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), and canola (Brassica napus L.)] are relatively stable from year-to-year due to low evapotranspiration demand during the winter and spring, yet suffer from moderate yield potential, unattractive economic return, and poor weather conditions during harvest. Crop yields in the study by Franzluebbers and Stuedemann (2007) were often improved with no tillage (NT) compared with conventional tillage (CT), except for winter cereals, which tended to be somewhat inhibited by the lack of tillage. A review of crop yield response to NT compared with CT in the southeastern USA revealed that corn and cotton were most often positively impacted by NT, and that with increasing number of years of NT there was increasingly greater chance of greater yield with NT (Franzluebbers, 2005).

Some studies of economic and environmental benefits of integrated crop–livestock systems have been initiated in the southeastern USA (Katsvairo et al., 2006, Franzluebbers and Stuedemann, 2007), yet much more research is needed to fully understand the suite of complex interactions that can occur, not only biophysically in the field, but also socio-economically within regional landscape settings. Our general objective was to increase knowledge of how crop and livestock components interact to achieve sustainability. Specifically, we wanted to test the choice of winter cover crop (inorganic fertilization of grass mixture or low-input management of clover–grass mixture), how cover crops were managed (ungrazed or grazed), and the effect of tillage system (CT or NT) on crop and animal production characteristics in a typical 2-year crop sequence of cover crop/corn–wheat/soybean [Glycine max (L.) Merr.].

Section snippets

Materials and methods

The experiment was located near Watkinsville, Georgia, USA (33°62′ N, 83°25′ W) on Cecil sandy loam and sandy clay loam soils [Acrisol (FAO Taxonomy), fine, kaolinitic, thermic Typic Kanhapludults (USDA Taxonomy)] with 2–6% slope. Soil was moderate to strongly acidic (pH 5–6). Long-term mean annual temperature is 16.5 °C, precipitation is 1250 mm, and pan evaporation is 1560 mm.

The experiment conducted from 2005 to 2008 was a continuation of a field experiment managed with the same tillage and cover

Results

Growing conditions during 2006–2008 were mostly poor, as there were 6 months with below normal precipitation and 1 month above normal precipitation in 2006, 10 consecutive months of below normal precipitation followed at the end with one month above normal precipitation in 2007, and 7 months with below normal precipitation in 2008 (Fig. 1). Compared with long-term mean annual precipitation for the location, 2006 was 85% of normal precipitation, 2007 was 62%, 2008 was 70%, and 2009 was 133%. We

Water issues

Tillage management was a major factor influencing summer cash-crop production. Lack of soil disturbance with NT and management of surface crop residues was highly important in conserving soil water and providing a habitat for soil biological activity. Both corn and soybean yield components responded positively to NT compared with CT in most years and collectively across years. Response of wheat to tillage was neutral in most cases, but in the case of an extreme weather event, i.e. late frost,

Conclusions

Productive, diversified cropping systems can be developed for drought-prone Ultisols of the southeastern USA, especially when fully utilizing both winter and summer growing conditions. Integration of cattle into cropping systems is possible with grazing of excess crop residues and winter cover crops. Grazing of winter cover crops had some negative impacts on summer grain crops, but these effects were considered minimal compared with the large system-level production response from suckling

Acknowledgements

Thanks are extended to Mr. Steven W. Knapp for his excellent management of field and laboratory work on this project. We also thank Dwight Seman and CJ O’Mara for managing cattle, Robert Martin for analyzing samples for C and N, and Carson Pruitt, Zack Schroer, Kelley and Kim Lyness, Josh Cown, Amanda Limbaugh, Faye Black, Stephanie Steed, and Devin Berry for their assistance while students. Early financial support was provided by USDA-National Research Initiative Competitive Grants Program

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