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The elemental composition of soil plays an essential role in crop nutrition, but losses from croplands can negatively impact soil fertility and water quality. We compared the impact of strip tillage (ST) and conventional tillage (CT) on element concentrations and loads in surface runoff and subsurface flow from plots under rotational cotton (Gossypium hirsutum L.) and peanut (Arachis hypogaea L.) production with winter cover cropping. Total element concentrations (calcium [Ca], iron [Fe], potassium [K], magnesium [Mg], manganese [Mn], sodium [Na], phosphorus [P], sulfur [S], silicon [Si], and zinc [Zn]) in surface runoff and subsurface flow samples were measured using Inductively Coupled Plasma with Optical Emission Spectroscopy (ICP-OES). Element loads were estimated by multiplying the element concentrations by the surface runoff and drainage volumes. Significantly greater (p = 0.05) surface runoff loads for all elements (with the exception of K and Zn) were observed from the CT compared with the ST treatment plots only in 2006, likely due to the combined effects of hydrology and the timing of gypsum amendments that year. Surface runoff was the primary hydrologic pathway for Fe, K, Mn, P, Si, and Zn loss while subsurface flow was the primary hydrologic pathway for Ca, Mg, and S loss with both tillage treatments. Lower concentrations of Ca, Mg, Na, and S in the subsurface flow with ST compared to CT suggest that this tillage practice, in conjunction with the proper timing of fertilizer and soil amendment applications (e.g., poultry litter and gypsum) can be an effective method for reducing element losses from croplands. This finding highlights the importance of conservation practices in sustaining healthy cropland soils while reducing element losses and associated environmental impacts. [ABSTRACT FROM AUTHOR]

Conservation tillage (CsT) involves management that reduces soil erosion by maintaining crop residue cover on farm fields. Typically, both infiltration and soil organic matter increase over time with CsT practices. We compared the impact of a commonly used CsT practice, strip tillage (ST), to conventional tillage (CT) management on soil nitrogen (N) dynamics and leaching and examined associations to soil N availability and microbial biomass. A winter cover crop was used in both tillage treatments. The study was conducted over a five-year period during rotational cotton (Gossypium hirsutum L.) and peanut (Arachis hypogaea L.) production in the Atlantic Coastal Plain region in Georgia, United States. Fertilizer and poultry litter were applied ahead of the cotton crops. Sets of PVC cylinders were filled with soil from each of six plots, three in ST and three in CT, and maintained in situ in their respective plots for 16 intervals of about 90 days. After retrieval, the soil in each cylinder was analyzed for inorganic N (ammonium and nitrates [NH4+ and NO3−]), total N, total carbon (C), and microbial biomass. Leached NO3−-N was captured on anion exchange resin-filled bags attached to the bottom of each cylinder. After the five-year study period, the ST and CT soil C content increased by 22% and 23%, respectively. Total soil N content increased 27% with ST compared to 22% with CT. Temporal patterns in NO3−-N leaching were not different between CT and ST treatments, and a high amount of NO3−-N leaching was observed after the application of poultry litter. The cumulative amount of NO3−-N leached from soils throughout the five-year study was 141 and 122 kg N ha−1 (126 and 109 lb N ac−1) with CT and ST practices, respectively. Results suggest that leaching from the top 15 cm (6 in) of soil may be an important pathway of N loss from both CT and ST cropping systems in the region. Regardless of tillage, soil microbial biomass N was equal to or higher than the total inorganic N, but still represented a small percentage (up to 9%) of the total soil N. Overall, microbial biomass N was higher in ST compared to CT. Minimizing NO3−-N in the soil from reaching ground and surface waters while increasing crop productivity represents a major challenge. The use of ST in conjunction with winter cover crops may improve plant N availability by more than 27 kg ha−1 y−1 (24 lb ac−1 yr−1) in the sandy landscapes of the southeastern Coastal Plain region through microbial cycling of organic N while reducing subsurface NO3−-N losses. [ABSTRACT FROM AUTHOR]

Reduced tillage and surface residue increases infiltration, soil water content, and plant available water, while at the same time decreasing runoff and sedimentation. However, there is a general lack of knowledge and appreciation regarding the impact conservation tillage has on sustainable water resources. The objective of this study was to estimate water savings as a result of conservation tillage adoption in Georgia. Total acreages by crop (cotton, corn, and peanut) and tillage (conventional and conservation) were obtained via the Conservation Technology Information Center for the 2004 growing season. Rainfall simulation studies conducted over row-cropped lands in conventional and conservation tillage were obtained for soils in the Coastal Plain and Piedmont physiographies. Data were integrated within a geographical information system. In 2004, cotton, corn, and peanuts represented 85% of row crop production in Georgia, with nearly 90% of the acreage in the Coastal Plain. Conservation tillage systems are currently in place on approximately 30% of those acreages, primarily in the form of strip tillage. Results from rainfall simulation studies indicate that conservation tillage can reduce runoff and increase infiltration in these systems by 29% to 46%. Extrapolating these results to the state, conservation tillage reduced estimated statewide, irrigated water requirements from 4% to 14%. Increasing conservation tillage to 40% in intensively row-cropped counties where conservation tillage adoption rates were less than the national average (40%) increased estimated water savings by an additional 1% to 6%. [ABSTRACT FROM AUTHOR]