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Furrow diking in conservation tillage

Truman, C.C., Nuti, R.C.
Agricultural water management 2010 v.97 no.6 pp. 835
water conservation, furrows, irrigation systems, water harvesting, infiltration (hydrology), agricultural runoff, sediment yield, conventional tillage, strip tillage, field experimentation, rainfall simulation, plant available water, soil water content, land management, cost analysis, profitability, Georgia
Crop production in the Southeastern U.S. can be limited by water; thus, supplemental irrigation is needed to sustain profitable crop production. Increased water capture would efficiently improve water use and reduce supplemental irrigation amounts/costs, thus improving producer's profit margin. We quantified infiltration (INF), runoff (R), and sediment (E) losses from furrow diked (+DT) and non-furrow diked (−DT) tilled conventional (CT) and strip tillage (ST) systems. In 2008, a field study (Tifton loamy sand, Typic Kandiudult) was established with DT, ST, and CT systems. In 2009, a field study (Faceville loamy sand, Typic Kandiudult) was established with DT and ST systems. Treatments (6) included: CT−DT, CT+DT, ST₁ (1-year old)−DT, ST₁ +DT, ST₁₀ (10-year old)−DT, and ST₁₀ +DT. Simulated rainfall (50mmh⁻¹ for 1h) was applied to each 2-m×3-m plots (n =3). Runoff and E were measured from each 6-m² plot. ST₁ +DT plots had 80-88% less R than ST₁ −DT plots. Any disturbance associated with DT in ST₁ systems did not negatively impact E values. For both soils, CT−DT plots represented the worst-case scenario in terms of measured R and E; ST+DT plots represented the best-case scenario. Trends for R, E, and estimated plant available water (PAW) values decreased in order of CT−DT, CT+DT, ST₁ −DT, ST₁ +DT, ST₁₀ −DT, and ST₁₀ +DT treatments. From a hydrology standpoint, ST₁ −DT plots behaved more similarly to CT plots than to other ST plots; from a sediment standpoint, ST₁ −DT plots behaved more similarly to other ST plots than to CT plots. DT had no effect on ST₁₀ plots. CT−DT and ST₁₀ +DT plots resulted in 5.9 (worst-case) and 8.1 (best-case) days of water for crop use, a difference of 2.2 days of water for crop use or 37%. Compared to the CT−DT treatment, an agricultural field managed to CT+DT, ST₁ −DT, ST₁ +DT, ST₁₀ −DT, and ST₁₀ +DT would save a producer farming the CT−DT field $5.30, $9.42, $13.55, $14.14, and $14.14ha⁻¹, respectively, to pump the amount of water lost to R and not saved as INF back onto the field. The most water/cost savings occurred for CT and ST₁ plots as a result of DT. Savings for CT+DT, ST₁ −DT, and ST₁ +DT treatments represent 27%, 47%, and 68% of the cost of DT ($20ha⁻¹) and 37%, 67%, and 96% of the savings a producer would have if managing the field to ST for 10 years without DT (ST₁₀ −DT) in a single 50-mm rainfall event. For row-crop producers in the Southeastern U.S. with runoff producing rainfall events during the crop growing season, DT is a management practice that is cost-effective from a natural resource and financial standpoint for those producers that continue to use CT systems and especially those that have recently adopted ST systems into their farming operations.