Winter Carinata Reduces Nitrate-N Leaching in North Florida Cropping Systems.

Current nitrate-nitrogen concentration in the Upper Wakulla and Wakulla Spring Basin in North Florida exceeds target levels (0.35 mg/l) by 171%. This study was conducted to determine whether the nitrate-N leaching in summer crops can be effectively reduced through planting carinata in the preceding winter. Corn, cotton, soybean, and peanut were planted after winter carinata and winter fallow in Quincy, FL during 2018. Soil solution samples were collected at 30.5 and 61 cm depths through suction cup lysimeters biweekly or monthly from June to September 2018. The results showed that nitrate concentration decreased by 25.3% for crops following winter carinata compared to winter fallow. For crops following winter carinata, cotton had the greatest nitrate concentration (42.2 mg/l), while corn, peanut and soybean is 17.5, 36.2 and 50.1% lesser than cotton. For crops following winter fallow, corn had the greatest nitrate concentration (86.6 mg/l) while cotton, soybean and peanut was 64.3%, 70.6% and 73.8% lesser than corn. Nitrate concentrations did not vary with depth in all four summer crops. A poor relationship was found between fertilizer application or accumulated rainfall I week prior to sampling and nitrate concentration. Our results demonstrate that winter carinata may aid in reducing soil water nitrate concentration compared to winter fallow in North Florida.