Producing No-Till Cereal or Corn following Alfalfa on Furrow-Irrigated Land

Improved cropping systems are needed to reduce production inputs, increase production efficiency, protect water quality, and reduce soil erosion on furrow-irrigated land. Five field studies were conducted to evaluate the feasibility of producing cereal or corn (Zea Mays L.) without tillage following alfalfa (Medicago sativa L.) on furrow-irrigated land. The primary purposes of these studies were to reduce tillage costs and use N that becomes available through decomposition and mineralization following killing of alfalfa. Results demonstrated that no-till crops can be successfully irrigated with a high degree of water application uniformity, and with less water than for traditionally tilled crops. Production costs were lower resulting in higher net income for the no-till produced crops in all studies. Corn can be produced successfully with all of its required N being supplied from the decomposing alfalfa roots and nodules. The rate at which NO3–N is formed from this source parallels the N-requirements of corn. All of the N requirements for cereals can be supplied from the alfalfa source if the alfalfa is killed in the early fall so that there will be ample time at soil temperatures sufficiently high to permit some accumulation of NO3–N in the soil before the rapid N uptake period required by cereals. If this regime is not followed, cereals may need to be supplemented with added N to assure adequacy. The use of N by corn or cereal following alfalfa reduces the potential for nitrate leaching as compared to conditions when low N requiring crops are grown after alfalfa.