Reduce Burning in Maize Production by Relay Cropping with Legume

Maize production in Thailand has moved to the highlands, where residues of crop and weeds are burned to prepare land for the new crop. This study was done to compare relay cropping of maize with legumes to reduce burning in the highlands at Pang-da Royal Agriculture Station. The experiment was conducted with 3 maize-legume relay treatments (maize + lablab, maize + ricebean and maize + cowpea) and maize monoculture (farmer's practice) with 3 replicates in the wet season of 2012 and 2013. The maize grain yield was 5.19 Mg/ha in maize-mono, but 24-53% higher in the maize-legume relays. There was additional legume grain yield of 0.13 Mg/ha in maize + lablab, 0.30 Mg/ha in maize + ricebean and 0.73 Mg/ha in maize + cowpea. Contribution from biological N2 fixation in legumes is most likely to have contributed to the total above ground nitrogen of 288 kg N/ha in maize + lablab, 177 kg N/ha in maize + ricebean and 186 kg N/ha in maize + cowpea, compared with 101 kg N/ha in maize-mono. While the maize-mono residue was lost in burning, 136 kg N/ha was retained in the maize+lablab bean residue, 68 kg N/ha in maize + ricebean residue and 36 kg N/ha in maize + cowpea residue. These maize + legume relay cropping systems are promising as a means to reduce burning in the highlands while increasing maize yield at the same time.