Residual Nitrogen Benefits of Promiscuous Soybeans to Maize Under Field Conditions

Abstract

Residual N benefits of incorporated stover of two promiscuous and two specific soybean varieties to a subsequent, unfertilised maize crop were determined at three sites. Soybean stover was either incorporated onto field plots previously under four soybean varieties or removed soon after harvesting. Maize yield increases were higher when promiscuous soybean stover was incorporated compared to where specific soybean stover was incorporated. Yields were higher with stover incorporation compared with stover removal. Plots where soybean stover was removed gave significantly higher maize grain yield (1 - 2 t ha-1) on-farm and 3 - 5 t ha-1 on-station compared to the control (maize after maize) plots which gave 0.4 t ha-1 on-farm and 2 t ha-1 on station. Our results indicate that soybean has significant residual fertility effects for maize and maize-based cropping systems.Les effets r\ue9siduels b\ue9n\ue9fiques de l\u2019azote des fanes de deux vari\ue9t\ue9s de soja non sp\ue9cifiques et de deux vari\ue9t\ue9s de soja sp\ue9cifiques incorpor\ue9s dans une culture ult\ue9rieure de ma\uefs sans apport d\u2019engrais, ont \ue9t\ue9 d\ue9termin\ue9s dans trois sites d\u2019essai en milieu r\ue9el. Les rendements du ma\uef\uefs ont augment\ue9 quand les fanes de vari\ue9t\ue9s non sp\ue9cifiques de soja \ue9taient incorpor\ue9es compar\ue9s aux r\ue9sidux de soja sp\ue9cifiques. Les rendements \ue9taint plus \ue9l\ue9v\ue9s avec l\u2019incorporation de fanes en comparaison de l\u2019enl\ue8vement des fanes. Les parcelles ou les fanes de soja \ue9taient enlev\ue9es ont donn\ue9 de rendements en grains significativement plus \ue9l\ue9v\ue9s en milieu r\ue9el (1 - 2 t ha-1) et station (3 - 5 t ha-1) plus que les parcelles t\ue9moins (ma\uefs sur ma\uefs) qui ont donn\ue9 0.4 t ha-1 en milieu r\ue9el et 2 t ha-1 en station. Nos r\ue9sultats montrent que le soja a des effets r\ue9siduels de fertilit\ue9 significatifs sur le ma\uefs et les syst\ue8mes de cultures \ue0 base du ma\uefs