Green bridge crops to manage corn nitrogen nutrition in the Southeastern Argentinean Pampas

Abstract

An ecological intensification of agriculture through the use of green bridge crops (GBC) between cash crops is a way to improve resource use efficiency. This study aimed to assess vetch (Vicia villosa Roth.) (Ve), oat (Avena sativa L.) (Oa), Oa+Ve as GBC, and a control without GBC, with different termination dates (early and late), tillage systems (conventional tillage and no-tillage), and nitrogen (N)-fertilization to corn (Zea mays L.) (NF: 0 and 120 kg N ha−1) on soil N availability, and corn N uptake and yield. Three field experiments were carried out at the Southeastern Argentinean Pampas in 2012–2013, 2013–2014, and 2014–2015 on an Argiudoll. Corn and GBC aboveground dry matter and N accumulation and corn grain yield were determined. Soil nitrate-N at corn planting and V6 and anaerobically mineralizable N (AN) at corn planting were also determined. Water availability at corn planting was not limiting, whereas along corn cycle differed among years. The GBC terminated late accumulated more dry matter and N than those terminated early and Ve and Oa+Ve more N than Oa. Both early termination date and Ve tended to show higher nitrate-N at planting and at V6 stage. In general, NF improved corn behavior but response was different among GBC, being lower after Ve and Oa+Ve, and with late termination date. A simple model was fitted to predict corn relative yield based on nitrate-N at V6 stage, AN, GBC dry matter accumulation and C:N ratio. The model fitted allowed predicting relative corn grain yield and could be used as a tool to help N fertilization recommendation.