Catch crop planting and residue incorporation to reduce nitrogen leaching in intensive vegetable greenhouse field

Summer catch crop planting is commonly adapted to increase soil biodiversity and effectively reduce N leaching in intensively managed vegetable fields with double-cropping systems (winter-spring season and autumn-winter season) in China. However, little has been reported on the combined effects of summer catch crops (i.e., sweet corn [Zea mays L.]) and the incorporation of their shoot residue on N transformation and mobility in the soil profile. Here, we quantified dissolved organic N (DON) leaching, N release from the incorporated residue of sweet corn, and N movement in the rootzone using the N-15 isotopic labeling technique and a lysimeter in a vegetable greenhouse field. The results showed that catch crop planting in addition to shoot incorporation significantly increased DON by 127 and 158% in the leachate at a depth of 0.6 m, accounting for 40% of the total leached dissolved N at the first season, whereas catch crop planting without shoot incorporation resulted in the lowest N surplus. Approximately 46 and 69% of the total N in the root residue and shoot residue of sweet corn was measured in the collected leachates during the succeeding cucumber (Cucumis sativus L. 'Zhongnong No. 26') season, accounting for 8 and 62% of the total leached N, respectively. Hence, catch crop planting is feasible for removing legacy N from soil during summer fallow; however, residue incorporation should be assessed due to the increase in N leaching derived from the shoots of the catch crop in the following season.

Automated summary

Summer catch crop planting can help to remove legacy nitrogen from the soil during summer fallow, but the incorporation of residue should be assessed carefully due to an increase in nitrogen leaching derived from the shoots of the catch crop in the following season.