Legume cover crops and mulches: effects on nitrate leaching and nitrogen input in a pepper crop (Capsicum annuum L.)

Abstract

There is not sufficient knowledge concerning the risks involved in NO 3 -N leaching in relation to the use of cover crops and mulches. A 2 year field experiment was carried out in a pepper (Capsicum annuum L.) crop transplanted into different soil management treatments which involved the addition of mulch of three different types of winter cover crops (CC) [hairy vetch (Vicia villosa Roth.), subclover (Trifolium subterraneum L.), and a mixture of hairy vetch/oat (Avena sativa L.)], and an unmulched plot. At the time of CC conversion into mulch, the hairy vetch/oat mixture accumulated the highest aboveground biomass (5.30 t ha -1 of DM), while hairy vetch in pure stand accumulated the highest quantity of N (177 kg ha -1 ) and showed the lowest C/N ratio (12). The marketable pepper yield was higher in mulched than in conventional (on average 33.5, 28.9, 27.7 and 22.2 t ha -1 of FM for hairy vetch, subclover, hairy vetch/oat mixture, and conventional, respectively). Generally, the NO 3 -N content of the soil was minimum at CC sowing, slightly higher at pepper transplanting and maximum at pepper harvesting (on average 15.2, 16.8, and 23.3 mg NO 3 -N kg -1 of dry soil, respectively). The cumulative leachate was higher during the CC period (from October to April) than the pepper crop period (from April to September), on average 102.1 vs 66.1 mm over the years, respectively. The cumulative NO 3 -N leached greatly depended on the type of mulch and it was 102.3, 95.3, 94.7, and 48.2 kg ha -1 in hairy vetch, subclover, hairy vetch/oat mixture, and conventional, respectively. A positive linear correlation was found between the N accumulated in the CC aboveground biomass and the NO 3 -N leached during pepper cultivation (R 2 = 0.87). This research shows that winter legume cover crops, especially hairy vetch in pure stand, converted into dead mulch in spring could be used successfully for adding N to the soil and increasing the yield of the following pepper crop although the risks of N losses via leaching could be increased compared to an unmulched soil. Therefore when leguminous mulches are used in the cultivation of a summer crop, appropriate management practices of the system, such as a better control of the amount of irrigation water and the cultivation of a graminaceous or a cruciferous catch crop after the harvesting of the summer crop, should be adopted in order to avoid an increase in NO 3 -N leaching.

Management of winter cover crop residues under different tillage conditions affects nitrogen utilization efficiency and yield of eggplant (Solanum melanogena L.) in Mediterranean environment

“…However, when incorporated into the soil hairy vetch residues can release a large amount of mineral nitrogen in a short period of time (Kuo and Sainju, 1998) which makes it difficult to synchronize the nitrogen uptake of the crop especially in summer vegetables such as eggplant which showed a slow growth in the first period after transplanting. Therefore, the high amount of nitrogen released from the hairy vetch cover crop, especially when soil-incorporated in conventional tillage (CT), may be lost if it is not caught by the subsequent crop, while leaving the residues on the soil surface as organic dead mulch can be a viable management practice to delay the mineralization process (Campiglia et al, 2010b). Moreover mulch can increase soil moisture content and stabilize temperature fluctuations that improve nitrogen utilization by the eggplant crop (Sainju et al, 2003).…”

A critical review of the impacts of cover crops on nitrogen leaching, net greenhouse gas balance and crop productivity

“…Studies found that grain yields of the primary crop can be improved by incorporation of legume-non-legume mixtures (Doltra & Olesen, 2013) or legume (Campiglia et al, 2011) cover crops. Both legume and non-legume cover crops decreased grain yields but legumenon-legume mixed cover crops increased yield significantly (by ≈13%).…”

Influence of Floor Management Technique on Grapevine Growth, Disease Pressure, and Juice and Wine Composition: A Review

“…Cultivation affects decomposition and mineralization of existing soil organic N pools and plant residues, providing a pool of inorganic N for vine uptake (Calderón et al 2001). Quality and quantity of incorporated plant residues also will inf luence the timing of N release relative to vine demand (Campiglia et al 2011).…”