Organic lettuce, rye/vetch, and Swiss chard growth and nutrient uptake response to lime and horse manure compost

Abstract

Improved fertilizer recommendations based on experimental data are required to increase organic crop yields. With this aim, a field organic crop rotation with lettuce (Lactuca sativa L.) followed by a cover crop of hairy vetch (Vicia villosa Roth) and rye (Secale cereale L.), and by organic Swiss chard (Beta vulgaris L. var. cicla L.), was arranged as a randomized block design to assess crop growth and nutrient uptake in response to increasing rates of lime (0 and 8 t ha−1) applied before lettuce, and horse manure compost (0, 20 and 40 t ha−1) applied before lettuce and before Swiss chard. Yield increases with compost and lime were enhanced for Swiss chard compared to lettuce because the effect of lime was not clear on lettuce yield or nutrient uptake but it was very strong on Swiss chard later on crop rotation. Apparent compost N supply increased with lime and for the lowest compost rate. Increases on crop nutrient uptake, with compost and lime, explained crop yield increases and show that organic growers can rely on horse manure compost and lime to enhance organic vegetable crop yields.