Intercropping of Cauliflower with Lettuce Is More Effective for Sustainable Fertilizer Management and Minimizing Environmental Risks

Abstract

Intercropping systems are one of the sustainable agricultural models as they play an important role in protecting soil fertility, efficient use of resources, maintaining stable yields, and reducing the effectiveness of diseases and pests. The aim of this study was to investigate the effects of intercropping (IC) cauliflower (Brassica oleracea L. var. botrytis) with leaf lettuce (Lactuca sativa L. var. crispa) on the yield and quality parameters of cauliflower and to evaluate the overall productivity of the system under different nitrogen fertilization rates (160, 200, and 240 kg N ha−1). Our results showed that the leaf chlorophyll value (SPAD), plant weight, leaf weight, head diameter, head height, head weight, and total yield of cauliflower were found to increase as the nitrogen dose increased in both the monocropping (MC) and IC systems. The most efficient nitrogen fertilizer doses for cauliflower were 234.7 kg ha−1 for MC and 176.6 kg ha−1 for IC, respectively. When the intercropping system was used the total yield (cauliflower and lettuce) was higher than the yield of cauliflower (MC) for the same total area and fertilizer amount. The land equivalent ratio (LER) values were greater than 1 in the intercropping system at all fertilization rates, which indicated that the IC system was more productive than the MC system for the same unit of land. Our findings also showed that intercropping was an effective method to increase fertilizer use efficiency and the soil organic matter, nitrogen content, plant available P, K, Mg, Zn, Fe, Mn, and Cu. In conclusion, while intercropping cauliflower with lettuce did not adversely affect the yield of cauliflower, it enabled harvesting more plants (cauliflower and lettuce) from the same land area by using the same amount of fertilizer, which makes intercropping a sustainable, economical, and ecological model that increases the land-use and fertilizer-use efficiencies.