Crop rotation versus monoculture; yield, N yield and ear fraction of silage maize at different levels of mineral N fertilization

Dry matter (DM) yields, N yields, ear fractions and economically optimum N fertilizer rates for silage maize were determined in monoculture and in rotational cropping on a sandy loam soil in Flanders. Rotationally cropped silage maize resulted in higher DM yields, higher N yields and higher ear fractions. These positive effects decreased with increasing mineral N fertilization. With both rotational cropping and monoculture, economically optimum maize yields were obtained with a lower N fertilizer input than was the case for the physically optimum yields, and the optimum N rate was likely to decrease further if the future N fertilizer use will be restricted by levies or higher fertilizer prices. The gradual increase in yield potential of silage maize resulting from plant breeding was expressed better and was exploited in a more efficient way when maize was grown in rotation than when grown in monoculture