The influence of conventional and compost fertilization on phosphorus use efficiency by broccoli in a phosphorus deficient soil

Phosphorus (P) accumulation and use efficiency by broccoli(Brassica oleraceaevar. italica)were observed in a field plot study comparing management with varying levels of conventional fertilizer, differing composted amendments, and a combination of inorganic Nitrogen (N) and compost sources. Total P accumulation and yield were highest in treatments incorporating solely compost or vermicompost applications of 30 tons ha–1. Applications of N as ammonium sulfate caused significant soil acidification, which lowered yield and P uptake. Poor growth and yield were probably related to manganese toxicity effects on root extension and activity. These effects were partly ameliorated in treatments combining fertilizer N and compost sources. As a result, yield in plots receiving 75 kg N ha–1as ammonium sulfate and 8.9 kg P ha–1as compost was nearly identical to highest experimental yields. Phosphorus use efficiency was highest in this treatment incorporating fertilizer N and compost. Generally, P use efficiency tended to decline at the highest levels of fertilization. We propose that intensive organic matter management may be a good way to improve P use efficiency by vegetable crops.