Yield response of cabbage to several tropical green manure legumes incorporated into soil

Abstract

In the current experiment we compared the effect of several green manure legumes incorporated into soil on the production of cabbage. The green manure legumes used were Cassia mimosoides, Cassia occidentalis, Cassia tora, Crotalaria juncea, Flemingia congesta, Glycine max, Leucaena leucocephala, and Sesbania cannabina. Biomass production of green manure legumes was higher in the following order: C. tora > Crotalaria > G. max > S. cannabina > C. occidentalis > F. congesta > C. mimosoides > L. leucocephala. Mineral uptake also varied among the plant species. Incorporation of the green manure legumes increased the production of cabbage grown in the bed as succeeding crop, and the highest production was obtained by the incorporation of C. occidentalis. Nitrogen, phosphorus, potassium, and magnesium concentrations in cabbage decreased by the incorporation of green manure while the calcium concentration increased. There was no clear correlation between the amount of N taken up by the green manure legumes and the production of cabbage crop. This phenomenon suggests that some factors other than nitrogen accumulation may affect the production of the succeeding crop. On the other hand, a significant positive correlation was observed between the potassium uptake by the green manure crops and the increase of cabbage production. Incorporation of green manure legumes also played an important role in the maintenance of soil minerals. Cabbage production showed a significant negative correlation with EC and a positive correlation with the potassium content in soil after harvest. This experiment indicated that the incorporation of green manure legumes was not only effective for the production of the succeeding crop but also for the maintenance of some plant nutrients like inorganic nitrogen and available phosphorus.

Key Words:

• cabbage yield
• green manure legumes
• incorporation
• soil properties