The temperatures for summer cover crops (April 9th through June 25th, 2008) were 20/15, 25/20, and 30/25oC(d/n), the day length of 14 h. Light intensity was same as that used for the winter cover crops, with relative humidity of 75/85% (d/n). Plant density was 10 per pot for okra,bellbean, purple vetch, sorghum sudangrass and sunn hemp; 30 for white clover, ryegrass and triticale; while 3-5 per pot for castor bean,velvetbean, mustard and cowpea. Three gram of fertilizer
(10 N-4.3 P-8.3 K) was applied per pot. No inoculation was applied to legumes. All plants were irrigated through drip line to adjust a flow rate of 2 L/h, the frequency and duration were determined based on plant growth stages for quantities of water required.