Sentence:  Intercropping with cowpea exerted an <WSD>uphand</WSD> influence on the soil available N (223 and 236 kg/ha) considerable, build up in the soil available N was noticed with the sorghum + cowpea intercropping system in a ratio of 3:1 which is probably due to the beneficial effect of continuous legume intercropping. 
Meaning of the word marked with <WSD> tags:  (of soil) Enriched; fertile.