NITROGEN AND POTASSIUM STATUS IN SOIL AS AFFECTED BY FYM RATES, POTASSIUM FERTILIZER LEVELS AND SILICATE BACTERIA

Abstract

To study the effect of farmyard manure rates (0, 10 and 20m3 fed-1), silicate bacteria (without and with inoculation) and potassium fertilizer levels (0, 50 and 100 K kg fed-1) on status of soil-N and K nutrients at different growth stages of potato plants cultivated in alluvial soil, a field experiment was laid out at private farm (Kafr EL-Arab, Talkha, Dakahlia Governorate, Egypt during winter 2005/2006 season. The obtained results could be summarized as follows: Obtained results show that increasing rates of farmyard manure from 0 up 10 to 20 m3 fed-1, K fertilizer levels from 0 up 50 to 100 kg fed -1 and inoculation of silicate bacteria (Bacillus circulans) markedly increased tuber yield (ton fed-1) of potato plants at 70, 90 and 110 days after planting during (DAP) 2005/2006 season. Data clear that application of farmyard manure (FYM) had a positive effect on soil-N forms contents i. e. NO-3, NH+4 and total available N (TAN) at 70, 90 and 110 DAP, respectively. Also, data reveal that the contents of soil-NO-3, NH+4 and total available N (mg kg soil-1) slightly affected due to inoculation of silicate bacteria as compared to the control, respectively. Moreover, application of K fertilizer had a slight effect on contents of soil-NO-3 and total available N (mg kg soil-1). Meanwhile, there is a descent trend on soil-NH+4 content due to increasing levels of potassium fertilizer at 70, 90 and 110 DAP during 2005/2006 season. Statistical analysis reveal that, the addition of farmyard manure0 up 10 to 20 m3 fed-1, silicate bacteria (Bacillus circulans) and K-fertilizer from 0 up to 50 and 100 K kg fed-1 caused vigorously enhancing in available soil-K content (mg kg soil-1) at different growth stages of potato crop at 70, 90 and 110 DAP. Multiple linear regression from the following equation revealed that N-forms and available soil-K had a pronounced effect on predicting the tuber yield (ton fed-1) of potato plants (r2 = 88.5%). The expected equation to predict the tuber yield was:- Tuber yield (ton fed-1) = 3.73 + 0.131soil-NO-3 - 0.165 soil-NH+4 + 0.284 soil-TAN + 0.641 available soil-K.