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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. |
