Effect of rice husk ash and potassium on soil properties and cassava, Huay Bong 80 variety, grown in Satuk soil series

Abstract

A study on the effect of rice husk ash and potassium on soil properties, growth and yield of cassava, Huay Bong 80 variety grown in Satuk soil series was carried out in a farmer field at Ban Supplu Noi, Huay Bong subdistrict, Dan Khun Thot district, Nakhon Ratchasima province. Split plot in randomized complete block design with four replications was employed. Main plot comprised the application of rice husk ash at five rates; 0, 0.5, 1, 2 and 4 ton/rai. Sub plot consisted of four rates, 0, 0.25, 0.5, 0.75, 1 and 1.25 time of the recommended rate for Satuk soil series (16 kg K2O/rai), of potassium fertilizer addition. Result showed that the application of rice husk ash at the rate of 2 ton/rai highly significantly gave the highest fresh tuber yield and starch yield of 4.69 and 1.01 ton/rai, respectively. The application of potassium fertilizer at the rate of 20 kg K2O/rai (1.25 time of recommended rate) significantly promoted the highest fresh tuber yield and starch yield (4.91 and 1.06 ton/rai, respectively) but with no difference to that applied with 0.75 time of recommended rate of which 4.36 and 0.97 ton/rai of respective fresh tuber yield and starch were obtained. For soil properties after growing cassava for one crop, the application of rice husk ash statistically signified higher soil pH, and contents of available phosphorus, iron, manganese and zinc than that of the control with most of them increasing with increasing rate of rice husk ash added. Potassium fertilization also highly significantly increased available potassium content remained in the soil as the application rate increases with the greatest amount of 47.24 mg/kg.