Cumulative Effect of Cassava Starch Waste and Ground Limestone, and Chemical Fertilizer on Yield and Nutrient Uptake of Cassava Planted in Yasothon Soil Series

Abstract

Cassava planted in sandy soils gives rather low yield due to these soils having low fertility level and being prone to moisture shortage. A cumulative effect of cassava starch waste (CSW) and ground limestone (GL), and chemical fertilizer applied for 7-consecutive-year on yield and NPK uptake of cassava, Huay Bong 80 variety in Yasothon soil series was investigated. This study comprised the 7^th growing season’s results.  The experimental design was arranged in a split plot with four replications. The main plot comprised six treatments of different soil amendments addition while subplot was to compare four rates of NPK chemical fertilizer. Results revealed that the addition of CSW and GL at 6.25 and 1.25 t/ha with 100:50:100 kg N:P₂O₅:K₂O/ha fertilization, a recommended rate, interactively promoted the significantly highest fresh tuber yield and starch yield of 29.22 and 6.92 t/ha, respectively. This highest fresh tuber yield was 78.4% and 114.9% greater than that obtained from the non-amended plot throughout 7-year trial but received NPK chemical fertilizer at the recommended rate and no NPK fertilizer, respectively. The total uptake in cassava showed that the plant took up N in the highest amount followed by K while P was taken up in a very small proportion when compared to the other two nutrients.  Cassava accumulated rather excessive N in leaf and branch whereas N and K uptakes in tuber were slightly too low. Therefore, growing cassava in sandy soils the annual application of CSW mixed with GL at the rate of 6.25 and 12.5 t/ha is necessary to maintain cassava’s yield level.