Cumulative effect of perlite and chicken manure on NPK fertilization for cassava planted in Arenic Haplustult soil: Case study of continuous application for 8 yr

Abstract

Importance of the work: Long-term field trials are vital for sustainable improvement of cassava production in low-fertility sandy soils in northeast Thailand.
Objectives: To investigate the response of cassava to NPK fertilization and some soil properties following the application of perlite (PL) and chicken manure (CM) for 8 yr.
Materials & Methods: The 8 yr field experiment was carried out in an Arenic Haplustult soil, using a split plot design with the main plots comprising no application of soil amendment, compared to the addition of PL at 0.625 t/ha, CM at 3.125 t/ha or PL+CM at 0.625+6.125 t/ha and the subplots consisting of four rates of NPK fertilizer.
Results: After the 8^th growing season, the significantly highest fresh cassava tuber yield (37.54 t/ha) was from the application of a ratio of N-to-P₂O₅-to-K₂O ratio fertilization (100:50:100 kg/ha, respectively) in the PL+CM amended plot. This amount was 64.7% and 220.3% greater than those obtained from the non-amended plot with the same NPK fertilizer added and without NPK fertilization, respectively. The continuous application of CM or the PL+CM mixture significantly increased almost all plant nutrients, pH and organic matter contents in both the topsoil and underlying subsoil compared to no soil amendment.
Main finding: The proper NPK fertilizer rates increased the cassava yield when the soil was continuously amended using modest amounts of PL, CM or PL+CM for several years. Furthermore, these soil amendments, which are recommended for use, improved the quality of the tropical upland sandy soil.