Effects of Harvesting Times and Fertilizer Application on Cassava Yield and Quality in Rainforest and Guinea Savanna Agroecological Zones of Nigeria

Abstract

Farmers desire to harvest cassava roots with high total dry matter and of good quality at shorter times. However, they have limited knowledge regarding combinations of improved varieties and right types and rates of fertilizer application that are most suitable for their agro ecological zones. The study was carried out to quantify total dry matter and root quality response of six cassava varieties to fertilizer application and intra-annual rainfall variability in two agro-ecological zones of Nigeria. Two field experiments were conducted at Oke-oyi and Ikenne. Three inorganic NPK fertilizer types were applied at two rates to six cassava varieties in a split split plot arrangement with three replicates. In each experiment cassava was harvested destructively at 6, 8, 10 and 12 MAP. Data on yield and quality parameters were analyzed using SAS, means separation by LSD 5%. The results revealed that fertilizer application significantly increased all the parameters measured at Ikenne (at both experimental sites) except fresh storage root weight and dry matter content at Oke-oyi. TME 419 had higher starch content at Ikenne while TMS 96/1632 had significant higher starch content at Oke-oyi. Cyanide potential was highest in TMS 96/1632 and TMS 30572 at 12 MAP at Oke-oyi and Ikenne respectively. NPK 12-12-17 was observed to perform better than other fertilizer types. This study showed that application of NPK 12-12-17 fertilizer at 300 kg ha-1 to cassava varieties TME 419 and TMS 98/0505 at study sites, increased total dry matter root yield, starch content and showed low cyanide potential. Farmers who plant these two cassava varieties either for food or for industrial purposes at the two sites will earn higher income.