The response of cassava to different fertiliser rates in two contrasting agro-ecological zones in Uganda
Kayuki Crammer Kaizzi1, Hilary Semaana Rugema2, Sven Gönster-Jordan3
1National Agricultural Research Organization (NARO), National Agricultural Research Laboratories (NARL) - Soils, Environment and Agrometeorology, Uganda
Cassava is a major staple and food security crop for the rural and urban population in Uganda and an important raw material for industrial production processes. Cassava is considered to grow well on poor soils, to require no external inputs and to be grown as last crop in the rotation, so yields are usually low. To increase yields, cassava specific fertilisers are being developed and validated for different agro-ecological zones in Uganda through response, omission and validation trials. The trials were implemented in April 2021 and first results on cassava response to N, P and K are available. Cassava height was determined after 9 months of growth in 2 contrasting agro-ecological zones (Tororo, Kioga Plains; Lira North Eastern Savannah Grasslands) following application variants of 0 – 100 kg N ha-1, 0 – 60 kg K ha-1 combined with 60 kg N ha-1, 0 – 60 kg K ha-1 combined with 60 kg N and 15 kg P ha-1, and 0 – 30 kg P ha-1 combined with 60 kg N and 24 kg K ha-1. Cassava height was consistently increased with N, P and K application. For the N-only variant, maximum height was 2.02 m in Lira and 1.49 m in Tororo achieved at 80 and 100 kg ha-1, respectively. Application of different K rates together with 15 kg P and 60 kg N ha-1 did not result in significant increase of cassava heights in Lira; however, a significant increase was achieved in Tororo up to 32 kg K ha-1 implying that K is limiting growth after N and P application. Cassava height was significantly increased with rising P application rates in Lira. In Tororo, however, no significant difference in height was observed at rates up to 15 kg P ha-1 and cassava heights even significantly decrease at higher rates likely attributed to other limiting nutrients. Results obtained from measuring plant height indicate that N limits cassava growth across both sites, while K limits in Tororo following N and P application and P in Lira following N and K application. However, forthcoming yield data are needed to confirm these results.
Keywords: Blend formulation, crop specific fertiliser, East Africa, Manihot esculenta Crantz, soil fertility
Contact Address: Sven Gönster-Jordan, K+S Minerals and Agriculture Gmbh, Research & Development Agriculture, Bertha-Von-Suttner-Str. 7, 34131 Kassel, Germany, e-mail: Sven.Goenster-Jordank-plus-s.com