Study into tillage-mulch package for production of sweet potato (Ipomoea batatas L) effect on soil properties and yield

Field experiments were carried out during 2014 cropping season at Omuo-Ekiti and Kabba. Omuo falls within the forest zone while Kabba is in the southern guinea savanna zone of Nigeria. The experiment at the two sites was to study the effect of tillage and mulch combinations on soil physical and chemical properties and sweet potato (Ipomoea batatas L.) performance. The trial consisted of 2 x 5 factorial combinations of two tillage methods: no-tillage (NT) and manual tillage (MT) and five levels of mulch, siam weed (Chromolaena odorata), {0, 5, 10, 15 and 20 t/ha}.These were laid out using split plots design arranged in a randomized complete block with each treatment replicated four times. There were no significant differences in the values of soil moisture content, soil temperature, porosity and bulk density between Omuo and Kabba sites. Omuo site has significant values of soil organic matter (SOM), total N, K and sweet potato tuber yield compared with Kabba site. Omuo has 1.8 t/ha (10%) higher sweet potato yield compared with Kabba. No-tillage treatment has higher soil moisture content, SOM, N, P, K, Ca, Mg and higher tuber yield compared with manual tillage, The yield difference between NT and MT was 2.9 t/ha (16.7%). Application of mulch increases the yield components of sweet potato compared with no mulch application. The increase in yield as mulch rates increases was adduced to increase in soil organic matter from the mulch. There were however no significant differences between 15 and 20 t/ha mulch levels. Mulch applied at 15 t/ha was found to be suitable for sweet potato in tropical Alfisol. Therefore for soil fertility conservation and performance of sweet potato, no-tillage and 15 t/ha siam weed mulch is recommended