EFFECT OF CONSERVATION AGRICULTURE ON SELECTED SOIL PROPERTIES, MAIZE AND BEANS PERFORMANCE IN WESTERN KENYA AND EASTERN UGANDA

Abstract

Despite Conservation Agriculture (CA) being advantageous towards improving soil quality and thus productivity, farmers in Western Kenya and Eastern Uganda still practice conventional tillage (CT). These result into soil quality decline, impacting negatively on soil chemical, biological and physical aspect. This has led to reduced food production hence increased food insecurity. Objectives of the study were to investigate effects of CA tillage systems (no-till, minimum till) and cropping systems on; i) soil chemical properties, ii) earthworms population, and iii) the economical CA production system; in Bungoma, Trans-Nzoia counties in western Kenya, and Tororo, Kapchorwa districts in Eastern Uganda. This was laid out in 2011 and 2012 cropping seasons. Treatments were tillage [Minimum (MT), No-Till (NT) and conventional (CT)], N-application and cropping systems in a split-split arrangement in a RCBD in 2011-2012. Main plots were tillage systems, nitrogen application [+N and -N] sub plots, and cropping systems [Current practice (CP), Rotation 1(ROT1) and Rotation 2 (ROT2)] as sub-sub-plots. Rotation 1 (ROT1) involved maize-beans intercrop with mucuna relayed after beans harvest. In ROT2, maize, beans and mucuna were planted in strips rotated every season. The strips comprised of 4 rows of maize, 8 rows beans and 6 rows of mucuna. CP was continuous maize-beans intercrop. Test crops were maize and beans, mucuna were a cover crop. Phosphorus and nitrogen was added as DAP and CAN with maize monocrop receiving 26kg P/ha and 30kg starter N/ha, while beans monocrop received 40kg P/ha. Additional 30kg N/ha was added as a split-split plot in a 5m by 10m area (+N). Soil chemical analysis- pH, P, soil organic carbon (SOC), total and mineral nitrogen- was done at each crop harvest. Earthworm population count was done at vegetative stage. Results indicate a significant (p≤0.05) increase in soil pH, available phosphorus, SOC, mineral and total nitrogen from MT, ROT2 and +N interaction. Earthworms increased under MT having mucuna due to minimum soil disturbance and more organic matter providing more food. In Bungoma, Trans-Nzoia, Tororo and Kapchorwa, the highest recorded means of maize yield were: 2.17 (Table 4.22.2), 3.26 (Table 4.23), 2.67 (Table 4.24.2) and 3.80 (Table 4.25) t/ha respectively in 2012. This were significantly (p≤0.05) higher from the initial mean of 1.44 (Table 4.22.1), 1.60 (Table 4.23), 1.93 (Table 4.24.1) and 1.36 t/ha (Table 4.25) respectively in 2011. There was a significant increase (p≤0.01) in beans yields from 0.14t/ha in 2011 to 0.29t/ha (Table 4.26.2): 0.54t/ha (Table 4.27), 1.35t/ha (Table 4.28.2) and 0.30t/ha (Table 4.29) in Bungoma, Trans-Nzoia, Tororo and Kapchorwa respectively. MT, ROT2 and +N interaction was most profitable treatment in all sites.