Effect Of Conservation Agriculture On Water Retention, Soil Properties And Maize Yields In Semi-Arid Kajiado County, Kenya

ABSTRACT

Food insecurity and hunger are global challenges attributed to poor crop harvests, land

degradation, low soil moisture and declining soil fertility. Low maize yields and

household food insecurity in Kajiado, Kenya could be alleviated by use of sustainable

agricultural practices such as conservation agriculture (CA), integrated soil fertility

management (ISFM) and increased water use efficiency. This study was carried out in

Kajiado during the long rainy season of March-July, 2016 to (i) determine the effects of

conservation tillage on maize growth and yields (ii) determine the effects of

conservation tillage on soil physical properties (soil moisture retention and soil

structure) and (iii) determine the effect of conservation tillage on soil chemical

properties (Soil Carbon, soil pH, soil N, P, and K). The treatments were laid out in a

RCBD with three replications. The treatments included: 1. Conventional tillage with

residue removal (Control). 2. Conventional tillage with residue retention (3 ton/ha). 3.

Conventional tillage with residue retention (5 ton/ha incorporation). 4. Reduced tillage

– (one plough with 3 ton/ha stover incorporation). 5. Reduced tillage – (one plough with

5 ton/ha stover incorporation). 6. No-tillage practice – (no prior tillage, 3 ton/ha stover

residue chopped, surface applied). 7. No-tillage practice – (no prior tillage, 5 ton/ha

stover residue chopped, surface applied). Analysis was done using SAS version 8.

Results from the study show significant effects (p CT-5>CT-3 >

RT-3 and CTC (Control). At 0-20 cm depth, NT-5 had the highest volumetric soil

moisture content of 0.299m3m-3 which was significantly higher than the other

treatments. NT-5 increased soil moisture by 9.7%, NT3 by 9%, RT5 by 5.4%, while

RT-3 by only 3.8%. After wet sieving, treatments, RT-5, NT-3 and NT-5 significantly

increased the 2-1 mm soil aggregate size, thus indicating improvement in aggregate

stability of the soils. Up to RT-3 does not degrade the soil structure because there was

no significant reduction of the fraction less than 0.5mm. NT-5 significantly gave the

highest stover yields of 5334kg/Ha and grain yields of 3228.2kg/ha which was 37.3%

increase from the control. CT3 had the highest plant height at (12.5cm) 2 weeks after

planting (2WAP). However, NT5 had the highest significant effect (P=0.01) on plant

height 4WAP, 6WAP and 8WAP at 58.2 cm, 122.8 cm and 140.2 cm respectively. No

significant effects (P NT-

3> CT-5 > CT-3 respectively in that order. The treatments had significant effects on soil

mineral N (NH+ and NO-) and total N. On the other hand, the treatments also had

significant effects on available P, Na+, and K+. Therefore, the results confirm that CA is

very effective in enhancing crop yields and improving soil physical and chemical properties.