TITLE:
Zai Pit Effects on Selected Soil Properties and Cowpea (Vigna unguiculata) Growth and Grain Yield in Two Selected Dryland Regions of Kenya
AUTHORS:
Sillus O. Oduor, Nancy W. Mungai, Seth F. O. Owido
KEYWORDS:
Zai Pits, ASALs, Soil Moisture, Dryland Agriculture, Cattle Manure, Inorganic Nitrogen, Extractable Phosphorus
JOURNAL NAME:
Open Journal of Soil Science,
Vol.11 No.1,
January
27,
2021
ABSTRACT: Erratic
rainfall and temperature regimes, strongly affect agricultural productivity. To
address the reduction in production, this study assessed the effect of Zai pit depths on selected soil properties
and cowpea growth and grain yield. Zai pit technology was tested in two locations falling under Agroecological Zone IV
(relatively dry areas) i.e. Machakos
in Machakos County and Naivasha in Nakuru County, Kenya, aiming to determine the
combined effect of four Zai pit depths
and two levels of manure (plots with manure and plots without manure) on selected
soil properties, growth and yield of cowpea. Experiment was laid out in split plot
arrangement, with manure levels as the main plot factor and Zai pit depths (Flat: Z0, 30 cm: Z30, 45 cm: Z45 and 60
cm: Z60) as subplot factor, replicated four times. Cowpea (M66 variety)
was used as the test crop. Inorganic nitrogen (Nin) and extractable
phosphorus (Pex) were significantly (P ·kg−1 for Nin and 80.4 mg·kg−1 for Pex in Zai pits compared to flat plots which were
at 0.91 mg·kg−1 for Nin and 47.1 mg·kg−1 for Pex.
The values of Nin and Pex also varied depending on depths,
with Z45 having highest Nin at 1.17 against the least, at
0.89 in the Z0, while Pex was highest in Z30 at 102.3 mg·kg−1 while Z0 having the least Pex of 89.7 mg·kg−1.
Generally, crops in Zai pitted plots were larger in diameter (0.46 cm)
and height (34.20 cm) than crops in flat plots at (0.42 cm) and (18.11 cm) diameter
and height respectively. Better performance was observed in yield, with Z45 yielding 853.33 kg·Ha−1 against 685.0 kg·Ha−1 in Flat plots in Machakos while 931.66 kg·Ha−1 in Z45 against 563.33 kg·Ha−1 from Flat plots in Naivasha. This study demonstrated
great potential of Zai pit technology
on crop production, as reflected on improved
growth and yield of cowpeas. Combining Zai pits with manure increases soil Nin, Pex and
is a guarantee of great crop performance in terms of high final yields.