TITLE:
Assessment of Super Absorbent Polymer (SAP) on Plant Available Water (PAW) in Dry Lands
AUTHORS:
Vincent Ng’eno, Christian Omuto, Duncan Mbuge, Vitalis Too
KEYWORDS:
Plant Available Water (PAW), Soil Water Retention Curve (SWRC), Soil, Super Absorbent Polymer (SAP)
JOURNAL NAME:
Engineering,
Vol.15 No.2,
February
17,
2023
ABSTRACT: One of the ways of overcoming the cost of irrigation
is through in-situ water harvesting at the plant roots. Super absorbent
polymer (SAP) can facilitate water harvesting at the plant roots. This study
attempted to assess the effect of SAP on plant available water (PAW) of
different soils. In this study, SAP was sequentially added at the rate of 0.2%,
0.3% and 0.5% of the soil weight and its impact assessed in clay, sandy clay
and sandy loam soils. The moisture retention characteristics of the original
and SAP treated soils were studied using soil water retention curves (SWRC)
and results modelled using Gardner model. PAW was estimated from SWRC as the
difference between moisture content at 1.5 and 3 bar
in all soils. The difference in PAW between original and treated soils was
assessed at 5% level of significance. The WRC of all the samples was adequately
found to be described by the Gardner model (Coefficient of determination R2 ≥ 98% and residual standard error (RSE) ≤ 0.04). SWRC changed with increase in
SAP percentage in clay, sandy clay and sandy loam soils. Clay had a higher
change in water retention then sandy clay and lastly sandy loam. Plant
available water content (PAW) in all soils increased. In clay soil it increased
with increase in SAP from 0.3291 at zero SAP to 0.6223 at 0.5% SAP. Sandy clay
soil increased in PAW from 0.2721 at zero SAP to 0.5335 at 0.5% SAP and Sandy
loam soils from 0.1691 at zero SAP to 0.3461 at 0.5% SAP. Hence, from the study
SAP can be used to conserve irrigation water in the plant roots and therefore
reducing the cost since PAW has been increased.