SOIL NUTRIENT STATUS OF SUDAN SAVANNA INCEPTISOL (NIGERIA) AMENDED WITH JATROPHA (Jatropha curcas L.) FOLIAGE

Abstract

Evaluation of soil nutrient status is fundamental in sustainable soil nutrient management of an area. In order to
assess the soil nutrient status of the low fertility inceptisols of Nigerian Sudan Savanna amended with foliage of
jatropha, field trials were conducted during the 2018 and 2019 wet seasons at Kadawa, Nigeria (11.650?N and
8.450?E). The treatments included 3 rates of jatropha foliage (0, 5 and 10 t/ha), 3 rates of N-P-K mineral
fertilizer (0, half and full recommended rate) and 2 application methods (incorporation and surface placement).
These were all combined to have 18 treatments replicated 3 times and assigned to plots in a randomized
complete block design (RCBD). Test crop was pearl millet (super sosat variety). Soil and plant samples were
analyzed using standard procedures. Results showed that the soil of the area was loamy sand and of low fertility
status. Incorporation of 10 t/ha jatropha foliage plus half rate of mineral fertilizer increased exchangeable
potassium from 0.16-0.22 Cmol/kg (37.5%). However, Surface application of 10 t/ha of jatropha foliage plus
half rate of mineral fertilizer increased soil organic carbon from 0.34- 0.67% (103%), CEC from 4.7-8.2
Cmol/kg (74.5%), exchangeable calcium from 2.7-5.3 Cmol/kg (96.3%), exchangeable magnesium from 0.71-
1.44 Cmol/kg (102.8%), total nitrogen from 0.026-0.042% (61.6%), available phosphorus from 3.7-9.8 mg/kg
(164.9%), Soil fertility index (SFI) from 12.97-19.71 (52%), soil evaluation factor (SEF) from 7.2-13.9 (93.1),
grain yield from 1275-2991.8kg/ha and 966.7-3842.3kg/ha (134.6-297.7%) while stover yield was increased
from 4791.3-7216kg/ha and 4698-10642kg/ha (50.6-126.7%). Hence, the surface placement of jatropha pruning
at higher rates (? 10 t/ha) plus modest amounts of mineral fertilizer may lead to sustainable management of soils
of the Nigerian Sudan Savanna