Soil test and nitrogen, phosphorus and potassium requirement of maize in south western _Nigeria
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Date
1985
Authors
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Publisher
Obafemi Awolowo University, Ile Ife, Nigeria
Abstract
Soil testing as a fertilizer advisory service to farmers is not common in Nigeria. Method of
sample treatment and time of sampling in relation to fertilizer treatment need to be properly
established. In order to shorten the time required for analysis, a multi-element extractant has to
be developed to cover more than one element at a shaking time.
This study was undertaken to evaluate suitable and rapid methods for a soil testing programme.
Simultaneous extraction of P and K at a shaking time of 5 minutes was carried out. Bray II was
recommended for the simultaneous extraction of P and K. The field trial was conducted at five
locations viz: Ikenne, Akure, Agbede, Ilorin and Ilora.
Available nitrogen, NO3-N was the best index of N availability in soil for short period of four
weeks but the poorest under continuous cropping. Soil N critical levels were established with
deficient values of 20 ppm NO3-N, 0.05% total N and 0.7% carbon while the critical values were
30 ppm NO3-N, 0.11% total. N and 1.26% carbon. Field correlation and calibration studies was
used to establish soil critical P and K. Maize responded to N fertilizer at Ilorin, a savanna zone
up to 150 Kg N/ha but lower response to N was observed in forest zone. The critical soil P levels
at about 90% relative yield in the field and glasshouse were 9.5 and 12 ppm P while the
corresponding deficient levels at 50% relative yield were 6 and 7.5 ppm P respectively. The
critical soil K by Bray I, Bray II and NH4 0AC in the field study was higher than greenhouse
value with a range of 0.33 - 0.38 me K/100g. The critical N, P and K concentration in maize leaf.
The tissue at four and eight weeks stage were compared. The relation-ship between the tissue
content at four weeks and relative yield was better than at eight weeks while the critical values
were 3.2%, 0.4% and 3.9% N, P and K at four weeks respectively and 2.80%, 0.29% and 2.50%
N, P and K for eight weeks respectively
Description
194p
Keywords
Fertilizer, Soil test, Extraction, Tissue testing