Abstract:
Soil nutrient augmentation by some nitrogen (N2) fixing trees/shrubs coupled with their profuse
litter cannot be over emphasized since most of them are deciduous. Thus, the influence of
Albizia lebbeck Benth (its green manure and N2 fixation activities of its 6 months’ old tree rows
when first planted) on soil fertility under alley cropping (an agro-forestry system) with Irish
potato (Solanum tuberosum L.) was investigated. The experimental design was a randomized
complete block design (RCBD) comprising five treatments (T0 - T4) and three replicates. Soil
sample analyses (pre and post experiment) were done. Tending operations and data collection on
the morphological and yield parameters of the test crop throughout the five cropping seasons
were carried out. Results on the soil physical properties indicated that the nine (9) samples from
the three soil depths of T4 were predominantly sandy loam (except two samples) sequel to the
fact that T4 received the highest rate of green manure application (10 ton ha-1) and also had A.
lebbeck tree rows. Thus, a little (non-significant) difference between the pre and post planting
soil texture was observed and the textural classes were mainly loamy textured with sandy clay
loam, clay loam and sandy loam constituting the dominant textural classes. Regarding the soil
chemical properties, the organic matter and % N2 were very low and the values decreased from
pre planting to after planting (no significant difference between treatments /blocks) due to crop
removal. A. lebbeck green manure and its tree rows significantly (P < 0.5) influenced the
available P and K at three soil depths and block effects were observed at significant level (P <
0.5) on the pH and Mg. The morphological parameters (plant height, leaf count and collar girth)
except stem count were highly influenced by the different levels of Albizia lebbeck green
manure application and its tree rows (sequel to N2 fixation) at P < 0.1 which subsequently
brought about significant differences in yield (tuber count (P < 0.5) and tuber weight (P <
0.01).of the crop (Irish potato) in all the 5 treatments and throughout the 5 cropping seasons
owing to modification / improvement on the soil nutrient status in the agro-forestry farm |
