Evaluation of soil fertility status under different spacings of eucalyptus tereticornis based agroforestry system
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Date
2018
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CCSHAU
Abstract
The present investigation entitled Evaluation of soil fertility status under different spacings of
Eucalyptus tereticornis based agroforestry system at Research Farm of Forestry Department, CCS
Haryana Agricultural University, Hisar during 2016-17 to evaluate soil physical, chemical and
biological properties and to study the nutrients status in leaf litter fall at different spacing of Eucalyptus
tereticornis based agroforestry system. Soil samples from different spacings of Eucalyptus plantings
viz. 17×1×1 m, 6×1.5 m and 3×3 m were analyzed for different soil properties at 0-15, 15-30, 30-60
and 60-90 cm depth. Soil bulk density and infiltration rate improved in agroforestry system. There was
less effect of different spacings of Eucalyptus trees on soil pH, however electrical conductivity
decreased with decrease in spacing between Eucalyptus trees at different depths. Organic matter and
availability of nutrients (N, P, K, DTPA extractable micronutrients, dissolved organic carbon and total
N) increase significantly at closer spacing (3×3 m) of Eucalyptus tereticornis based agroforestry
system. Improvement in soil properties under agroforestry was more as compared to sole cropping
system. Depth-wise similar trend was observed under different treatment combinations. However the
reduction was more in 15-30 cm soil depth. Available N, P, and K content were in the range 102.0-
121.6, 8.3-10.3, and 244.6-278.2 kg/ha respectively. The DTPA extractable micronutrient Zn, Fe, Mn
and Cu were in the range 0.8- 1.3, 5.1- 6.7, 6.8- 8.1 and 2.6- 3.1 mg/kg respectively. The percent
mineralization rate of nitrogen was in the range 2.5-4.8 %. Mineralization increased significantly by
incorporating trees with crops. The microbial biomass C and urease activity increased from 146.7 to
276.1 mg/kg soil and 45.5 to 64.4 g NH4
+-N/g/h respectively.The dehydrogenase and phosphatase
activity increased from 88.6 to 183.5 mg TPF/kg soil/24 h and 70.8 to 124.7 mg PNP/kg soil/h
respectively. The enzymatic activities were found higest under 3×3 m and these decreased significantly
with increase in tree spacing of Eucalypus and devoid of tree treatment. Leaf liter, nutrient content and
nutrient addition was found maxium under closer spacing (3×3 m) of agroforestry system. The closer
spacing of Eucalyptus returned substantial amount of N (107.4 kg/ha/year) while the average annual
input of N, P and K were 95.6, 12.9 and 17.6 kg/ha/year, respectively. The input of Ca and Mg ranged
from 96.8 (17×1×1m) to 122.9 (3×3 m) and from 50.4 (17×1×1m) to 63.3 (3×3 m) kg/ha/year,
respectively. The total mean micronutrients (Zn, Mn Cu and Fe) return through leaf litter was 6.0
kg/ha/year out of which maximum contributon was of Mn (45%). Therefore, Eucalyptus based
agroforestry system improves soil health by enhanced soil organic matter and improved soil properties.
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