Horizon-wise distribution of primary nutrients’ forms in cultivated soils of mid hills sub-humid zone of Himachal Pradesh
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Date
2021-09-30
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Palampur
Abstract
The knowledge of horizon-wise distribution of primary nutrient forms in cultivated soils is
always required to develop nutrient management strategies for sustainable agro-ecosystems. In the
present investigation, twenty soil profiles representing major soil orders (Alfisols, Inceptisols &
Entisol) under different land use types (maize-wheat, paddy-wheat, vegetable, tea plantation and
orchards) were dug out during 2020-21 for studying different forms of N, P and K and their
relationship with soil properties. To fulfill the objectives of the investigation, horizon-wise soil samples
collected, were analyzed for important soil properties and different forms of primary nutrients. The
soils studied were coarse to fine loamy, strongly to slightly acidic and low to high in organic carbon.
Mean organic N, fixed-NH4
+
-N, exch-NH4
+
-N, NO3
-
+NO2
-
-N, inorganic N, total N and
available N were 829.3, 9.8, 13.2, 9, 32.9, 862.2 & 165.8 mg/kg in surface horizon and 391, 7, 5.4, 3.2,
15, 405.7 and 74 mg/kg in sub-surface horizons, respectively. Organic N, fixed-NH4
+
-N, exch-NH4
+
-N,
NO3
-
+NO2
-_N & available N accounted 96.2, 1.4, 1.4, 1 & 18.7 per cent of total N, respectively.
Concentration of N forms decreased with depth in all the profiles due to decreasing trend of OC content
in sub-surface horizons. N forms positively correlated among themselves and with organic carbon,
CEC, exchangeable acidity, EC, silt & clay contents. On an average, mean value of organic P, saloid P,
active P, inactive P, total P and available P were 211.8, 14.6, 58.5, 169.8, 454.7 & 8.1 mg/kg in surface
horizon and 108, 8.4, 59.5, 190, 364 & 4 mg/kg in sub-surface horizons, respectively. Organic P, saloid
P, active P, inactive P & available P accounted 35.3, 2.6, 15.1, 47 & 1.3 per cent of total P,
respectively. Organic P, saloid P, total P & available P content follows decreasing trend down the
horizon, while active & inactive P forms content follows increasing trend. Organic carbon, CEC,
exchangeable acidity, EC, silt & clay contents of soils positively correlated with all forms of P. The
mean value of water soluble-K, exch-K, non-exch-K, mineral K, total K and available K were 16.3,
63.3, 611.7, 15808.9, 16500.4 & 79.7 mg/kg in surface soils and 14.1, 68, 638.6, 15956.7, 16716 &
81.6 mg/kg in sub-surface horizons, respectively. There was irregular trend in depth wise distribution of
K forms. Water soluble K, exchangeable K, non-exchangeable K, mineral K and available K accounted
0.1, 0.5, 3.8, 95.6 & 0.5 per cent of total K in cultivated soils. All the forms of K were positively
correlated among themselves and with organic carbon, CEC, exchangeable acidity, EC, silt & clay
contents. Distribution of primary nutrient forms in soil is governed by the operational intensity of
pedological factors and land use management practices.
On the basis of simple and multiple correlation coefficients, organic carbon proved better
predictor of all N forms except in fixed-NH4
+
-N where it was clay content. Both clay and organic
carbon proved useful indicator for P forms distribution and also clay content of soil proved better
predictor of all K forms except in water soluble-K, where it was CEC alone.