“HABITAT HETEROGENEITY AND ITS IMPACT ON ORGANIC MATTER, NUTRIENT POOL AND NITROGEN MINERALIZATION IN TROPICAL DRY DECIDUOUS FOREST”
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Date
2006
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Indira Gandhi Krishi Vishwavidyalaya, Raipur
Abstract
Study entitled “Habitat Heterogeneity and Its Impact on Organic Matter, Nutrient Pool and N-mineralization in Tropical Dry Deciduous Forest” was conducted during 2005-2006. Two microsite (Depression and non depression) under three habitat (hill base, mid slope, hill top) were under taken for the present study. The soil samples were collected from two microsite along the topographic gradients e.g. hill base, hill slope and hill top in three seasons to quantity organic matter, nutrient pool and nitrogen mineralization.
The major findings of this study are as follows:
Soil pH under three habitats (hill base, mid slope, hill top) ranged between 6.40 and 6.85. The soil texture under the e three habitats was silt loam. Bulk density of soil ranged between 0.70 and 1.25 g cm-3. The organic carbon content in soil was 1.12 to 2.25%. Nutrient pool viz., available P ranged between 10.22 and 24.27 kg ha-1, available K ranged between 203.45 and 367.15 kg ha-1, available N ranged between 132.06 and 273.94 kg ha-1, total N ranged between 0.13 and 0.19 per cent. Mineral N viz., NO3-N ranged from 4.18 to 6.85 µgg-1 while NH4-N ranged between 2.45 and 6.50 µgg-1. The rate of nitrification ranged between 27.48 and 31.39 µgg-1 mo-1. The rate of ammonification ranged between 4.49 and 6.32 µgg-1 mo-1. The value of nitrogen mineralization ranged between 31.97 and 37.71µgg-1 mo-1. Among the three habitats the effect of hill top was greater on physicochemical properties, nutrient pool, nitrification rates and rate of nitrogen mineralization. Study showed marked influence of microsite on all soil parameters studied. Organic carbon content at depression was 1.34 to 2.45 per cent and at non-depression it was 0.91 to 2.06 per cent. Available P was 10.86 to 26.24 kg ha-1 in depression and 9.58 to 22.31 kg ha-1in nondepression. Available K ranged between 213.64 and 384.54 kg ha-1 in depression and 193.27 to 367.15 kg ha-1 in non-depression. Available N at depression ranged between 153.33 and 256.44 kg ha-1 and at non-depression between 110.79 and 219.43 kg ha-1. Total N ranged between 0.13 and 0.20 per cent in depression and between 0.12 and 0.18 per cent in non depression, respectively. Mineral N viz., NO3-N at depression ranged between 4.46 and 7.38 µgg-1 and at non-depression it ranged between 3.90 and 6.33 µgg-1. NH4-N ranged between 3.50 and 6.50 µgg-1 at depression and 2.45 to 5.95 µgg–1 in non-depression, respectively.
The rate of nitrification ranged between 29.68 and 31.78 µgg-1mo-1 at depression and between 25.29 and 31.03 µgg-1mo-1 at non-depression. Ammonification ranged between 4.59 and 6.75 µgg-1mo-1 and between 4.38 and 5.89 µgg-1mo-1, respectively. The rates of nitrogen mineralization at depression it ranged between 34.27 and 38.50 µgg-1mo-1 and between 29.67 and 36.92 µgg-1mo-1 at non-depression.
There was a marked effect of seasonality on organic matter and nutrient pool. Seasonality plays an important role in dry tropical forest. The seasonal value of organic matter at depression ranged between 1.79 and 2.72 per cent and at non-depression it was 1.31 to 2.66 per cent in summer season and in winter it was 1.35 to 2.62 per cent in depression and 0.83 to 2.06 per cent in non-depression microsite. In rainy season it was 0.89 to 2.02 per cent and 0.60 to 1.47 per cent, respectively in depression and non-depression.
Available P at depression ranged between 13.96 and 28.67 kg ha-1 and at non-depression between 11.76 and 24.11 kg ha-1 in summer season. In winter it ranged between 10.23 and 26.16 kg ha-1 and 9.51to 22.23 µg ha-1, respectively in depression and non-depression microsite. In rainy season it was 8.40 to 23.89 kg ha-1 and 7.48 to 20.61 kg ha-1, respectively in depression and non-depression microsite. Available K at depression was 232.64 to 436.64 kg ha-1 and at non-depression it was 205.59 to 373.81 kg ha-1 in summer season. In winter it was 210.78 to 370.68 kg ha-1 and 190.66 to 350.41 kg ha-1, respectively in depression and non-depression microsite. In rainy season it was 197.52 to 346.30 kg ha-1 and 183.56 to 325.02 kg ha-1, respectively in depression and non-depression microsite.
Available N at depression ranged between 199.65 and 31.29 kg ha-1 and at non-depression between 129.61 and 285.37 kg ha-1 in summer. In winter it ranged between 140.91 and 269.69 kg ha-1 and 106.61 to 214.53 kg ha-1, respectively in depression and non-depression microsite. In rainy season it ranged between 119.45 and 181.36 kg ha-1 and 96.16 to 158.36 kg ha-1, respectively in depression and non-depression microsite. Total N at depression ranged between 0.15 and 0.213 per cent and at non-depression from 0.13 to 0.19 per cent in summer. In winter it ranged between 0.13 and 0.21 per cent and 0.11 to 0.19 per cent, respectively in depression and non depression microsite. In rainy season it was 0.10 to 0.18 per cent and 0.07 to 0.10%, respectively in depression and non-depression microsite.
Study revealed the marked influence of habitat microsite on organic matter, nutrient pool and N mineralization in dry tropical forest.
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