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Nutrient mining status

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  • Besides this, nutrient losses through various means are alarmingly large which are rarely taken into account. 
  • The soil fertility status of Indian soils has declined drastically over the years following the era of green revolution and is marked by a negative balance of 8-10 M. tons between nutrients removed by the crops and those added through manures and fertilizers leading to mining of soil nutrient capital and steady reduction in soil nutrient supplying capacity. 
  • The loss through soil erosion is second to nutrient removal by crops. 
  • About 8 M t of plant nutrients are lost through water erosion of soil (5.3 billion t) while estimates of leaching and gaseous losses are not available. 
  • Even in well managed cropping systems like rice-wheat raised on currently recommended nutrient levels, depletion of soil fertility has been reported .
  • Considering the projected food grain demand and fertilizer consumption by 2010 and 2025, this gap is likely to increase to 11 and 13.3 Mt of NPK, respectively.  
  • The situation is further aggravated by the depletion of major soil nutrients like N and K in intensive cropping systems and emergence of wide spread deficiencies of secondary (S, Ca) and micronutrients (Zn, Fe, Mn, Cu and B). 
  • Soil test data available for major part of the country for the major nutrients (N, P, K) show that 89 and 80% of the soils are low to medium in N and P, and about 50% of the soils are responsive to K supply . District wise soil fertility status of Indian soils also indicates a similar trend .
Table 2: Percentage of soil samples (total 4.54 M) in different categories of nutrient availability
Nutrient

Low

Medium

High

Nutrient Index

Nitrogen

63.1

25.6

11.3

1.48

Phosphorous

42.3

37.7

20.0

1.78

Potassium

12.9

36.7

50.4

2.37
       <1.67 index and >2.33 refer to low and high status.

Table 3: Generalized available N, P and K status in Indian soils
Nutrient

Districts surveyed

Districts having available nutrient status of

Low

Medium

High

N

364

228

118

18

P

360

170

184

17

K

361

47

192

122


File Courtesy: 
Brajendra and Vijai Pal Bhadana Directorate of Rice Research, Hyderabad - Published in Rice Knowledge Management for Food and Nutritional Food Security
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