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DYNAMICS OF MAJOR NUTRIENTS IN A CALCAREOUS VERTIC HAPLUSTEPTS UNDER AICRP-LTFE SOILS

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Title DYNAMICS OF MAJOR NUTRIENTS IN A CALCAREOUS VERTIC HAPLUSTEPTS UNDER AICRP-LTFE SOILS
 
Creator RAJANI ASHOKKUMAR VALLABHBHAI
 
Contributor Golakiya B. A.
 
Subject HAPLUSTEPTS UNDER AICRP-LTFE SOILS
AGRICULTURAL CHEMISTRY
 
Description Most of the research information related to available forms of major nutrients are short-term studies. Cultivating soil for long period of time is changing major nutrient status. Losses of major nutrients are, in fact gradual and sometimes hidden. It is therefore not easy to recognize and understand the physical, chemical and biological processes leading to such major nutrient constraints in sustaining soil health and productivity in major soil cropping system of the sub-agro-ecological zones. Junagadh is one of the centers representing medium black calcareous soil (Vertic haplustepts). These soils are difficult to manage from fertility point of view. In view of the above the following broad objectives were set:
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(1)To know the status of major nutrients (N, P, K, S) fractions in soils under AICRP- LTFE.
(2)To find out the depletion of major nutrients fractions in the soil under investigation.
(3) Modeling the dynamics of major nutrient fractions in LTFE soils.
To achieve the forgoing objectives, this investigation initiated which comprised of samples derived from long term fertilizer experiment started 8 years back on Vertic haplustepts calcareous medium black clayey soils of Junagadh. The samples were subjected to fractionation of major nutrients viz., N, P, K, and S. The major nutrients, their fractions and soil properties were related to various yields and NPKS content from plants. In this part also the data were subjected to correlation analysis, stepwise regression, multiple correlation and path analysis. The LTFE involved twelve treatments including untreated control which was subjected to analysis of variance in order to find out the effect of various treatments on yield, N, P, K, S content and major nutrients fractions and also depletion in a long term cycle of 4 and 8 years.
In a long run, treatment differences in groundnut yield diminished while wheat yield showed significantly higher values in T8 after long spell of 8th year. The treatment T3 registered the highest N content and T8 the lowest in groundnut pod while T2 recorded highest content and T9 the lowest in groundnut haulm. The T8 registered the highest content while control the lowest both in wheat grain and straw. In groundnut pod, phosphorus content decreased while in haulm it increased, likewise in wheat grain phosphorus content was increased but in straw it decreased after a period of 8 years. The content of potash
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after 4th year of cycles showed increase while after 8th year cycle it declined in groundnut and wheat. In groundnut, sulphur content increased after 4th year while it declined after 8th year. In wheat, sulphur content declined after 4th and 8th year.
With respect to forms of nitrogen it can be deduced that there was a decline in soil nitrogen levels. Ammonical-N & nitrate –N status of LTFE soils in general decreased after long run, but it increased in treatment T10 due to fixation of atmospheric nitrogen by Rhizobium bacteria. Whereas Available-N status in treatments which received FYM (T8, T9), marginally increased. Available status of P in LTFE soils was also decreased after long run, but that was also increased in treatments where FYM application was there i. e. T8 &T9. There was overall increase in Inorganic-P & Total-P status, but status of Available-P decreased due to calcareous soil, but due to chelating effect of organic material in treatments T8 &T9 there was increase in the availability of phosphorus after long run in the LTFE soils. The application of FYM also maintained or increased potassium status of LTFE soils. In treatments of FYM (T8, T9), the status of potassium fractions increased. In case of sulphur status of LTFE soils, FYM also played a vital role. It maintained availability of sulphur in soils, but more increment after a long run was observed in T11, where P source was SSP which contains 13 % S.
The Available form of nitrogen was found in maximum proportion. At initial stage Ca-P fraction was predominant but after long run picture was changed and maximum proportion was recorded as a Reductant soluble-P. Whereas HNO3 soluble-K was recorded the highest in proportion among different forms of potassium and
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maximum proportion among sulphur forms was as Non-sulphate & Organic forms of sulphur.
Correlations:
The Available-N exhibited positive relationship with Nitrate-N & Ammonical-N. Available-P ascribed significant positive relationship with Inorganic-P, Saloid bound-P, reductant-P & Occluded-P. Available-K form of potassium depicted significant positive relationship with all other forms of potassium, while Heat soluble-S form revealed significant positive relationship only with water soluble-S fraction of sulphur.
The Available-N and Ammonical-N forms of nitrogen ascribed positive relationship with groundnut yield and negative with wheat yield. Whereas phosphorus forms exhibited positive relationship with wheat yield and negative with groundnut yield. Most of the potassium forms also ascribed positive relationship with groundnut yield, while water soluble-S fraction of sulphur exhibited significant positive relationship with groundnut yield and negative with wheat yield. Available-N exhibited significant positive relationship with P content of pod, K content of haulm, N content of grain & S content of grain and straw. Available-P increased K content of groundnut pod & N, P, K content of wheat straw. Most of the fractions of potassium facilitate N, P, K and S translocation from soil to groundnut and wheat crops. Heat soluble-S also ascribed significant positive relationship with P content in wheat straw.
Available-N form had positive interaction with Ca-P, Available-P, Fe-P and negative with Inorganic-P and it exhibited positive interaction with all fractions of potassium. Available-P also
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revealed positive interaction with all forms of potassium. Available-K ascribed significant positive interaction only with water soluble-S.
Available-N and Available-K ascribed significant positive relationship with soil pH & negative with soil EC. Whereas Available-P and Available-S exhibited negative relationship with soil pH & positive with soil EC.
The available forms of major nutrients influenced by other forms were subjected to stepwise regression and multiple correlation and regression analysis. The prediction models were based on multiple correlation and regression analysis over a cycle of 1, 4 and 8 years. Total-N & Nitrate-N forms influenced on Available-N to maximum extent. The Fe-P influenced maximum on available-P. All forms of K influenced on available-K at some extent and Sulphate-S had maximum impact on Heat soluble-S. Soil pH had more impact on available N, P, K & S than soil EC.
Path co-efficient:
The Nitrate-N & Ammonical-N forms ascribed maximum direct positive effect on Available-N. Saloid-P exhibited maximum direct positive effect on Available-P. Whereas HNO3 soluble-K ascribed maximum direct & indirect positive effect on Available-K. Total-S exhibited maximum direct effect on Heat soluble-S.
It has been deduced from the results, that the crop available forms of major nutrients viz. nitrogen, phosphorus, potassium & sulphur ascribed depletion over time irrespective of fertilizer treatments, except in treatments which received FYM along with inorganic fertilizers. Application of FYM not only sustains fertility, but also increases soil fertility status as like here in P2O5 status of the LTFE soil in treatment which received FYM, increased available-P status in
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LTFE soil from low category to high category. The combined application of FYM and inorganic fertilizers in continuous manner, have sustained the crop yield. The dynamics of major nutrients along with its forms exhibited both trend, negative & positive with varying magnitude according to the soil. The total form in case of N, the Fe-P form in case of P, most of the forms in case of K and sulphate-S forms in case of S had the maximum influence on available forms of major nutrients.
 
Date 2016-09-21T09:38:41Z
2016-09-21T09:38:41Z
2009-01
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/77885
 
Language en
 
Format application/pdf