Effect of Physico-Chemical Properties of Soil on Available Soil Nutrients in Apple Orchards of District Kulgam

Available nutrient status and their correlation with the physico-chemical properties is an important indicator of soil health and plant nutrition. To comprehend the nutrient status in relation to soil properties in apple orchards a study was conducted in temperate Kashmir Himalayas. We analyzed soil samples from major apple growing areas of South District Kulgam for various physio-chemical properties and available nutrient status of nitrogen, phosphorus, potassium, calcium and magnesium. The soils varied from silty clay loam to loam in texture with pH and organic carbon ranging from 4.97 to 6.24 and 1.52% to 2.78% respectively. The available N, P, K, Ca and Mg ranged from 152.32 to 428.62, 9.85 to 24.39, 206.86 to 464.92, 209.78 to 501.12, 509.43 to 621.23 Kg ha-1 respectively. Almost all samples were found to be in low to medium range in pH and electrical conductivity indicating soils are slightly alkaline and non-saline in nature. Current World Environment Journal Website: www.cwejournal.org ISSN: 0973-4929, Vol. 13, No. (2) 2018, Pg. 270-276

Environ., Vol.13(2) 270-276 (2018)   The soil health and soil quality concept has developed systematically with an enhancement in the discernment of soils and soil quality attributes 4,5 .Nutrient concentration in soil and availability to plants are appraised by the minerals present, soil forming factors and management practices 6,7 .
Many authors have evaluated the available nutrient content of soils and their relationship with various physico-chemical properties of soils like pH 8 , EC 9 , OC 10 , bulk density 11 , soil texture 12 and porosity 11 .Management and cultural practices also play an important role in improving the nutrient use efficiency and sustaining the soil fertility by lowering nutrient losses, maintaining or increasing nutrient storage capacity, promoting recycling of plant-soil nutrients, applying fertilizers as additional nutrients in appropriate amounts 3 .So regular testing of soil nutrients and factors having a profound effect on their availability is of utmost importance in achieving the sustainable production levels and soil health.
The fruit productivity and quality of an apple tree, the most important horticultural crop in Jammu and Kashmir state of India, depends on various biotic and abiotic factors: such as soil and climatic conditions that affect processes of plant nutrition depending on the level of soil nutrient capacity and irrigation supply, rootstock vigor and variety combination cultivated, and cultural and management factors viz., soil management (pre-planting, post-planting, fertilization, tillage, irrigation) and crop husbandry (training , pruning, thinning, nutrition, disease and pest management, etc.) 8 .
In case of perennial crops like apple it is an essential practice to maintain higher levels of soil fertility for a longer time to sustain continuous cultivation of fruit crops both under irrigated and rainfed conditions while taking into account the existing horticultural facilities 13,14 .Keeping this in background a study was conducted in the apple orchards of South District of Kulgam, Jammu and Kashmir with the following objectives; (a) to evaluate the nutrient status and physico-chemical properties of soils and (b) to assess the correlation between the available nutrients and physico-chemical properties of soil of apple orchards.

Study Area
The study was carried out in district Kulgam of the state of Jammu and Kashmir, India.District Kulgam is located at 33 0 .65'North latitude & 75 0 .02'East longitude and is situated on the southern side of Jammu & Kashmir State of India.It has an average elevation of 1739 meters.The region falls under the cold humid zone with soils ranging from clay loam to sandy loam in texture and alluvial in origin rich in illite 12 .

Soil Sampling
Soil samples in three replicates from 10 apple growing villages (Mirhama, Ashthal, Chawalgam, Pombay, Kakran, gopalpora, Nillow, Begam, Modergam and Lirow) of South District Kulgam were collected (Table 1).The soil samples were taken after harvesting the fruit in 2016 within the drip line of the canopy to a depth fertilization zone of 23 cm.These soils were air dried and sieved through 2 mm sieve prior to analysis.The samples were collected from the orchards of 15 years or above age.

Soil Physico-Chemical Properties
The pH and electrical conductivity (EC) were estimated in 1: 2.5 soil water suspension by standard procedures 15 .Particle size distribution was determined by international pipette method 15 .Oxidizable organic carbon was determined by Walkley and Black (1934) method 16 .Available nitrogen was determined by alkaline permanganate method of Subbiah and Asija (1956) 17 , available phosphorus was determined by Bray P1 18 and available potassium by neutral normal ammonium acetate and determined on flame photometer as described by Jackson 15 .The exchangeable calcium and magnesium were determined by versenate titration method after extraction with ammonium acetate solution 15 .

Statistical Analysis
.Similar results were presented by Yogeeshappa 25 .Higher content of available potassium is attributed to presence of illite (K rich clay minerals), higher K fertilizer application and manures The results are supported by the findings of Fida et al., 26 and Patel et al., 27 .
Parent material strongly influence Ca and Mg concentration through mineral weathering and soil formation processes, which subsequently affect the cation exchange capacity and base saturation of exchangeable sites.This is in accordance with Bailey et al., 28 , Hintington et al., 29 , and Kabrick et al., 30 .
The medium and higher availability of Ca and Mg is therefore attributed to parent material as limestone with substantial quantity of dolomite and shale of Triassic age along with illite and chlorite minerals which typically supply base cations like Ca and Mg.Similar observations were recorded by the findings of Dar et al., 31 and Yogeeshappa 25 .

relation between Available Nutrients and Physico-Chemical Properties
Correlation analysis of physico-chemical properties of soil with available nutrients is presented in Table 3.The pH of soils showed significant negative correlation with N (r = -0.70)and P (r = -0.52)and non-significant correlation with available K while pH exhibited significant and positive correlation (r = 0.89 and r = 0.68) with available Ca and Mg respectively.The relation indicates that increase in pH decreases available N which is attributed to volatilization loss of N with the rise in pH while in case of available P, conversion of soluble P to insoluble calcium and magnesium phosphate with rise in pH reduces its availability.Similar results were reported by Khokhar et al., 32 and Patel et al., 27 .The pH does not bear any significant correlation with available K. The increase in availability of Ca and Mg with rise in soil pH is attributed to basic nature of Ca and Mg cation as also reported by Medhe et al., 33 .
The OC showed positive and significant correlation with available N (r = 0.98), P (r = 0.80), but non-significant and negative correlation with Ca (r = -0.71)and Mg (r = -0.63).The significant and positive correlation of OC with available N is attributed to release of mineralizable N from soil organic matter in proportionate amounts and adsorption of NH4 -N by humus complexes in soil 34,35 .Acidulating effect of OC, formation of easily accessible organophosphate complexes, release of phosphorus from organic complexes and reduction in phosphorus fixation by humus due to formation of coatings on iron and aluminum oxides is responsible for significant correlation of available P with OC 36,37 .A significant and positive correlation of soil clay content was observed with available K (r = 0.62), Ca (r = 0.72) and Mg (r = 0.67), while with other nutrients its relationship was nonsignificant.A positive and significant correlation of clay with available calcium and magnesium content was also observed by Dar 12 .

Conclusion
Soil health and fertility are key parameters for sustainable agriculture.Soil testing for available nutrient status and assessment of soil physico-chemical factors affecting their availability is an important tool for managing the nutrient balance and productivity levels in apple orchards.The studied soils have low to medium available nutrient levels ranging from 152.0 to 428.0, 9.0 to 24.0, 206.0 to 464.0, 209.0 to 501.0, 509.0 to 621.0 Kg ha -1 for N, P, K, Ca and Mg respectively.Physico-chemical properties of pH, OC and clay have a profound effect on the availability of soil available nutrients.Proper management of these properties can help in restoring the fertility levels in the soil and their relation can prove beneficial for nutrient recommendation system of apple orchards of Kulgam.