Soil analysis based diagnostic norms for Indian citrus cultivar

Abstract

Absence of thresholds of soil properties is one of the limitations for successful establishment of soil constraint free citrus orchards. The efforts were, therefore, made to develop soil diagnostic criteria, based on statistical models using relationship between soil analyses and fruit yield of Citrus reticulata Blanco, cultivar Nagpur mandarin. Soil properties influencing the fruit quality parameters were also screened. A total of fifty-seven soil profiles, covering a wide range of soil types belonging to soil orders viz., Entisol, Inceptisol, and Vertisol representing different physiographical positions were studied during 1997–2000 under sub-humid tropical climate of central India. The suggested optima for various physico-chemical properties revealed that fruit yield was influenced by soil characteristics up to 15–30 cm depth, with soil–crop response better at 0–15 cm than 15–30 cm depth. Beyond this soil depth, due to poor correlation coefficient values, the yield predictability was very low from established optimum yield. Linear increase in fruit yield with free CaCO3 content up to 12% at 0–15 cm soil depth indicated that soils rich in exchangeable Ca2+ favored the higher yield, buildup of total solids, and reduced titrimetric acidity in juice. The soil properties, clay content, free CaCO3, water soluble, and exchangeable Ca2+, available nitrogen (N), phosphorus (P), and zinc (Zn) correlated significantly with fruit quality parameters viz., juice content, acidity, and total soluble solids.