GENESIS, CLASSIFICATION AND EVALUATION OF SOILS IN PAKALA MANDAL OF CHITTOOR DISTRICT, ANDHRA PRADESH
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Date
2015
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Acharya N.G. Ranga Agricultural University, Guntur
Abstract
The present investigation involves study of genesis, classification and evaluation of soils in Pakala mandal of Chittoor district, Andhra Pradesh. For this, seven representative pedons were selected in seven different locations of the study area covering all types of soils. All the seven pedons were described for their morphological features in the field and horizon-wise samples were collected and analyzed in the laboratory for physical, physico-chemical and chemical properties.
The study area was characterized by semi-arid monsoonic climate with distinct summer, winter and rainy seasons. The pedons selected were located on plains (0-1%), very gently sloping (1-3%) and gently sloping (3-5%) topography. All the Pedons were developed from granite-gneiss parent material
The morphological features indicated the presence of AC (Pedons 1, 2 and 6) and ABC (Pedons 3, 4, 5 and 7) profiles. The soils were shallow to very deep in depth, brown to dark greyish brown in colour, sandy clay loam to clay loam in texture and had crumb, sub-angular blocky and angular blocky structure.
The clay content decreased with depth in pedons 3 and 6 whereas pedons 1, 2, 4, 5 and 7 had shown no specific trend with depth. Physical constants like water holding capacity, loss on ignition and volume expansion
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followed the trend of clay content. The bulk density increased with depth in pedons 1, 2, 4 and 6 while the remaining pedons showed an irregular trend of bulk density with depth.
The soils were neutral to slightly alkaline in reaction, non-saline and low to medium in organic carbon. All the pedons registered low to medium CaCO3 status. CEC values were low to medium and exchange complex was dominated by Ca+2 followed by Mg+2, K+ and Na+. Chemical composition of soils revealed that all the pedons had high silica content indicating siliceous nature. Regarding nutrient status, the soils were low in available nitrogen, low to high in available phosphorus, low to medium in available potassium and deficient to sufficient in available sulphur. However, soils were deficient to sufficient in available zinc, deficient in iron and sufficient in available copper and manganese.
Based on morphological, physical, physico-chemical, mineralogical and meteorological data, the soils of Pakala mandal were classified as:
Pedons 1 & 6 : Fine-loamy, siliceous, isohyperthermic, Typic Ustorthent Pedon 2 : Fine-loamy, siliceous, isohyperthermic, Typic Ustifluvent Pedon 3 & 7 : Fine-loamy, smectitic, isohyperthermic, Typic Haplustept Pedon 4 & 5 : Fine-loamy, mixed, isohyperthermic, Typic Haplustept
Based on the soil properties, the soils of the Pakala mandal have been classified into land capability classes and sub-classes viz., IIIse (Pedons 2, 4 and 7), IIIs (Pedons 3 and 5), IVse (Pedon 1) and IVsw (Pedon 6).
The soil-site suitability evaluation of study area revealed that pedons 3 and 4 were highly suitable (S1) for sorghum and sugarcane and moderately suitable (S2) for groundnut. Pedon 4 was moderately suitable (S2) for rice and pigeonpea. Pedons 5 and 7 were moderately suitable (S2) for sugarcane and pedon 5 was moderately suitable (S2) and pedon 7 was highly suitable (S1) for growing of sorghum crop. Pedon 7 was highly suitable (S1) and pedon 5 was moderately suitable (S2) for growing of rice, groundnut and pigeonpea crops. Pedon 3 was marginally suitable (S3) for growing crops like rice and pigeonpea.
Pedon 1 was highly suitable (S2) for rice and sorghum, moderately (S2) suitable for sugarcane and marginally suitable (S3) for groundnut and pigeonpea. However, pedon 6 was highly suitable (S2) for rice, sugarcane and groundnut, moderately suitable (S2) for sorghum and marginally suitable (S3) for pigeonpea. Pedon 2 was highly suitable (S1) for sorghum, moderately suitable (S2) for rice, groundnut and pigeonpea and marginally suitable (S3) for sugarcane.
Description
D5152
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