Developing soil testing protocol for potentially available phosphorous in acidic soils under organic production system /
Patgiri, Pritisha
Developing soil testing protocol for potentially available phosphorous in acidic soils under organic production system / Pritisha Patgiri. - Umiam ; CPGS-AS, CAU, October 2021. - viii, 92p. : ill., some col. ; 30 cm. - [ Soil Science and Agricultural Chemistry, School of Natural Resource Management ] .
The dynamic fraction of phosphorus (P) which is considered in conventional soil testing cannot explain the correct status of P in soils under organic production systems as the conventional soil testing protocols do not take into account the potentially available P pools. A suitable extractant which can extract potentially available P in acidic soils under organic production system is highly required for precise recommendation of P. Therefore, an investigation was carried out to characterize the inorganic P pools and identify the most suitable extractant to assess such inorganic P pools which, in turn, aided in developing a soil testing protocol for potentially available phosphorus. Under this investigation, 40 random soil samples from two soil orders (Alfisol and Inceptisol) were collected from each of the five selected sites viz. two conventional farms: CPGS-AS research farm, Umiam; a farm of Palwi village, Bhoirymbong block and three organic farms: ICAR organic research farm, Umiam; a farm of Krydem village, Bhoirymbong block and virgin forest farm of CPGS-AS, Krydemkulai. The collected soil samples were well-composited location wise, processed and six composite sub-samples were derived from each location. These soil samples were analyzed for the chemical and biological parameters adopting the standard procedures. The soils were basically acidic with low available P content. Further, five organic acid extractants, i.e., 2% Citric acid extractant; Double Lactate extractant (0.02 M Ca-lactate + 0.05 M Lactic acid at pH 4.1); 2, keto-glutaric acid extractant (0.05 M 2 keto-glutaric acid + 0.02 M HCl at pH 4.0); Acetic acid extractant (0.54 N Acetic acid + 0.7 N Sodium acetate at pH 4.8) and Lactic acid extractant (0.02 M Ca-lactate + 0.02 M HCl at pH 3.7) were employed to obtain different sizes of potentially available P pools which were compared with the conventional Bray 1 extractant (check extractant). Multiple linear regression models were obtained for each of the extractants taking total P as the dependent variable, organic carbon and the extractants as independent variables. Regression analysis reflected that 2% citric acid and double lactate P along with organic carbon had a strong relationship with that of total P (R2=0.93) which signified that these two extractants could well explain the variation of total P of organic soils. On the other hand, Bray-1 extractant could only reflect a weak relationship between total P, organic carbon and Bray-1 P (R2=0.26). The R2 values obtained from the individual extractants extractable P were 0.78, 0.62, 0.53, 0.57 and 0.59 for citric acid, double lactate, acetic acid, lactic acid and 2, ketoglutaric acid, respectively. Hence, 2% citric acid and double lactate extractants may be proclaimed as the promising extractants which can best estimate the potentially available phosphorus pools in organic farms of Ri-Bhoi district, Meghalaya and for making precise P recommendation, the soil must be tested with these extractants to march towards a successful organic cultivation.
Soils--Analysis.
Soils--Testing.
Acidic Soils--Phosphorous content.
Developing soil testing protocol for potentially available phosphorous in acidic soils under organic production system / Pritisha Patgiri. - Umiam ; CPGS-AS, CAU, October 2021. - viii, 92p. : ill., some col. ; 30 cm. - [ Soil Science and Agricultural Chemistry, School of Natural Resource Management ] .
The dynamic fraction of phosphorus (P) which is considered in conventional soil testing cannot explain the correct status of P in soils under organic production systems as the conventional soil testing protocols do not take into account the potentially available P pools. A suitable extractant which can extract potentially available P in acidic soils under organic production system is highly required for precise recommendation of P. Therefore, an investigation was carried out to characterize the inorganic P pools and identify the most suitable extractant to assess such inorganic P pools which, in turn, aided in developing a soil testing protocol for potentially available phosphorus. Under this investigation, 40 random soil samples from two soil orders (Alfisol and Inceptisol) were collected from each of the five selected sites viz. two conventional farms: CPGS-AS research farm, Umiam; a farm of Palwi village, Bhoirymbong block and three organic farms: ICAR organic research farm, Umiam; a farm of Krydem village, Bhoirymbong block and virgin forest farm of CPGS-AS, Krydemkulai. The collected soil samples were well-composited location wise, processed and six composite sub-samples were derived from each location. These soil samples were analyzed for the chemical and biological parameters adopting the standard procedures. The soils were basically acidic with low available P content. Further, five organic acid extractants, i.e., 2% Citric acid extractant; Double Lactate extractant (0.02 M Ca-lactate + 0.05 M Lactic acid at pH 4.1); 2, keto-glutaric acid extractant (0.05 M 2 keto-glutaric acid + 0.02 M HCl at pH 4.0); Acetic acid extractant (0.54 N Acetic acid + 0.7 N Sodium acetate at pH 4.8) and Lactic acid extractant (0.02 M Ca-lactate + 0.02 M HCl at pH 3.7) were employed to obtain different sizes of potentially available P pools which were compared with the conventional Bray 1 extractant (check extractant). Multiple linear regression models were obtained for each of the extractants taking total P as the dependent variable, organic carbon and the extractants as independent variables. Regression analysis reflected that 2% citric acid and double lactate P along with organic carbon had a strong relationship with that of total P (R2=0.93) which signified that these two extractants could well explain the variation of total P of organic soils. On the other hand, Bray-1 extractant could only reflect a weak relationship between total P, organic carbon and Bray-1 P (R2=0.26). The R2 values obtained from the individual extractants extractable P were 0.78, 0.62, 0.53, 0.57 and 0.59 for citric acid, double lactate, acetic acid, lactic acid and 2, ketoglutaric acid, respectively. Hence, 2% citric acid and double lactate extractants may be proclaimed as the promising extractants which can best estimate the potentially available phosphorus pools in organic farms of Ri-Bhoi district, Meghalaya and for making precise P recommendation, the soil must be tested with these extractants to march towards a successful organic cultivation.
Soils--Analysis.
Soils--Testing.
Acidic Soils--Phosphorous content.