Effect of Cow Dung, Biogas Slurry and Vermicompost on Phosphorus Adsorption Behavior of Soil

Abstract

One of the approaches for phosphorus fertilizer management is controlling the soil phosphorus adsorption behavior. To examine the effect on phosphorus adsorption behavior, three amended soil samples were prepared by mixing 10% (w/w in dry basis) cow dung, biogas slurry and vermicompost with soil. Phosphorus adsorption behavior was examined by using Langmuir, and Temkin adsorption isotherms. Initially, biogas slurry and vermicompost increased the maximum phosphorus adsorption capacity (MPAC) of soil from 461 µg g -1 (control) to 558.0357 and 586.17 µg g -1 respectively, and then decreased steadily and reached 429.92 and 398.41 µg g -1 respectively in five weeks. Whereas in case of cow dung, MPAC was initially decreased, then reached maximum in 17 days and ultimately decreased. Thus application of cow dung along with phosphate fertilizer seems to increase the loss of the fertilizer through runoff and leaching. Conversely, biogas slurry and vermicompost prevent phosphorus loss by regulating phosphorus release through initial enhancement followed by gradual decrease in phosphorus adsorption capacity of soil. Both biogas slurry and vermicompost can be considered as good soil amendments as they have the ability to control the release of phosphorus fertilizer as per the need of the plants.

Effects of Combined Applications of Biogas Slurry and Biochar on Phosphorus Leaching and Fractionations in Lateritic Soil

“…In terms of soilP bioavailability analysis, a similar trend was found in changes of the soil Olsen-P. Specifically, BS200-2 can most significantly (P < 0.05) increase the soil Olsen-P content, which was similar to previous studies [9,29] and can probably be explained by the following two reasons: (i) a higher amount of labile P was used, but less adsorption sites were occupied by the low-molecular-weight organic matter; (ii) biochar alkalinity promoted transformation of the moderately labile P (e.g., Fe/Al bounded P) into labile P. In short, BS can more significantly (P < 0.05) promote the P loss and availability in comparison to the biochar input when the total P inputs are equal (Table 1), and higher BS input showed increasing P-leaching loss and availability. Note: Different letters of the same parameter among the treatments indicate there is significant difference among them (P < 0.05).…”

“…However, soil Pleaching and non-point source pollution can be enhanced [7,8] and made more severe after these organic wastes are applied in soils. Therefore, it is necessary and significant to pay attention to relevant mechanisms of soil P-leaching after these organic wastes are returned to soil [9,10].…”

“…In addition, biogas slurry (BS), being a liquid fraction from anaerobic digestion of organic waste, is often applied to agriculture fields. In China, the annual product of BS is 0.4 billion tonnes [9], and 33% of farmers are using this product as fertilizer [6]. It has been reported that the application of concentrated BS could bring significant changes to tomato production, including increases in organic matter and available N and P [15,16].…”

Cow Urine for Enhancement of Biogas Production and Fertilizer Quality of Biogas Slurry

“…The optimum uptake of most nutrients occurs at a soil pH near neutral. The availability of most macronutrients (nitrogen, phosphorus, potassium, sulfur, calcium, and magnesium) decreases as soil acidity increases [16]. As the pH values of the biogas slurries are near 7.0, they can be considered as good soil amendments.…”