Abstract
Intensive land-use change, the overgrazing of pastures, and the poor soil management in the Amazon region induce significant soil chemical degradation, causing alterations in the soil phosphorus (P) dynamics. Here, we studied the changes in P fractions and availability throughout the soil profile along a chronosequence composed of four study areas representing the typical land-use transition from forest to pasture for extensive cattle ranching in the Colombian Amazon region: (i) Forest—Deforested—Pasture 4 years old and Pasture established >25 years after deforestation. Soil samples collected at 0–10, 10–20, 20–30, and 30–40 cm depth were used for the sequential fractionation of P, determination of acid phosphatase activity and soil organic carbon (C) content, and calculation of C:organic P (Po) ratio and P stocks. Our results showed that the land-use change caused a decrease of 31.1% in the fractions of labile inorganic P, with the mineralization of organic P by phosphatase enzyme playing an essential role in the P availability. Although according to the C:Po ratio of the deeper layer the P seems to be sufficient to satisfy the plant needs of all the land uses assessed, the exploitation of soil nutrients in pastures reduced by 6.1% the moderately and non-labile P stock. Given the role of cattle ranching in the economy of tropical countries, it is imperative to adopt strategies of soil P management to improve P-use efficiency, avoiding the degradation of grazing land resources while ensuring the long-term sustainability of rangeland livestock and decrease further deforestation of the Amazon rainforest.
Highlights
Introduction iationsThe Amazon forest is the largest tropical forest in the world and plays a valuable role in global carbon flow and the water cycle [1,2]
The first two components explained to land use (Figure 2b) (p < 0.001; 25% of explained variance), indicating that the distribuof the variance, with fractions grouped into two clusters clearly defined according to land tion of P in the forest and deforested areas was more similar to each other, with higher use (Figure of explained variance), indicating that the distribution of P
The results evidenced the low soil P availability typically found in tropical soils of low natural fertility, with a considerable proportion of P in the less labile pools
Summary
The Amazon forest is the largest tropical forest in the world and plays a valuable role in global carbon flow and the water cycle [1,2]. The land-use change process, overgrazing of pastures, and the poor soil management practiced by the farmers in the Colombian Amazon induce significant soil degradation, leading to unproductive pastures over time. Alterations in the soil nutrient dynamics [5,6,7]. Possibly in the cycling of phosphorus (P) [8], one of the most limiting elements for plant growth [9,10], are related to the soil chemical degradation in this region.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
