"The Pike River watershed has a history of phosphorus (P) pollution due to surface and subsurface leaching, and erosion of agricultural soil rich in P. It is therefore important to consider factors that may change the dynamics of P sorption and desorption behaviours and potentially increase the P concentration in the soil solution. This thesis investigates the effect of corn stalk residue presence and application rate on P sorption and desorption. This thesis also investigates the effect of varying solution pH and ionic strength on P release. Batch experiments were used to investigate P sorption followed by experiments to test the reversibility of the sorption process under different corn stalk residue applications (0.3,5.3,10.3,15.3, and 20.3%) and at different P concentrations (0, 12.9, 27.7, 42.2, 57.0, and 71.8 mg L-1). The quantity of P sorbed to soil was found to decrease significantly as residue application rates increased (p

The potential of competitive anion adsorption for phosphate, using silicate and sulfate as a possible management strategy to increase phosphate availability to corn was tested on two extremely acidic, phosphorus deficient soils, Luisiana clay and Adtuyon clay. This study was conducted with the following objectives: a) to evaluate the effects of calcium, magnesium, potassium and sodium silicates on P sorption, available P and dry matter yield of corn. b) to evaluate the effects of calcium, magnesium and sodium sulfate on P sorption,available P and dry matter yield of corn, and c) to evaluate the effects of calcium silicate and calcium sulfate on available P. soil pH, exchangeable aluminum and grain yield of corn. Application of 250 ppm and 500 ppm silicate in the form of calcium silicate on Luisiana clay decreased the P sorption maximum of the soil from 2.4522 to 2.4237 and 2.2969 mg Pg-1, respectively. Other silicate sources had lesses effect than calcium silicate in decreasing the P sorption maximum of the soil. Sulfate application resulted to a very Slight decrease in the P sorption maximum of the soil. On Luisiana clay not fertilized with phosphorus, application of differnt silicate and sulfate compounds did not increase dry matter yield of corn but phosphorus application resulted in significantly higher dry matter yield. Combined application of 150 ppm P and 250 ppm silicate as calcium silicate and potassium silicate significantly increased dry matter yield of corn. On Adtuyon clay, the application of (...).

ABSTRACT: This ageing process was due to a shaking artifact (30%), microbial immobilization (57%), and sorption of P onto the soil in a non-oxalate accessible form (13%). Liming and organic anion loading improved P bioavailability in this Brazilian soil. Long-term ageing and continuous exudation of organic anions also influence P bioavailability. Management options that recognize this will improve bioavailability of native and applied P sources in this important agricultural region of northeastern Brazil.

Agriculture is a crucial component of the economies of many of the countries in transition from a centrally-planned to a market economy and the sector is by no means immune to the environmental and socioeconomic problems confronting the countries as a whole. The concept of sustainable development provides a convenient framework for the formulation of government environmental policy for such countries, especially those of them that aspire to join the EU and would thus be expected to meet EU environmental standards. For agriculture, this inevitably involves appropriate strategies for balancing crop and animal production while protecting the quality of the national soil and water resources. There is thus an urgent need to compile, exchange and evaluate current information on the quality of soils in these countries, and to assess the potential impact of new management practices on the soil and on the wider environment.

This book is a printed edition of the Special Issue "Enhancing Soil Health to Mitigate Soil Degradation" that was published in Sustainability