Application of phosphorus (P) fertilisers to sugarcane fields in Mauritius increased almost four-fold per unit area over the past 60 years. Some of the applied P accumulated in the soils and can therefore be transport...Application of phosphorus (P) fertilisers to sugarcane fields in Mauritius increased almost four-fold per unit area over the past 60 years. Some of the applied P accumulated in the soils and can therefore be transported eventually to surface waters resulting in the eutrophication thereof. Precaution measures such as an appropriate P index as a management tool is required. Source factors (dissolved P, particulate P, P application rates, methods and timing), transport factors (soil erosion, runoff potential and precipitation factor) and a best management practices multiplier were integrated to derive an index for assessing risks of P mobilisation from the island’s sugarcane fields. Farmers and their advisors can use the proposed P index during the planning process before sugarcane fields are planted and will be applicable for the whole crop cycle of 6 - 7 years if factors in the index do not change. The index can be also valuable in the selection of alternative management practices that could reduce the risks of P losses from sugarcane fields where the potential of P movement is initially high. Sensitivity analyses and edge-to-plot field tests showed that the P index needs further improvement, especially the estimation of soil erosion rates. The P index can, however, be applied by farmers and their advisors if they are well informed about the index’s capability.展开更多
This review addresses research done over the past 40 years on different aspects of agricultural phosphorus (P) management for environmental protection. Inputs of P are essential for profitable crop production. Long-te...This review addresses research done over the past 40 years on different aspects of agricultural phosphorus (P) management for environmental protection. Inputs of P are essential for profitable crop production. Long-term application of P to agricultural soils has resulted in elevated levels of soil P. This accumulation may be desirable from an agronomic point of view but it represents a threat to freshwater quality. Indeed, P in runoff from agricultural land is an important component of non-point source pollution and can accelerate eutrophication of lakes and streams. Even very small amounts of P can raise the concentration above the critical value for eutrophication. Excessive eutrophication restricts water use for recreation, industry, and drinking due to the increased growth of undesirable algae and aquatic weeds. Current concerns facing the environmentally sound management of P in agriculture are similar worldwide and revolve around agricultural, economic, and environmental compromises associated with balancing productivity with environmental values. Agricultural P management strategies should be geared towards ensuring that P, a finite earth resource, is not wasted and those soils do not become so enriched with P that there is an unnecessary risk of too much P being mobilized to water from agricultural fields. Approaches, such as soil P testing and either P models or indices have been studied and implemented to mitigate agricultural P losses. Apparently, P indices are preferred instead of P models for this purpose because they are more flexible. A holistic management strategy is therefore suggested by using soil P testing in conjunction with either a P index or a P model.展开更多
文摘Application of phosphorus (P) fertilisers to sugarcane fields in Mauritius increased almost four-fold per unit area over the past 60 years. Some of the applied P accumulated in the soils and can therefore be transported eventually to surface waters resulting in the eutrophication thereof. Precaution measures such as an appropriate P index as a management tool is required. Source factors (dissolved P, particulate P, P application rates, methods and timing), transport factors (soil erosion, runoff potential and precipitation factor) and a best management practices multiplier were integrated to derive an index for assessing risks of P mobilisation from the island’s sugarcane fields. Farmers and their advisors can use the proposed P index during the planning process before sugarcane fields are planted and will be applicable for the whole crop cycle of 6 - 7 years if factors in the index do not change. The index can be also valuable in the selection of alternative management practices that could reduce the risks of P losses from sugarcane fields where the potential of P movement is initially high. Sensitivity analyses and edge-to-plot field tests showed that the P index needs further improvement, especially the estimation of soil erosion rates. The P index can, however, be applied by farmers and their advisors if they are well informed about the index’s capability.
文摘This review addresses research done over the past 40 years on different aspects of agricultural phosphorus (P) management for environmental protection. Inputs of P are essential for profitable crop production. Long-term application of P to agricultural soils has resulted in elevated levels of soil P. This accumulation may be desirable from an agronomic point of view but it represents a threat to freshwater quality. Indeed, P in runoff from agricultural land is an important component of non-point source pollution and can accelerate eutrophication of lakes and streams. Even very small amounts of P can raise the concentration above the critical value for eutrophication. Excessive eutrophication restricts water use for recreation, industry, and drinking due to the increased growth of undesirable algae and aquatic weeds. Current concerns facing the environmentally sound management of P in agriculture are similar worldwide and revolve around agricultural, economic, and environmental compromises associated with balancing productivity with environmental values. Agricultural P management strategies should be geared towards ensuring that P, a finite earth resource, is not wasted and those soils do not become so enriched with P that there is an unnecessary risk of too much P being mobilized to water from agricultural fields. Approaches, such as soil P testing and either P models or indices have been studied and implemented to mitigate agricultural P losses. Apparently, P indices are preferred instead of P models for this purpose because they are more flexible. A holistic management strategy is therefore suggested by using soil P testing in conjunction with either a P index or a P model.
