Agriculture and fishing are the primary source of almost all our food, as well as of many other products, so remain vital activities even though their share in the economy is small and in continuous decline. Partly for this reason public policy in these areas is almost entirely integrated at European level in the Common Agricultural Policy (CAP) and Common Fisheries Policy (CFP). Forestry policies are also heavily affected by EU-level decision-making. As agriculture dominates in terms of direct contribution to GDP and numbers of people engaged in it, as well as accounting for the largest amount of public support expenditure, it is agriculture that will receive the greatest attention here.

Agriculture, Forestry and Fisheries

http://www.css.cornell.edu/faculty/lehmann/publ/Geoderma%20105,%2021-48,%202002%20Solomon.pdf

Phosphorus forms and dynamics as influenced by land use changes in the sub-humid Ethiopian highlands

Fertility management of tropical acid soils for sustainable crop production.

Phosphorus has been identified as a major factor involved in decreasing water quality through its role in eutrophication, and there is now a focus on controlling nonpoint agricultural P sources. This work was conducted to identify how biosolids applications under current regulations have affected the forms and release potential of P in agricultural soils. We collected samples from eight farms with a history of biosolids amendments, selecting fields that had setback areas (where biosolids applications were not permitted) to allow comparison of amended and unamended soils. We analyzed these soils for P fractions (soluble P, Al-P, Fe-P, reductant soluble P, and Ca-P; their sum equals total P), sequentially desorbable P (Fe-strip), oxalate P, Al and Fe, Mehlich-1 P, and the degree of P saturation. Our results show that following a N-based biosolids nutrient management plan can significantly increase total P (from 403 to 738 mg kg -1 ) and initially desorbable P (from 32 to 61 mg kg -1 ). The main soil components associated with P retention (Al 0x and Fe 0x ) also tended to be increased by biosolids amendment and this may help mitigate P release. Biosolids amendment significantly increased Fe-P (from 137 to 311 mg kg -1 ), probably due to Fe added to biosolids during production, and there was also a strong trend for higher Al-P where biosolids had been applied. Desorbable P was initially greatest from biosolids sites, but with increasing extractions, the release converged towards that from the setback areas. Mehlich-1 P and P ox , were good predictors of desorbable P release, as measured by one and five sequential extractions with Fe-strips. Desorbable P, by both one and five Fe-strip extractions, was more closely correlated with Al-P than Fe-P, especially in setback areas, indicating that Al-P is probably the most important source of desorbable P independent of biosolids amendment. This work indicates the importance of considering P availability at agricultural biosolids application sites and of maintaining setback areas near water bodies, where no biosolids may be applied, to reduce the risk of P losses.

Phosphorus fractionation in biosolids-amended soils: relationship to soluble and desorbable phosphorus.

Integrated soil fertility and plant nutrient management in tropical agro-ecosystems: a review.

The capacity to sorb P varied among some Ethiopian soils. Volcanic ash soils sorbed the maximum P while Fluvisols and Regosols sorbed the least. Sorption of P was significantly correlated with exchangeable and extractable forms of Fe and Al as well as pH and organic matter. But is was not related to the clay content of the soils. The role of Al was more important than that of Fe even though more dithionite and oxalate extractable Fe than Al was found in all soils.

Phosphorus status of some Ethiopian soils. I. Sorption characteristics

The P status of 32 surface soils from various locations of Ethiopia was studied. Total P content of the soils ranged 185−1981 ppm. The relative abundance of the various inorganic P fractions was in the order of calcium-P (Ca-P)>reductant-P (red-P)>iron-P (Fe-P)>aluminum-P (Al-P). Organic P on the average constituted about 41% of the mean total P content of the soils. Multiple correlation analysis of the data showed that the various P fractions were significantly correlated with total P in the soils. Available P in the soils was estimated by eight chemical methods. The lowest mean P value was obtained with the Bray I method and the highest was found with Truog's method (.)

I. Haque

Papers

Phosphorus status of some Ethiopian soils. I. Sorption characteristics

Phosphorus status of some Ethiopian soils. II. Forms and distribution of inorganic phosphates and their relation to available phosphorus