Effects of manure nitrogen on vegetables' yield and nitrogen efficiency in Tanzania

Due to an increasing demand of leaf vegetables, and hence their economic importance in the tropics, it is very common that excessive fertilizer N rates are applied to vegetable gardens and fields to attain high yield. This calls for more information on their nutrient requirements. In this study, we designed experiments to explore the effect of organic N levels on the yield and agronomic N use efficiency (ANE) by chinese cabbage (Brassica rapa) and amaranthus (Amaranthus cruentus). The experimental design was a randomized complete block design consisting of chinese cabbage (CC) and amaranthus (AM) with three replicates. Chicken manure (CHM) and cattle manure (CAM) were the source of N. The treatments were 0, 200, 300 kg N ha(-1) and 0, 170, 250 kg N ha(-1) for CC and AM, respectively. Chicken manure resulted in increased fresh and dry matter yield of CC and AM compared to CAM. All treatments at first harvest induced higher marketable yield of vegetables than controls except with low levels of CAM N. At second harvest, only 300 kg CHM N ha(-1) resulted in significantly (P<0.05) higher marketable yield of CC compared to control, while no significant difference observed in AM by 170 kg CAM N ha(-1). Agronomic N use efficiency was decreasing with increasing N levels. Nitrogen levels can be reduced to 200 and 170 kg N ha(-1) for CC and AM without significantly affecting the yield

Phytoextraction of phosphorus for ecological restoration: application of soil additives

The European Habitats Directive urges the European member states to take measures for maintaining and restoring natural habitats. In Flanders (Belgium) and the Netherlands, the surface area of nature reserves is intended to be enlarged with 38 000 ha and 150 000 ha, respectively, what is mainly to be realised on former agricultural land. In order to restore species rich nature habitats on former agricultural land, it is crucial to decrease the availability of nutrients and a limitation for plant growth by at least one nutrient should be ensured. The former fertilization of P in the agricultural context results in an immense P pool fixated to the soil and this is one of the main problems hindering the ecological restoration. We focus on an alternative restoration method, the phytoextraction of P, also P-mining. This is the deprivation of soil P with a crop with high P-use efficiency and non-P fertilization. This method allows the gradual transition from agricultural land use towards nature management. Up until now there have only been estimations of the P-mining duration time from the initial phase of the mining-process. In order to estimate the P-extraction over time the experiments take place on a soil-P-chronosequence. A controlled pot experiment was set up with soil from three former agricultural sites with different soil-P-levels, Lolium perenne was sown and chemical and biological compounds were added to enhance the bioavailability of P for plant-uptake. The additives used were two concentrations of humic acids, phosphorus solubilising bacteria and arbuscular mycorrhizal fungi. Largest effects of the soil additions on the biomass production were measured in the lowest soil-P-level. Limitation by P in the Mid and Low P soils was very pronounced. The phytoextraction of P will slow down with soil P level decreasing in time. The effect of the soil additions is discussed

Case Study - Belgium, Sustainable Agriculture and Soil Conservation (SoCo Project)

This Technical Note 'Case Study ¿ Belgium' is part of a series of case studies within the ¿Sustainable Agriculture and Soil Conservation¿ (SoCo) project. Ten case studies were carried out in Belgium, Bul-garia, the Czech Republic, Denmark, France, Germany, Greece, Italy, Spain and the United Kingdom between spring and summer 2008. The selection of case study areas was designed to capture differ-ences in soil degradation processes, soil types, climatic conditions, farm structures and farming prac-tices, institutional settings and policy priorities. A harmonised methodological approach was pursued in order to gather insights from a range of contrasting conditions over a geographically diverse area. The case studies were carried out by local experts to reflect the specificities of the selected case studies.JRC.DDG.J.5-Agriculture and Life Sciences in the Econom