Suchergebnisse

Greenhouse agriculture typically generates large amounts of waste with plant residue (agricultural biomass) being the most abundant. This residue is generated on a seasonal basis, which complicates the external management of the material. Recently, the European Union (EU) has been implementing a policy based on sustainability through the circular economy that seeks to minimize waste generation. The effect of reusing 3.5 kg·m(−2) tomato plants from the previous season as the only fertilizer versus no fertilization and inorganic fertilization in 215-day tomato cycles after transplanting was studied in this trial. The study was carried out during three seasons in greenhouse agriculture in Almeria (Spain) with the repeated use of the solarization technique. The plant debris had similar production results during two of the three seasons and fruit quality parameters were similar to inorganic fertilization. In addition, some physicochemical variables improved and the biological depressive effect of solarization was mitigated. The results suggest that the reuse of the tomato plant debris as the only fertilizer could be an alternative to conventional fertilization under the conditions tested.

The objective of this study was to evaluate the effect of increasing rates of poultry litter biochar incubated in soil for different periods on soil fertility attributes and the development of the radish plant. An experiment was carried out in a greenhouse at the Federal University of Campina Grande - UFCG. Treatments consisted of the combination of two factors: four incubation times (0, 30, 60, and 90 days) and four biochar rates (12.5, 25.0, 37.5, 50.0 t ha-1), in three replications, totalizing 48 experimental plots, in a completely randomized design. After the incubation period, soil samples were collected from each experimental unit and chemically characterized. Following this, radish was sown and cultivated for up to 30 days. The agronomic development of radish was evaluated based on the following variables: leaf area; leaf area ratio; specific leaf area; shoot biomass production index; transverse and longitudinal tuber diameters; and fresh and dry tuber biomasses. Under the present experimental conditions, biochar increases soil fertility levels and is able to supply nutrients to the plants in a short period, increasing plant variables.

In the oil palm agroforestry system on the Adja Plateau (West Africa), land titling plays an important role. Landowners argue that oil palm fallow (dekan) restores soil fertility, but in the long-term it is also an instrument in the struggle for control over land. A land-titling programme in the study area allowed an analysis of the relationship between titling and soil fertility management that showed two different institutional effects with socio-technical consequences. Titling increased land security for landowners and, although this security initially reduced access to land for tenants, a subsequent introduction of witnessed paper-based contracts enhanced tenants' access to land and improved their security of tenure. Improved titling and more secure tenure reduced conflicts over land and opened possibilities for agricultural intensification. This change was associated with a shift from long-term oil palm fallow to shorter-term land-management practices where tenants and landowners increasingly invested in land through rotations between maize and cowpea (rather than maize mono-cropping) and the use of mineral fertilizers, without increased use of household waste (organic amendment). The paper suggests that sustainable agricultural intensification in agroforestry systems requires institutional changes, based on a mixture of customary and formal rules, in both landownership and rental agreements to access land.

It has been highlighted that forest productivity is related both to species richness and to soil fertility; however, thus far it has not been investigated which of these agents is more important for the productivity. The goal of this study was to examine this problem with regard to Scots pine (Pinus sylvestris L.) stands in Central Europe. The study was conducted in 129 plots located in SW Poland. The productivity of even-aged pine stands was estimated based on site index. Plant species richness was investigated regarding the total richness as well as the richness referring to particular forest strata (overstorey, understorey, herb layer). Soil fertility was studied regarding the nutrients' stocks, the contents of fine-textural classes, pH, the TOC content and the values of Soil Trophic Index. The importance of the variables for the site index was examined using Spearman correlations and the stepwise regression. Productivity of the studied stands was predominantly correlated stronger to species richness than to soil properties being related to its fertility. The higher importance for the productivity of soil variables than of species richness was exclusively found for the poorest plots being represented by Podzols. This study highlights the high importance of species richness occurring in particular forest strata for the forest stand productivity, which could involve consequences for forest economy as well as for CO2 sequestration. Thus, the research delivers strong argument for the conversion of pine mono-stands occurring in Central Europe for mixed forests.

The reuse of treated wastewater, in particular for irrigation, is an increasingly common practice, encouraged by governments and official entities worldwide. Irrigation with wastewater may have implications at two different levels: alter the physicochemical and microbiological properties of the soil and/or introduce and contribute to the accumulation of chemical and biological contaminants in soil. The first may affect soil productivity and fertility; the second may pose serious risks to the human and environmental health. The sustainable wastewater reuse in agriculture should prevent both types of effects, requiring a holistic and integrated risk assessment. In this article we critically review possible effects of irrigation with treated wastewater, with special emphasis on soil microbiota. The maintenance of a rich and diversified autochthonous soil microbiota and the use of treated wastewater with minimal levels of potential soil contaminants are proposed as sine qua non conditions to achieve a sustainable wastewater reuse for irrigation. ; info:eu-repo/semantics/acceptedVersion

Soil fertility depletion presents a negative feedback mechanism that could have impacted early adopters of agriculture. In this paper, we present a formal mathematical analysis of the question whether such feedback can lead to population cycles in the context of early agriculturalists, such as the boom and bust patterns suggested by an increasing amount of evidence for Neolithic Europe. We do this by considering candidates of second-order analytic models that capture dynamical interaction among farmers and soil fertility. Using general mathematical arguments, we show that under plausible conditions, the feedback between population growth and soil resource depletion is unlikely to lead to population cycles. This result is the consequence of two factors. First, there is an important mathematical difference between biotic (i.e. logistic) and abiotic resource replenishment; soil nutrients are better modelled by the abiotic case which leads to more stable dynamics. Second, under realistic conditions, the resource replenishment process has fast time-scales compared to attainable population growth rates, reinforcing the tendency of stable dynamics. Both of these factors play a role when considering early agricultural societies, and imply that nutrient depletion is not a credible mechanism for patterns of boom and bust cycles observed in the archaeological record.