Evaluation of water use, yield and water productivity of a high-density orchard (cv. Cobrançosa) subjected to different irrigation regimes – An account of four years

The impact of different irrigation scheduling regimes on the water use, yield and water productivity from a high-density olive grove cv. Cobrançosa in southern Portugal was assessed during the irrigation seasons of 2011, 2012, 2013 and 2014. The experiments were conducted in a commercial olive orchard at the Herdade Álamo de Cima, near Évora (38o 29' 49.44'' N, 7o 45' 8.83'' W; alt. 75 m) in southern Alentejo, Portugal. The orchard was established with 10-year old Cobrançosa trees in grids of 8.0 x 4.2 m (300 trees ha-1) in the E-W direction, and experiments conducted on a shallow sandy loam Regosoil Haplic soil. From mid-May to the end of September the orchard was irrigated and three plots were subjected to one of two irrigation treatments: a control treatment A, irrigated to replace 100% ETc, a moderate deficit irrigation treatment B irrigated to 70% of ETc, and a more severe deficit irrigation treatment C that provided for approximately 50% of ETc. Daily tree transpiration rates were obtained by continuously monitoring of sap flow in representative trees per treatment. Among the irrigated treatments, water use efficiency (WUE, ratio of water used to irrigation- water applied) of treatment C was the highest, with a value of 0.89, being treatment B slightly lower, with a WUE of 0.76. Olive harvest for 2012 was an exceptional “on year”. Bearing yields showed contrasting differences within years where an “on year” was followed by an “off year”. In 2011 and 2012 treatment B yields were 41 and 50% higher than treatment C, respectively. In 2013 treatment B yield was 45% higher than yield of the fully irrigated treatment A, and treatment C showed practically the same yield than treatment A. In the “on year” of 2014 treatment B averaged 48% higher yield than treatment C. Treatment B farm irrigation water productivity (WPI-Farm, ratio of yield to water applied) was the highest among all treatments. Treatment A showed the lowest conversion efficiency of all treatments, indicating treatment B as the adequate deficit irrigation treatment for our Cobrançosa orchard

Effect of trees in the soil nutrient concentration and pasture produtivity in Mediterranean silvo-pastoral systems

Silvo-pastoral are mixed systems of trees and grass, which have been proposed as a means to extend the benefits of forest to farmed land. Agro-forestry systems under semi-arid Mediterranean conditions, called montados in Portugal and dehesas in Spain, cover substantial areas in the world. These silvo-pastoral systems are the most extensive European agro-forestry system, as they cover 3.5–4.0 Mha in Spain and Portugal. Long-term studies are essential to assess the magnitude of the temporal nutrient flow dynamics in terrestrial ecosystems and to understand the response of these systems to fertilizer management. In order to implement the conservation task and recovery of resources through silvo-pastoral systems it is necessary to know and correct potential limiting factors, especially the soil factor, and this requires agronomic knowledge as well as the implmentation of the available new technologies. In this context, this task aims at a better understanding of the contribution of the two components of montado ecosystem (trees and herbaceous vegetation) on the soil nutrient and water dynamics, that allow for the interpretation of the variability of pasture dry matter yield and help the farmer in the management of tree density. Collaterally the task will evaluate and calibrate new technologies that simplify the monitoring of soil, grassland, trees and grazing animals.

Soil quality assessment in conservation agriculture systems

Soil is a key resource that provides the basis of food production and sustains and delivers several ecosystems services including regulating and supporting services such as water and climate regulation, soil formation and the cycling of nutrients carbon and water. During the last decades, population growth, dietary changes and the subsequent pressure on food production, have caused severe damages on soil quality as a consequence of intensive, high input-based agriculture. While agriculture is supposed to maintain and steward its most important resource base, it compromises soil quality and fertility through its impact on erosion, soil organic matter and biodiversity decline, compaction, etc., and thus the necessary yield increases for the next decades. New or improved cropping systems and agricultural practices are needed to ensure a sustainable use of this resource and to fully take the advantages of its associated ecosystem services. Also, new and better soil quality indicators are crucial for fast and in-field soil diagnosis to help farmers decide on the best management practices to adopt under specific pedo-climatic conditions. Conservation Agriculture and its fundamental principles: minimum (or no) soil disturbance, permanent organic soil cover and crop rotation /intercropping certainly figure among the possibilities capable to guarantee sustainable soil management. The iSQAPER project – Interactive Soil Quality Assessment in Europe and China for Agricultural Productivity and Environmental Resilience – is tackling this problem with the development of a Soil Quality application (SQAPP) that links soil and agricultural management practices to soil quality indicators and will provide an easy-to-use tool for farmers and land managers to judge their soil status. The University of Évora is the leader of WP6 - Evaluating and demonstrating measures to improve Soil Quality. In this work package, several promising soil and agricultural management practices will be tested at selected sites and evaluated using the set of soil quality indicators defined for the SQAPP tool. The project as a whole and WP6 in specific can contribute to proof and demonstrate under different pedoclimatic conditions the impact of Conservation Agriculture practices on soil quality and function as was named the call under which this project was submitted.

Sugarcane Water Productivity Assessments in the São Paulo state, Brazil.

São Paulo state, Brazil, has been highlighted by the sugarcane crop expansion. The actual scenario of climate and land use changes, bring attention for the large-scale water productivity (WP) analyses. MODIS images were used together with gridded weather data for these analyses. A generalized sugarcane growing cycle inside a crop land mask, from September 2011 to October 2012, was considered in the main growing regions of the state. Actual evapotranspiration (ET) is quantified by the SAFER (Simple Algorithm for Evapotranspiration Retrieving) algorithm, the biomass production (BIO) by the RUE (Radiation Use Efficiency) Monteith?s model and WP is considered as the ratio of BIO to ET. During the four generalized sugarcane crop phases, the mean ET values ranged from 0.6 to 4.0 mm day-1; BIO rates were between 20 and 200 kg ha-1 day-1, resulting in WP ranging from 2.8 to 6.0 kg m-3. Soil moisture indicators are applied, indicating benefits from supplementary irrigation during the grand growth phase, wherever there is water availability for this practice. The quantification of the large-scale water variables may subsidize the rational water resources management under the sugarcane expansion and water scarcity scenarios.

Carbon in humic fractions of organic matter in soil treated with organic composts under mango cultivation.

Soil organic matter (SOM) plays a key role in maintaining the productivity of tropical soils, providing energy and substrate for the biological activity and modifying the physical and chemical characteristics that ensure the maintenance of soil quality and the sustainability of ecosystems. This study assessed the medium-term effect (six years) of the application of five organic composts, produced by combining different agro-industrial residues, on accumulation and chemical characteristics of soil organic matter. Treatments were applied in a long-term experiment of organic management of mango (OMM) initiated in 2005 with a randomized block design with four replications. Two external areas, one with conventional mango cultivation (CMM) and the other a fragment of regenerating Caatinga vegetation (RCF), were used as reference areas. Soil samples were collected in the three management systems from the 0.00-0.05, 0.05-0.10, and 0.10-0.20 m layers, and the total organic carbon content and chemical fractions of organic matter were evaluated by determining the C contents of humin and humic and fulvic acids. Organic compost application significantly increased the contents of total C and C in humic substances in the experimental plots, mainly in the surface layer. However, compost 3 (50 % coconut bagasse, 40 % goat manure, 10 % castor bean residues) significantly increased the level of the non-humic fraction, probably due to the higher contents of recalcitrant material in the initial composition. The highest increases from application of the composts were in the humin, followed by the fulvic fraction. Compost application increased the proportion of higher molecular weight components, indicating higher stability of the organic matter.

Soil management systems for sustainable melon cropping in the Submedian of the São Francisco Valley.

Changes in soils management systems, including the application of green manure, are able to increase crop productivity. The aim of this study was to propose a soil management system with the use of green manure to improve the nutritional status and melon productivity in the submedian of the São Francisco Valley. The experiment was installed in Typic Plinthustalf and conducted in split plot. There were two soil tillage systems, tillage (T) and no tillage (NT), and three types of green manure (two vegetal cocktails: VC1- 75% legumes (L) + 25% non-legumes (NL); VC2- 25% L+ 75% NL and spontaneous vegetation (SV)). The experimental design was a randomised block with four replications. Fourteen species of legumes, grasses and oilseeds were used for the composition of the plant cocktails. We evaluated production of the dry shoot and root biomass and carbon and nutrient accumulation by green manures and melon plant. Data were subjected to analysis of variance and the treatment means were compared by Tukey´s test (P<0.05). Shoot biomass production and carbon and nutrient accumulation were higher in plant mixtures compared to spontaneous vegetation. The root system of the plant cocktails added larger quantities of biomass and nutrients to the soil to a depth of 0.60 m when compared to the spontaneous vegetation. The cultivation of plant cocktails with soil tillage, regardless of their composition, is a viable alternative for adding biomass and nutrients to the soil in melon crops in semi-arid conditions, providing productivity increases.

Strategies to enhance the productivity of rainfed off-season maize.

In Brazil, off-season rainfed maize is usually affected by limited water due to irregularities in rainfall. Alternatives to mitigate these effects include ground cover to reduce evaporation losses and the use of cultivars with a deeper rooting system. We conducted a study in Goias, Brazil, to evaluate the influence of different crop management strategies to mitigate the effect of limited water in maize yield. Modeling was used to simulate scenarios that consisted of 0, 3.5 and 5.0 t ha-1 of soybean residue left on the soil surface combined with cultivar ideotypes with 0.30 m, 0.50 m 0.70 m deep rooting system grown with 60 and 340 kg ha-1of nitrogen. The results showed that maintaining residue in the soil surface in combination with the use of cultivars with deeper rooting systems favored higher yields of off-season maize. Our results also indicated that a cultivar with rooting system in the top 0.50 m of the soil fertilized with a high nitrogen rate tended to be more efficient in the use of the soil available water

Raman spectroscopy of some complex arsenate minerals—implications for soil remediation

The application of spectroscopy to the study of contaminants in soils is important. Among the many contaminants is arsenic, which is highly labile and may leach to non-contaminated areas. Minerals of arsenate may form depending upon the availability of specific cations for example calcium and iron. Such minerals include carminite, pharmacosiderite and talmessite. Each of these arsenate minerals can be identified by its characteristic Raman spectrum enabling identification.