Stochastic simulation of maize productivity: spatial and temporal uncertainty

There is emerging interest in evaluating the uncertainty of agricultural production to support the production process and for guidance in decision making. The main objective of this work was to estimate the spatial and temporal maize yield uncertainty using stochastic simulation techniques to reduce the economic risk considering the producer risk profile and the international prices of maize and inputs. The results showed that (i) the class yield percentage variation in yield stochastic simulation depends on the sampling density; (ii) higher sampling densities promote an overestimation of low and high yield values compared to those of real yield data; (iii) reducing sampling density promotes the low and high values of overestimation reduction while increasing the central classes values compared to those of real yield data; (iv) the ideal point density for yield stochastic simulation is approximately 65 points/ha; (v) in Mediterranean environments, more than 3–4 years’ worth of real yield data considered as a whole do not seem to improve the parcel level of confidence when cropping irrigated maize; and (vi) the number of equiprobable surfaces that were generated by sequential Gaussian simulation helped to calculate the yield class uncertainty and permitted the study of class yield probabilities for a particular position of the parcel and, therefore, to manage the yield risk and support future decisions. The approach that is presented in this paper may increase prior knowledge of agricultural parcel behavior in the absence of multi-year data, thereby increasing the possibility of reducing economic risks

The fractal dimension of agricultural parcels considering maize yield

Before making any decisions, all farm managers would like to have some indication about the effectiveness of a particular investment, especially when investing in precision agriculture technologies. Usually, the best indicator should be associated with the yield geometric complexity and its spatial and temporal dynamics. The fractal dimension of corn yield in a given year was calculated for six studied parcels, considering the fractal dimension of yield buffer zones above and below average yield. The less complex geometries usually have a fractal dimension close to the unit which can reach a value close to 2 in more complex geometries. This study shows that the number of yield buffer zones, above or below average yield, changes over time, with a different pattern, from parcel to parcel, and that there is a greater change in the smaller yield buffer zones compared to the larger ones. Fractal dimension can be a very strong indicator when the spatial complexity of a particular parcel is considered, and it is therefore a strong indicator of the greater or lesser need for precision agriculture technologies. The higher the fractal dimension of a given parcel, the higher will be the economic and environmental return of that parcel, when using precision agriculture technologies

Sustainable agriculture – Poland and Portugal

Papers from communications presented at the Workshop “Agriculture Sustainability, Poland-Portugal”, held in the University of Évora, Portugal, December, 2013

Solo e diferenciação do vinho à escala da exploração no sul de Portugal

Tendo em vista a avaliação da variabilidade espacial da produção e da qualidade do vinho à escala da parcela, apresentam-se resultados preliminares de um estudo em curso no Alentejo. Observou-se uma correlação positiva entre a condutividade eléctrica aparente (ECa) do solo e a presença de solos com maior espessura de horizontes de textura fina, alguns desde a superfície e com argilas de maior CTC. Estes solos têm uma representação crescente nos talhões (T): 5, 2D, 10 e 12. Em 2012, esta sequência (excluindo T10) também correspondeu ao decréscimo do NDVI e da produção de uva e ao aumento da nota de prova do vinho

Use of geophysical survey as a predictor of the edaphic properties variability in soils used for livestock production

The spatial variability in soils used for livestock production (i.e. Natraquoll and Natraqualf) at farm and paddock scale is usually very high. Understanding this spatial variation within a field is the first step for site-specific crop management. For this reason, we evaluated whether apparent electrical conductivity (ECa), a widely used proximal soil sensing technology, is a potential estimator of the edaphic variability in these types of soils. ECa and elevation data were collected in a paddock of 16 ha. Elevation was negatively associated with ECa. Geo-referenced soil samples were collected and analyzed for soil organic matter (OM) content, pH, the saturation extract electrical conductivity (ECext), available phosphorous (P), and anaerobically incubated Nitrogen (Nan). Relationships between soil properties and ECa were analyzed using regression analysis, principal components analysis (PCA), and stepwise regression. Principal components (PC) and the PC-stepwise were used to determine which soil properties have an important influence on ECa. In this experiment elevation was negatively associated with ECa. The data showed that pH, OM, and ECext exhibited a high correlation with ECa (R2=0.76; 0.70 and 0.65, respectively). Whereas P and Nan showed a lower correlation (R2=0.54 and 0.11 respectively). The model resulting from the PC-stepwise regression analysis explained slightly more than 69% of the total variation of the measured ECa, only retaining PC1. Therefore, ECext, pH and OM were considered key latent variables because they substantially influence the relationship between the PC1 and the ECa (loading factors>0.4). Results showed that ECa is associated with the spatial distribution of some important soil properties. Thus, ECa can be used as a support tool to implement site-specific management in soils for livestock use

Evaluation of vineyard growth under four irrigation regimes using vegetation and soil on-the-go sensors

Precision agriculture is a useful tool to assess plant growth and development in vineyards. The present study focused on spatial and temporal analysis of vegetation growth variability, in four irrigation treatments with four replicates. The research was carried out in a vineyard located in the southwest of Spain during the 2012 and 2013 growing seasons. Two multispectral sensors mounted on an all-terrain vehicle (ATV) were used in the different growing seasons/stages in order to calculate the vineyard normalized difference vegetation index (NDVI). Soil apparent electrical conductivity (ECa) was also measured up to 0.8m soil depth using an on-the-go geophysical sensor. All measured data were analysed by means of principal component analysis (PCA). The spatial and temporal NDVI and ECa variations showed relevant differences between irrigation treatments and climatological conditions

Energy efficiency in agriculture. Showcase and alternatives for wheat production in Portugal.

This chapter presents some results obtained in the KBBE.2011.4-04 project “Energy Efficiency in Agriculture - AGREE” supported by the 7th Framework Program. It gives an overview into energy use and energy efficiency in wheat production in various agro-climatic zones of Europe. Among cereals, wheat is the crop with the largest cultivated area in Europe. In 2008, the percentage share of the area occupied by common and durum wheat in the countries analysed in the AGREE project ranged from 2.4% in Portugal to 18.9% in Germany (Gołaszewski et al., 2012). The different production systems in different climates vary substantially in their energy use and energy saving potential. A showcase of conventional wheat production in Portugal, where in 2012 it was cultivated in 54,761 ha (INE, 2013), is presented and some production alternatives are analysed. The main objective was to analyse the effect in the economic results, energy consumption and environmental impacts of three wheat production systems alternatives: 1. no tillage cropping systems, 2. reduction of phosphorous application and 3. the use of supplemental irrigation

Long-term tobacco exposure and immunosenescence: paradoxical effects on T-cells telomere length and telomerase activity

Immunosenescence are alterations on immune system that occurs throughout an individual life. The main characteristic of this process is replicative senescence, evaluated by telomere shortening. Several factors implicate on telomere shortening, such as smoking. In this study, we evaluated the influence of smoking and Chronic Obstructive Pulmonary Disease (COPD) on cytokines, telomere length and telomerase activity. Blood samples were collected from subjects aged over 60 years old: Healthy (never smokers), Smokers (smoking for over 30 years) and COPDs (ex-smokers for ≥15 years). A young group was included as control. PBMCs were cultured for assessment of telomerase activity using RT-PCR, and cytokines secretion flow cytometry. CD4+ and CD8+ purified lymphocytes were used to assess telomere length using FlowFISH. We observed that COPD patients have accelerated telomere shortening. Paradoxically, smokers without lung damage showed preserved telomere length, suggesting that tobacco smoking may affect regulatory mechanisms, such as telomerase. Telomerase activity showed diminished activity in COPDs, while Smokers showed increased activity compared to COPDs and Healthy groups. Extracellular environment reflected this unbalance, indicated by an anti-inflammatory profile in Smokers, while COPDs showed an inflammatory prone profile. Further studies focusing on telomeric maintenance may unveil mechanisms that are associated with cancer under long-term smoking

Vinhos que pensam - parte ii|iii: utilização da condutividade elétrica aparente do solo na instalação e gestão das culturas: exemplificação na vinha

Vinhos que pensam - parte ii|iii: utilização da condutividade elétrica aparente do solo na instalação e gestão das culturas: exemplificação na vinh