The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Alex B Mcbratney - One of the best experts on this subject based on the ideXlab platform.
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an integrated framework for software to provide yield data cleaning and estimation of an opportunity index for site specific Crop Management
Precision Agriculture, 2013Co-Authors: Wei Sun, Alex B Mcbratney, B M Whelan, Budiman MinasnyAbstract:This paper proposes an integrated framework for software that provides yield data cleaning and yield opportunity index (Y i ) calculation for site-specific Crop Management (SSCM). The artifacts in many yield data sets, which inevitably occur, can pose a significant effect on the validity of Yi. Automated and standardised yield correction procedures were designed to improve the data quality by removing: (1) unreasonable outliers; (2) distribution outliers (globally and locally); and (3) position errors. The calculation of Yi uses two aspects of Crop yield assessment, the magnitude of yield variation and the spatial structure of the variation. The cleaning algorithms were applied to four yield data sets with known integrity issues to demonstrate effectiveness. Approximately 13–20 % of the original yield data were removed, and this resulted in an increased mean yield of 0.13 t/ha (average). The semivariograms of cleaned data were shown to possess smaller nugget values compared with the original data. The opportunity index calculation algorithm was demonstrated on a field with nine seasons of yield data. The results demonstrated that using a ranking of Yi provides a rational, agronomic assessment of the opportunity for SSCM based on the quantity and pattern of production variability displayed in yield data sets. This provides farm managers with a rapid way to assess whether the observed variability deserves further investigation and eventual investment in SSCM operations.
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field scale experiments for site specific Crop Management part ii a geostatistical analysis
Precision Agriculture, 2004Co-Authors: M J Pringle, Alex B Mcbratney, Simon E CookAbstract:Part II analyses approach C experiments. Field-scale experiments were applied to four wheat fields in the Western Australian wheat belt. Different experimental designs were used two two-dimensional sine-waves, a chequerboard, and a two-factor strip arrangement. In each experiment, the yield associated with a particular treatment was predicted by kriging to where the other treatments were located. Different forms of kriging were investigated. Co-located cokriging, using the previous-season yield map as a covariate, was the most promising. The kriged data were then modelled with polynomial yield response functions. The outcome was a map for each field that described the optimum application of experimental input. The requirements varied continuously across the field, and could justify future site-specific Crop Management. The two-factor strip experiment was the most successful of those presented; the field on which it was used showed relatively strong responses to the applied inputs. The other sites were affected by lack of rain and/or design flaws. The underlying philosophy is sound, but the method proposed is time-consuming and inefficient. We hope that this paper can stimulate further research on the subject.
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a preliminary approach to assessing the opportunity for site specific Crop Management in a field using yield monitor data
Agricultural Systems, 2003Co-Authors: M J Pringle, Alex B Mcbratney, B M Whelan, J A TaylorAbstract:Abstract This paper proposes an Opportunity Index (Oi) for site-specific Crop Management (SSCM). In contrast to the traditional practice of uniform agronomic Management, SSCM aims to match controllable inputs with spatially variable Crop requirements. Farmers, however, are often left wondering how their yield maps can be used to justify a change to SSCM. The Oi is a single number that may be used in the process of this justification. The Oi is based on three components: (1) the magnitude of variation present in a yield map, relative to a certain threshold; (2) the average area within which yield is autocorrelated, relative to the minimum area within which variable-rate controllers (which physically implement SSCM) can reliably operate; and, (3) the economic and environmental benefit of SSCM relative to uniform Management. The Oi was calculated for 20 Australian Cropping fields and compared with b′ [Journal of Agricultural Sciences, Cambridge, 28 (1938)], which is an alternative method of quantifying the Management opportunity from yield variation. A weak negative correlation was found to exist. Results suggest that a good opportunity for site-specific Crop Management exists when the Oi is greater than 20, although this is only a tentative recommendation.
Philippe Debaeke - One of the best experts on this subject based on the ideXlab platform.
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adaptation of Crop Management to water limited environments
European Journal of Agronomy, 2004Co-Authors: Philippe Debaeke, Abdellah AboudrareAbstract:Farmers must combine various Crop Management strategies to cope with water deficit resulting from soil, weather or limited irrigation: drought escape, avoidance or tolerance, Crop rationing, irrigation (supplemental, deficit). These strategies can be translated into six objectives: (i) increasing soil stored water at plant sowing, (ii) increasing soil water extraction, (iii) reducing the contribution of soil evaporation to total water-use, (iv) optimizing the seasonal water use pattern between pre- and post-anthesis, (v) tolerate water stress and recover after stress alleviation, and (vi) irrigate at the most-sensitive growth phases. To reach these objectives, tactical decisions concern soil tillage, type of Crop and cultivar, sowing date and density, N fertilization, irrigation timing, amount and frequency. Flexible Crop Management systems based on decision rules should be preferred to the recommendation of fixed packages of techniques. Timing, intensity, and predictability of drought (intermittent, terminal) are important features for choosing the Cropping alternatives. Simulation models may help the farmer to select best-bet Management options on the basis of historical long-term weather records. Simple soil and plant indicators associated with real-time decision support systems should be developed to revise the initial Management plan by integrating in-season weather information.
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influence of Crop Management on sunflower stem canker diaporthe helianthi
Agronomie, 2003Co-Authors: Philippe Debaeke, Andre Estragnat, Raymond ReauAbstract:Le phomopsis du tournesol, maladie cryptogamique causee par Diaporthe helianthi Munt.-Cvet. et al., est responsable de pertes de rendement pouvant atteindre 40 %. Au travers d'une collaboration INRA-Cetiom (1994-2000), les effets de la conduite de culture du tournesol sur la frequence et la gravite des attaques de phomopsis ont ete etudies experimentalement dans la region toulousaine. Il a ete montre que la densite de peuplement augmente la proportion de tiges presentant des taches de phomopsis. Par contre, l'augmentation des doses d'azote peut se traduire dans certaines conditions par une diminution de la frequence de tiges attaquees. Le retard de semis reduit le risque de contamination foliaire et de degât sur tige. Des conduites integrant ces techniques ont ete evaluees pendant 7 annees : si la strategie de rationnement vegetatif (reduction de la densite de peuplement et de la fertilisation azotee) n'est pas suffisante a elle seule pour maitriser le phomopsis, son association avec le semis tardif permet d'atteindre des niveaux d'attaque proches de ceux obtenus en semis precoce, proteges chimiquement. La rentabilite des conduites « bas intrants », ne recevant pas de fongicides, n'est assuree que si l'on utilise des varietes peu a tres peu sensibles et en l'absence de forte hygrometrie en juin.
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a simple model to interpret the effects of sunflower Crop Management on the occurrence and severity of a major fungal disease phomopsis stem canker
Field Crops Research, 2003Co-Authors: Philippe Debaeke, Andre EstragnatAbstract:Abstract Phomopsis stem canker ( Diaporthe helianthi Munt.-Cvet. et al.) causes drastic reductions in yield and oil content in the sunflower ( Helianthus annuus L.) Crop. The use of disease-tolerant genotypes and fungicides is the basis of current disease control. Both for economic and environmental reasons, control by means of cultural practices should be promoted more. From 1992 to 2002, INRA and Cetiom collaborated to study the effects of sunflower Crop Management on the frequency and severity of Phomopsis attacks. As plant density and nitrogen rate significantly affect the development of sunflower leaf area, use of the fraction of photosynthetically active radiation intercepted by the canopy (fPARi) was suggested as a synthetic indicator of canopy Management. In 1994, an exponential relation was observed between the proportion of sunflower stems bearing a Phomopsis lesion in mid-August and the fPARi by the canopy at anthesis in early July. This relation was successfully tested for a range of unprotected situations (1994–2000) corresponding to moderate infection pressure and various combinations of plant density and N fertilization. Such a reference curve was used to analyse the response of sunflower to stem canker infection in a range of cultural conditions: (1) high inoculum; (2) drought during head development or soon after leaf infection; (3) application of a fungicide at the early stages of flower bud development; (4) late sowing (May); (5) use of very susceptible or resistant genotypes. This simple model could help to interpret the origin of genotypic susceptibility to stem canker (Crop architecture and/or physiology) and also to predict the potential risk of disease development for a given Management scenario.
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influence of sunflower helianthus annuus l Crop Management on phoma black stem phoma macdonaldii boerema
Crop Protection, 2003Co-Authors: Philippe Debaeke, Andre PeresAbstract:Abstract Collaborative work was done by INRA and Cetiom from 1994 to 2001 to characterize and evaluate the effects of individual cultural techniques and Crop Management systems applied on sunflower (Helianthus annuus L.) on the frequency and severity of fungal attacks by Phoma macdonaldii Boerema at stem and collar levels. The proportion of stems infected by Phoma black stem always increased with additional nitrogen and water supply. In conditions of excessive nitrogen nutrition, the most severe attacks were observed for the lowest plant densities. In conditions of limiting water and nitrogen, the heaviest attacks were observed for the highest densities. With limited water, the water holding capacity of the petiole groove might be responsible for the success of infection whereas when nitrogen was limiting, the more favourable microclimate of dense stands could explain the higher level of infection. When these cultural factors (irrigation, nitrogen and plant density) were expressed via their effects on the plant canopy using leaf area index or fraction of photosynthetically active radiation intercepted (fPARi) at anthesis, it was possible to rank the proportion of infected stems and the number of lesions per stem according to the increasing level of Crop intensification.
Abdellah Aboudrare - One of the best experts on this subject based on the ideXlab platform.
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adaptation of Crop Management to water limited environments
European Journal of Agronomy, 2004Co-Authors: Philippe Debaeke, Abdellah AboudrareAbstract:Farmers must combine various Crop Management strategies to cope with water deficit resulting from soil, weather or limited irrigation: drought escape, avoidance or tolerance, Crop rationing, irrigation (supplemental, deficit). These strategies can be translated into six objectives: (i) increasing soil stored water at plant sowing, (ii) increasing soil water extraction, (iii) reducing the contribution of soil evaporation to total water-use, (iv) optimizing the seasonal water use pattern between pre- and post-anthesis, (v) tolerate water stress and recover after stress alleviation, and (vi) irrigate at the most-sensitive growth phases. To reach these objectives, tactical decisions concern soil tillage, type of Crop and cultivar, sowing date and density, N fertilization, irrigation timing, amount and frequency. Flexible Crop Management systems based on decision rules should be preferred to the recommendation of fixed packages of techniques. Timing, intensity, and predictability of drought (intermittent, terminal) are important features for choosing the Cropping alternatives. Simulation models may help the farmer to select best-bet Management options on the basis of historical long-term weather records. Simple soil and plant indicators associated with real-time decision support systems should be developed to revise the initial Management plan by integrating in-season weather information.
M J Pringle - One of the best experts on this subject based on the ideXlab platform.
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field scale experiments for site specific Crop Management part ii a geostatistical analysis
Precision Agriculture, 2004Co-Authors: M J Pringle, Alex B Mcbratney, Simon E CookAbstract:Part II analyses approach C experiments. Field-scale experiments were applied to four wheat fields in the Western Australian wheat belt. Different experimental designs were used two two-dimensional sine-waves, a chequerboard, and a two-factor strip arrangement. In each experiment, the yield associated with a particular treatment was predicted by kriging to where the other treatments were located. Different forms of kriging were investigated. Co-located cokriging, using the previous-season yield map as a covariate, was the most promising. The kriged data were then modelled with polynomial yield response functions. The outcome was a map for each field that described the optimum application of experimental input. The requirements varied continuously across the field, and could justify future site-specific Crop Management. The two-factor strip experiment was the most successful of those presented; the field on which it was used showed relatively strong responses to the applied inputs. The other sites were affected by lack of rain and/or design flaws. The underlying philosophy is sound, but the method proposed is time-consuming and inefficient. We hope that this paper can stimulate further research on the subject.
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a preliminary approach to assessing the opportunity for site specific Crop Management in a field using yield monitor data
Agricultural Systems, 2003Co-Authors: M J Pringle, Alex B Mcbratney, B M Whelan, J A TaylorAbstract:Abstract This paper proposes an Opportunity Index (Oi) for site-specific Crop Management (SSCM). In contrast to the traditional practice of uniform agronomic Management, SSCM aims to match controllable inputs with spatially variable Crop requirements. Farmers, however, are often left wondering how their yield maps can be used to justify a change to SSCM. The Oi is a single number that may be used in the process of this justification. The Oi is based on three components: (1) the magnitude of variation present in a yield map, relative to a certain threshold; (2) the average area within which yield is autocorrelated, relative to the minimum area within which variable-rate controllers (which physically implement SSCM) can reliably operate; and, (3) the economic and environmental benefit of SSCM relative to uniform Management. The Oi was calculated for 20 Australian Cropping fields and compared with b′ [Journal of Agricultural Sciences, Cambridge, 28 (1938)], which is an alternative method of quantifying the Management opportunity from yield variation. A weak negative correlation was found to exist. Results suggest that a good opportunity for site-specific Crop Management exists when the Oi is greater than 20, although this is only a tentative recommendation.
T R Mayr - One of the best experts on this subject based on the ideXlab platform.
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mapping potential Crop Management zones within fields use of yield map series and patterns of soil physical properties identified by electromagnetic induction sensing
Precision Agriculture, 2005Co-Authors: J A King, P M R Dampney, R M Lark, H C Wheeler, R I Bradley, T R MayrAbstract:Investment in precision farming technologies can be expensive and is not expected to be cost-effective for every farm. Previous research and farm experience has shown that the amount of soil variability across a farm and within a field is of key importance for determining potential benefits from the adoption of precision farming. The research reported here evaluates the analysis of yield map sequences and electromagnetic induction (EMI) soil sensing as potentially cost-effective methods for identifying and mapping soil-determined “Management zones” within fields. Both methods are shown to provide useful information for the provisional delineation of soil type boundaries and Crop Management zones, though soil examination in the field is still necessary to confirm specific soil characteristics.