Spatial ana lyze and multicriteria evaluation of agricultural quality off-season maize "Safrinha" in middle Paranapema river valley, SP, Brazil / Analise espacial e multicriterial da qualidade das lavouras de milho "Safrinha" no medio Paranapema

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Even though off-season or winter maize ("safrinha") today accounts for a large fraction of Brazilian maize production, and has displayed a significant increase in yield during the past few years, this crop is still associated with low technology and low yield. The first part of this study analyzes the statistics and relations among several variables of agricultural quality (items of quality verification): planting date; crop mulch cover; row spacing; plant stand and population; problem plants; plant spacing; weed infestation; harvest losses. The second part analyzes the spatial correlation of these variables among different plots sampled and maps the distribution by using spatial statistical tools in the Middle Paranapanema River Valley. In the third part, the variables were used as criteria in a multicriteria evaluation (MCE) that created an agricultural quality maps. Thiessen polygons were used to declustering the basic statistics (mean, variance, coefficient of skewness), minimizing problems introduced by non-random spatial sampling. No-tillage cultivation was statistically discriminated from conventional tillage by several variables, but only crop mulch cover separated no-tillage from winter crop mulch cultivation and conventional tillage. Eighty-five percent of plots studied had stands within acceptable limits and displayed good distribution of plants. Sixty percent of the variables showed spatial continuity among the plots, which permitted mapping by use ordinary kriging. Areas not planted in maize were removed from the spatial analysis using a mask of land use produced by a classification of satellite imagery. Multicriteria evaluation (MCE) combined the Analytic Hierarchy Process (AHP) to weight the criteria, and fuzzy sets were used to normalize the criteria, permitting the evaluation and mapping of agricultural quality of off-season ?safrinha? maize in an area of 1,577 km2. Index terms: tillage systems; quality audit; Thiessen polygons; decision making; analytic hierarchy process (AHP)

ASSUNTO(S)

decision support systems conjuntos difusos seeding direct planting soils sistemas de suporte de decisão geoestatistica semeadura plantio direto geostatistics solos - manejo fuzzy sets

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