Variability in wheat crop production based on management zones in humid pampas region, Argentina

LOPEZ DE SABANDO, M.J.; DIAZ ZORITA, MARTIN; MERCURI, P.

Denver, Colorado

Conferencia; 10 th International Conference on Precision Agriculture; 2010

Colorado State University, International Plant Nutrition Institute, and Foundation for Agronomic Research

Crop productivity within fields is heterogeneous and it responds to the variation in crop patterns associated to crop management, previous crop management practices, as well as random and natural crop management factors. The methodologies for delimitation of management zones (MZ) within production fields differ based on their application objectives. The objectives of the present study were (i) to quantify the coincidence of defined areas based on 8 methodologies for zone delimitation, (ii) to quantify differences in yields and nitrogen use in wheat crops (Triticum aestivum L.) among MZ in relation to the 8 selected methodologies, and (iii) using one methodology selected in (ii) to quantify differences in wheat productivity in MZ in relation to N-fertilization levels (0 and 160 kg N ha-1). In 3 wheat production fields in the Humid Pampas region (Argentina) high (H), medium (M) and low (L) productivity MZ were defined based on previous crop yield mapping (YM), elevation, normalized vegetation index (NDVI) of crops, NDVI of Gramineae, previous crop management practices, soil mapping (SM), photo-interpretation of satellite images (PhSI), and standardized sums of YM and SM. Out of 23 analyzed combinations of zone delimitation methodologies, 5 displayed coincidences higher than 60 %. Wheat production was determined in each MZ based on 5 N fertilization levels. When MZ productivity increased, maximum yields were obtained with lower levels of N available (soil + fertilizer). Considering productivity and nitrogen use, higher differences among productivity MZ were found based on PhSI, productivity MZ H was higher than productivity MZ L in minimum and maximum yields (44 % and 7 %), and in N use efficiency (59 %). Productivity MZ H yield was a 26 and 15 % higher than productivity MZ L based on N fertilization, which was 0 and 160 kg of N ha-1. In lower nitrogen levels, differences between MZ increased. Forty percent of the difference in wheat production between MZ H and MZ L decreased with the application of 160 kg N ha-1.