Dynamics of spatial variability of millet growth and yields at three sites in Niger, West Africa and implications for precision agriculture research

This paper focuses on possibilities for using a simple scoring technique to make estimates of millet yield. Estimates are intended to be used for defining application rates of manure in the context of low-tech precision agriculture. Yields from 1995 and 1996 at three locations were related to scoring, soil data and elevation. Kriging was used to interpolate point data to areas. Several procedures for pattern comparison were applied. Because scoring data were available at a much higher density than yield data a sensitivity analysis was made to compare scoring and yield. Correlations between scoring and yield ranged from 0.42 to 0.91. During a separate experiment the optimal time for scoring turned out to be approximately 3 months after seeding for the local varieties of 120 days, but 2 months is convenient for farmers to locally apply chemical fertilizer. R-2 values ranging from 0.15 to 0.60 were observed for soil data and yield, subject to local conditions and changes in weather. We conclude that scoring is a cheap and reliable procedure to identify field patterns which can form the basis for precision agriculture. (C) 2000 Elsevier Science Ltd. All rights reserved.