Monte Carlo simulation that was controlled with nitrogen utilization rate and yield measurement error as a random value was done to enable discussion on using yield maps that were verified with a system for SSCM (Site-Specific Crop Management).
Smaller yield-measurement error resulted in decreased yield variations. However, if the error was less than 10%, this decrease was not that great. When the yield measurement error was larger than 20%, there was the possibility of decreasing it even more with a corrected Kriging value, taking spatial structural dependence into account. We also confirmed that repeating SSCM for a few years was much more effective in predicting yields than doing it for one year.

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Destructive analysis was used to estimate the half-monthly nitrogen content and related growth parameters of drip-fertigated autumn cucumber.
Three fertilizing treatments were compared. The amount of nitrogen applied half-monthly varied independently, but the total amount was kept the same. There was little difference in the yield or growth of cucumber among the patterns of nitrogen application, which suggests that soil has a buffering effect on cucumber yield even if the amount of nitrogen fertilizer changed.
Destructive analysis found a significant correlation between nitrogen content of cucumber plant and the number of increased leaves: (absorbed nitrogen (g/m2/14 days)=increased leaves (no./m2/14 days)×0.0383+1.856). This relationship suggests that the amount of nitrogen required can be assessed by counting the leaves twice a month.

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Organic broccoli was grown in the fall of 2001 and 2002 at the Experimental Farm, Ibaraki University. The objective was to determine the yield responses, food qualities, and weeds suppression in a no-till production system in which mulch treatments included cover crops of forage soybean and Japanese millet as compared with the conventional cultivation production system. Two different killing cover crop methods that were the use of bush cutter and hammer knife mower, were applied to all mulch treatments.
Millet cover crop biomass showed the highest value that the ranged from 580kg/10a to 636kg/10a. Soybean N contents showed the highest value that the ranged 2.8kgN/10a to 6.3kgN/10a. Yields and head mass increased for millet mulch at an early harvest stage in both years. However, total yields were no significant differences between cover crop mulches and the conventional cultivation system. Broccoli sugar contents for millet mulch showed higher values compare with other treatment, and nitrate contents usually showed the lowest value. On the other hands, broccoli nitrate content for soybean mulch usually showed higher values comparewith other treatment. These results suggest that millet mulch would be an appropriate technique for organic broccoli production system because that would provide adequate soil nutrient condition.

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