The One-Straw Revolution_ An Introduction to Natural Farming - Masanobu Fukuoka [31]
At first, the red clay soil in my fields was weak and unsuited for growing rice. Brown spot disease frequently occurred. But as the field gradually grew in fertility, the incidence of brown spot disease decreased. Lately there have been no outbreaks at all.
With insect damage the situation is the same. The most important thing is not to kill the natural predators. Keeping the field continuously under water or irrigating with stagnant or polluted water will also lead to insect problems. The most troublesome insect pests, summer and fall leaf-hoppers, can be kept under control by keeping water out of the field.
Green rice leaf-hoppers, living in the weeds over the winter, may become a virus host. If this happens the result is often a loss of ten to twenty percent from rice blast disease. If chemicals are not sprayed, however, there will be many spiders present in the field and one can generally leave the work to them. Spiders are sensitive to even the slightest human tampering and care must always be taken on this account.
Most people think that if chemical fertilizer and insecticides were abandoned agricultural yields would fall to a fraction of the present level. Experts on insect damage estimate that losses in the first year after giving up insecticides would be about five percent. Loss of another five percent in abandoning chemical fertilizer would probably not be far mistaken.
That is, if the use of water in the rice field were curtailed, and the chemical fertilizer and pesticide spraying encouraged by the Agricultural Co-op were abandoned, the average losses in the first year would probably reach about ten percent. The recuperative power of nature is great beyond imagining and after this initial loss, I believe harvests would increase and eventually surpass their original level.
While I was with the Kochi Testing Station, I carried out experiments in the prevention of stem borers. These insects enter and feed on the stem of the rice plant, causing the stalk to turn white and wither. The method of estimating the damage is simple: you count how many white stalks or rice there are. In a hundred plants, ten or twenty percent of the stalks may be white. In severe cases, when it appears as though the whole crop has been ruined, the actual damage is about thirty percent.
To try to avoid this loss, one field of rice was sprayed with insecticide to kill the stem borers; another field was left untreated. When the results were calculated it turned out that the untreated field with many withered stalks had the higher yield. At first I could not believe it myself and thought it was an experimental error. But the data appeared to be accurate, so I investigated further.
What happened was that by attacking the weaker plants the stem borers produced a kind of thinning effect. The withering of some stems left more room for the rest of the plants. Sunlight was then able to penetrate to the lower leaves. These remaining rice plants grew more strongly as a result, sent up more grain-bearing stalks, and produced more grains to the head than they could have without the thinning. When the density of stalks is too great and insects do not thin out the excess, the plants look healthy enough, but in many cases the harvest is actually lower.
Looking at the many research testing center reports you can find the results of using practically every chemical spray on record. But it is generally not realized that only half of these results are reported. Of course there is no intention of hiding anything, but when the results are published by the chemical