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Directives were drafted for different aspects of wind protection and shelterbelts. An analysis was made of the effects of wind and protection on crop yields, and the establishment of shelterbelts was discussed. The respective increases in yield of bean and maize crops, in the protected zone of the windbreak in the experimental field, were only 12 and 17 % in 1960 by accumulation of moisture behind the windbreak, through excessive rainfall and partial rotting of the bean plants. For maize a height and width of windbreak of 2 m and 6 m, respectively, was too small.In a wind tunnel in a greenhouse the yield of bean seed was 67 % higher in the protected zone. In pot experiments the respective yields of bean seed and dry weight of maize plants increased by 28 % and 11 %.The optimum shelterbelt design was estimated by models in a wind tunnel. Shelterbelts mainly improve temperature, transpiration rate and soil moisture conservation, and also prevent mechanical injury of plants. This results in an increased photosynthetic surface and a better relation shoot/root. The Shamin shelterbelt model proved best for large areas, the Ali and Usman models for smaller ones. The planning, administration and management of shelterbelts were discussed.

Directives were drafted for different aspects of wind protection and shelterbelts. An analysis was made of the effects of wind and protection on crop yields, and the establishment of shelterbelts was discussed. The respective increases in yield of bean and maize crops, in the protected zone of the windbreak in the experimental field, were only 12 and 17 % in 1960 by accumulation of moisture behind the windbreak, through excessive rainfall and partial rotting of the bean plants. For maize a height and width of windbreak of 2 m and 6 m, respectively, was too small.In a wind tunnel in a greenhouse the yield of bean seed was 67 % higher in the protected zone. In pot experiments the respective yields of bean seed and dry weight of maize plants increased by 28 % and 11 %.The optimum shelterbelt design was estimated by models in a wind tunnel. Shelterbelts mainly improve temperature, transpiration rate and soil moisture conservation, and also prevent mechanical injury of plants. This results in an increased photosynthetic surface and a better relation shoot/root. The Shamin shelterbelt model proved best for large areas, the Ali and Usman models for smaller ones. The planning, administration and management of shelterbelts were discussed.

The use of wind-breaks in orchards was studied. Similar observations were carried out on early horticultural crops such as strawberry and potato, and on field crops such as rye, wheat, sugar-beet, and maize.Net profits of 10-45 % with apple and 12-162 % with pear were calculated, if the wind-breaks were 4-6 h away (h = height of the wind-break). The analysis showed that wind-breaking had an important influence on fruit-setting. Higher mean temperature and humidity in sheltered places may favour pollination and fertilization. Therefore, the recommendation to plant more wind-breaks than usual should be accompanied by advice on planting of wind-break trees coming into leaf before blossom time.Strawberries yielded significantly more and were much more profitable in sheltered areas. With early potato, higher revenues were obtained only by promoting earliness, perhaps through 'hothouse' conditions in the sheltered zone.Smaller increases in yield were found for field crops in a zone of nearby 10 h away from the wind-break. ITBON studie

Overzicht samengesteld door Itbon, Arnhem.

The use of wind-breaks in orchards was studied. Similar observations were carried out on early horticultural crops such as strawberry and potato, and on field crops such as rye, wheat, sugar-beet, and maize.Net profits of 10-45 % with apple and 12-162 % with pear were calculated, if the wind-breaks were 4-6 h away (h = height of the wind-break). The analysis showed that wind-breaking had an important influence on fruit-setting. Higher mean temperature and humidity in sheltered places may favour pollination and fertilization. Therefore, the recommendation to plant more wind-breaks than usual should be accompanied by advice on planting of wind-break trees coming into leaf before blossom time.Strawberries yielded significantly more and were much more profitable in sheltered areas. With early potato, higher revenues were obtained only by promoting earliness, perhaps through 'hothouse' conditions in the sheltered zone.Smaller increases in yield were found for field crops in a zone of nearby 10 h away from the wind-break.