36 HORTICULTURE, FORESTRY, FLORICULTURE 



comparatively early ; in dry seasons, rather later sowing is best. As 

 a usual thing it is sown between July 15 and August 1. In a season 

 of drought during the early part of the season the probabilities of 

 late growth are quite as great as when June and July have been 

 rainy months. It is well, therefore, to have the seed in the ground 

 ready to begin growth as soon as soil moisture conditions will permit. 



Another important function of the cover crop is to add vege- 

 table matter to the soil. Without the cover crop the orchard soil 

 would soon become depleted of its vegetable matter which would de- 

 stroy its tilth and make the plant food much less readily available, 

 unless considerable quantities of barnyard manure are applied. An 

 ideal cover crop then should produce considerable vegetable matter. 

 In order to do this the importance of having it ready to begin growth 

 following a drought in July or August is apparent. Rapid growing 

 crops are usually preferable to slow growers, although at times for 

 special purposes the slow growing crop may be more advantageous. 



Cover Crops as Plant Food Suppliers. Cover crops may be 

 made to serve the purpose of increasing plant food in the soil. Not 

 all crops used for covers are able to do this. Only leguminous crops 

 such as clover, peas, and vetch are capable of adding plant food, and 

 these only nitrogen. The leguminous cover crops, however, are a 

 valuable asset in keeping up the fertility of the orchard. If used too 

 continuously it may prove detrimental for excessive nitrogen tends to 

 cause excessive wood growth at the expense of fruit produc- 

 tion. It also favors late growth, and in this way may result in con- 

 siderable winter top-killing. Because of these unfavorable conditions 

 which are likely to arise, it is a good plan to practice rotation of cover 

 crops using leguminous crops on average soils, not more than two out 

 of three successive years. 



Hardy and Non-Hardy Cover Crops. In addition to being 

 divided into food supplying and non-food supplying, cover crops are 

 also classified as hardy and non-hardy or tender crops. The hardy 

 crops live over winter and make some growth in the spring thus in- 

 creasing the vegetable matter returned to the soil. They may or may 

 not be efficient in holding the snow or preventing deep freezing. 

 Hairy vetch, although a hardy crop, is usually less efficient in these 

 respects than is oats, which is non-hardy, but which stands up well 

 after frost. 



In the food-supplying, hardy group of cover crops are hairy 

 vetch and crimson clover, the latter of which can only be considered 

 half hardy in Wisconsin. Of the tender food-suppliers, we have field 

 peas and soy beans. Of the hardy non-food-supplying class, the most 

 important is rye, but wheat is occasionally used. The increased cost 

 of the seed, and the fact that the character of its growth is much the 

 same as rye, makes the latter more in favor. 



Of the non-food-supplying tender crops, oats, millet, turnips, 

 and rutabagas are the most used. The two latter might be placed in 

 a class by themselves due to the fact that they have tender tops 

 which kill back with the frost, but roots which live over winter and 

 produce growth the following season. It is not necessary that each 



