282 Journal of the Department of Agriculture. — Sept., 1922. 



Green Manure. 



Harnsmltii, (Jiaiiye Free State. — What is the best crop for green 

 iiiauure? 



(lien, Scliool of Af/ricidture replies : The best eroj) for green 

 nuinurc depends on the method of green manuring adopted. If the 

 crop is to be eaten oft' by stock or made into hay, tlie suitability of 

 the crop chosen for these purposes should be inainlj^ considered, a 

 mixture of a legume, such as cowpeas, with Sudan grass or maize 

 preferably, being used. If, however, the whole crop is to be ploughed 

 in, the bulk of green material produced is the main consideration. 



For the reason that legumes, i^rovided they form nodules, add 

 nitrogen to the soil, it is usually recommended that a legume be used 

 for green manuring purposes. Our soils, however, usually do not 

 respond profitably to nitrogenous manuring, and the addition of 

 nitrogen to the soil by the green-manue crop is probably not so 

 important as the addition of humus. Very few experiments on green 

 manuring have been carried out in South Africa, but in countries 

 where the crops do respond to nitrogen, leguminous crops, when 

 used as green manure, have given as good a return in the following 

 crop as rape and mustard and other crops. 



Feeding Value of Cotton-seed Cake. 



Bethlehem, Orange Free State. — Please give me some informa- 

 tion about cotton seed for feeding to dairy cows? 



Glen School of Agriculture replies : Cotton seed is usually 

 obtained in the form of cake or meal for feeding purposes. Cotton- 

 seed cake contains the following percentages of digestible 

 nutrients: Crude protein, 21.1; carbohydrate, 33.2; fat, 7.4 It is 

 a valuable nitrogenous concentrate for dairy cows. Though it is not 

 very palatable, cattle soon take to it. It is ])est to mix it with the 

 other feeds given. The amount to feed is from 2-3 pounds daily. 

 It has a costive tendency, and should therefore be fed along with 

 laxative feeds, such as bran, silage, and roots. It should not be fed 

 to cows shortly before calving. 



Purity of Vegetable Seeds. 



Kiiiibcrley. — Why cannot vegetable seeds — especially cabbage 

 and cauliflower — purchased from the same seedsmen year after year 

 be relied on. 



Glen Scliool of Af/riculture replies: The fault lies in bad selec- 

 tion of plants for seed production, or more probably to no selection 

 at all. Cabbages and cauliflowers are liable to cross-pollinate, and 

 if several varieties are grown near each other the result will be that 

 the seed will be impure. The seedsmen should practise severe rogu- 

 ing, and the farmers should obtain their seeds from reliable growers, 

 and cease to send their orders to seedsmen on whose seed they cannot 

 rely. 



