LUCERNE MEMS. 81 



Manuring Lucerne. 



At the Government Experimental Station at -Robertson, some 

 interesting experiments in testing the effect of manures on lucerne 

 are being carried on. 



In the Karroo it is generally assumed that owing to the rich- 

 ness of the soil there is no occasion to manure it, and old lucerne 

 lands are known to continue to yield prolific crops after many years 

 of repeated cuttings. The result of the experiments, however, goes 

 to show that, marvellous as is the return from an acre of established 

 lucerne, the yield may be greatly increased by the addition of 

 suitable manure. 



At Robertson a plot of lucerne was given 800 Its. of super 

 phosphate per acre. The strength of the dressing was what is 

 known as 33-35, that is it contained that percentage of phosphate. 

 The cost was 4 10s. per ton or 1 16s. per acre. The manure 

 was applied ear]y in the season. Oft' this plot the yield was five 

 tons more than off the unmanured area, and this at 5 per ton gave 

 a return of 25 for an outlay of 1 16s. on manure, or hay was 

 produced at under 8s. per ton. The actual figures are : Total 

 weight of four cuttings, no manure and 800 Ibs. suoer sulphate, 

 5,320 Ibs. and 17,20'J Ibs. lucerne hay per acre respectively. 



But another most important effect is produced by manuring 

 with suitable manures. The more luxuriant the growth of lucerne, 

 the more certainly are the weeds smothered, and the kweek 

 grass that so infests many lucerne lands has no chance in getting 

 established. Those who have not studied the effect of manures 

 might naturally infer that what was good for the lucerne was good 

 for the kweek, but it is not so. Different orders of plants require dif- 

 ferent food, and whilst grasses (graminia) require nitrogen, lucerne 

 and other leguminous crops (tcguminosa) by the aid of bacteria fix 

 atmospheric nitrogen and require chiefly phosphates, potash and 

 lime ; when supplied with this food they grow so much more rapidly 

 and luxuriantly than the grass, that the latter gets no chance. 



In the wide field of agriculture there is nothing more danger- 

 ous than to generalize from a particular. The chances are that 

 most of our Karoo soils contain sufficient potash and lime to grow 

 most abundant crops of lucerne, yet is is conceivable that some 

 potassic manure, used along with super phosphate, might give 

 profitable returns. In some cases, too, basic slag might be better 

 than super phosphate, and doubtless in many instances smaller 

 dressings than 800 Ibs. per acre would be more remunerative. All 

 these points, however, can only be ascertained for each farm by 

 experiments conducted thereon. The general principles of manuring 

 are perfectly well known to science, but their application to parti- 

 cular cases can be ascertained only by experiments or actual tests 

 in the particular case. 



We trust some lucerne growers will also try experiments 

 for themselves and let us have the results of their experience. The 



