EFFECT 0¥ MIXKKAL MANTKES i:.'.» 



receives superphosphate only. Willi the coiuplcte minerals 

 a fair crop is grown, averaging over U ton of hav lor the 

 first cut alone, and when the successive ten - vear averages 

 are considered tliere are no signs that the fertility of 

 this plot is decHning, since the production only shows Mieh 

 fluctuations as may be put down to seasons. The reason that 

 the crop on this plot is maintained, although no nitrogen is 

 supplied in the manm-e, lies in the free growth of leguminous 

 plants. It will be seen that, taking the average over the wliole 

 period, the leguminous plants form 24 per cent, of the herbage, 

 and the proportion has increased from year to year. These 

 leguminous plants are not only themselves independent of 

 nitrogen in soil or manure, but by fixing the atmospheric 

 nitrogen and leaving it jjehind in the residues of their dead 

 roots, they provide a supply for the grasses and other plants 

 which cannot of themselves feed on the nitrogen of the air. 

 The predominant leguminous plant is Latf/j/rus j/j-dtc/isi.t, but 

 Red and White Clover are also abundant. A large number 

 of species of grasses are represented on the plot, none of which 

 are specially prominent. Amongst the weeds, Yarrow is 

 very abundant, and there is also a rather large projjortion of 

 Sorrel. The general aspect of the vegetation is shown by the 

 photograph of tm'f, Fig. 20. 



The omission of potash on Plot 8 has caused a very 

 striking difference both in the crop and in the character of the 

 herbage. Tlu average crop has been about one-quarter less 

 over the whole period, and shows a progressive decline in 

 fertility, until at the present time it is little more than half 

 that of Plot 7. The poor results on this plot, as compared 

 with Plot 7, must be put down to its poverty in Iegunn"nous 

 herbage, the development of which seems to depend on a free 

 supply of potash. Of late years the proportion of legiimiiioiis 

 plants on this plot has amounted to al)out one-half of that 

 found on Plot 7, the grasses are about the same, the (lillerciice 

 being made up by an increased amount of weed. The 

 characteristic leguminous j^lant is the Bird's Foot Trefoil, 



