February i, 1884.] 



THE TROPICAL AGRICULTURIST. 



581 



from his laud ; whether to go on obtaining only a crop 

 every second year, or perhaps two crops in three years, 

 or whether to lay out a larger portion of capital on 

 the land, in the form of manure, so that he may ob- 

 tain a crop every year. With many farmers the question 

 will be simply a matter of calculation, for over a 

 large portion of the colony manure of any kind cannot 

 be obtained unless a considerable expense is incurred. 

 But there is another mode of procedure in the cultiv- 

 ation of green crops to plough into the land, which 

 it is in the power of nearly every one to carry oxit, 

 and although it docs not add to the mineral con- 

 stituents of the soil, nor prevent ultimats impoverish- 

 ment, it is greatly more efficient in the work of chang- 

 ing the insoluble constituents of plants into a condition 

 to be appropriated as plant food. 



The nitrogen that is added to the soil during the 

 time it lies fallow is liable to be washed out by heavy 

 raiDP, drainage water almost invariably carrying off more 

 or less, so that much of what has been gained through 

 chemical action during the season may be washed away 

 and lost should a hea\'y rain occur before the next 

 crop has had time to appropriate it. This danger of 

 loss is entirely obviated by the cultivation of a green 

 crop, which seizes upon the nitrogen as fast as it is 

 formed and retains it for the use of the succeeding 

 crop, ia tte firm of organic compounds, and when 

 the crop is ploughed into the gronnd, where it rapidly 

 undergoes decomposition, the nitrogen is again liberated 

 and ready for the succeeding crop, while the remainder 

 is changed into humus, one of the most valuable con- 

 stituents of soils, exercising a beneficial influence on 

 both the chemical and physical condition of the soil ; 

 for though not in itself of any practical importance 

 as plant food, it serves (says Maclvor) " by dissolving 

 in rain water, to promote the liberation from insoluble 

 combinations of the valuable constituents pi-esent in the 

 soil. But acc<irding to the same authority these are 

 not the only beneticial chemical results brought about 

 by greeu manuring; "the plants in decomposing set 

 free the mineral or ash constituents they drew from 

 the soil in forms of combination more readily available 

 to the succeedmg crop than these were in the state 

 in which they naturally existed in the soil. In addition 

 to thus preparing the mineral constituentsalready present, 

 greeu manuring with deep-rooting plants actually 

 replenishes the surface soil in these substances : food 

 hitherto unavailable to the grain or other crops is 

 drawn up from the subsoil by the deeply penetrating 

 roots of the lupin or clover and brought within reach 

 of the succeeding crops." 



Recurring to the presence of humus in the soil, and 

 its Value as a retainer of nitrogen which exists in the 

 soil chiefly in the form of humus, by tillage and bare 

 fall.jw the humus is oxydised, and the soil loses a portion 

 of its store of nitrogen. Continuous corn cropping with 

 artiticial manures tends in the same direction. On the 

 other hand laying down in grass, the ploughing in of 

 green crops, or the application of farmyard manure in- 

 creases the proportion of humus in the soil ; and although 

 humus may not have the power of combining with the 

 nitrogen of the atmosphere, it is undoubtedly capable 

 of absorbing ammonia, of which the air always con- 

 tains a small amouut, and is thus, apparently, one 

 condition of maintaining fertility. 



It has been proved that the soluble nitrates are formed 

 inoit rapidly in the soil in the end of summer and 

 beginning of autumn, and if a green crop is on the 

 land at the time these nitrates are taken up by the 

 plants and rendered insoluble by entering into other 

 compounds in the substance of the plant, whereas the 

 grain crop?, which come off early, finish their gro\vth 

 bifore tlie lime for the most rapid formation of nitrates 

 has arrived, and, as previously remarked, there is danger 

 that a considerable portion of these nitiatos may lie 

 washed aM ay by heavy rains, which do occasionally 



fall during the autumn months, before the new crops' 

 are in a condition to absorb them. 



Shading the soil is another function of green crops 

 which is by many, both culturists and scientists, con- 

 sidered to be highly beneticial to the land. Indeed 

 ils value has been so long and so commonly recognised 

 as to have passed into the proverb that " Snow U 

 the poor man's manure." ".Science and experiment 

 have show'r," says Professor Knapp, of Towa, **that 

 what is so iieoelicial in winter is even more advant- 

 agt'ous in summer, ami that few things can be more 

 harmful than to denude the soil and allow it thus to 

 remain for a length of time." 



The cultivation of green crops is nature's plan of 

 enriching the soil; we know that the face of the earth 

 has not be^ n always covered with soil capable of pro- 

 ducing either the grass of the field or the trees of 

 the forest, but that the gradTial increase in the number 

 of plants and the fertility of the soil were co-existent, 

 one being the consequence of the otiier, and the com- 

 plete shading of the soil has always been a concomitant 

 of progre.'!F, while wherever the soil remains, or has 

 been made bare, there barrenness prevails. 



Green crops are further beneficial, inasmuch as they 

 are of great assistance in clearing the land of weeds, 

 which m»y be in part smothered by the plants and 

 the remains destroyed when the crop ia ploughed under, 

 without the necessity for the frequent ploughing ^nd 

 scarifying necessary to clear- a foul fallow. 



The choice of the kind of plant to grow for green 

 manuring roust depend upon a variety of circum- 

 stances, such as the nature of the soil, the climate 

 and others, but chiefly of the cost of seed, which, if 

 not very low, might cause a loss iustad of a prolit. 

 Clover, peas and other leguminous plants are highly 

 recommended for the purpos", and where the soil ia 

 of a calcareous nature, tliey are effective both by 

 supplying a large amouut of vegetable matter, and 

 by their deep rooting, especially red clover, bringing 

 up from the subsoil the mineral constituents wnich 

 the roots of wheat or other grain cinnot reach, and 

 depositing them near the surface for the benefit of 

 future crops. The lupin, which belongs to the same 

 natural order, has proved to be an excellent prepar- 

 ation for the grain crop wherever it has received a 

 fair trial ; it is capable of suppressing all kinds of 

 weeds, including sorrell ; it, however, cannot yet he 

 obtained in the colony, but it is one of tho5e plants 

 of which farmers might provide themselves with tlio 

 seed. Rape and White Mustard are perhaps the most 

 commonly grown for the purpose ; they do well ou 

 all soils in tolerable condition, but, if tbe soil ia 

 poor, it is advantageous to further their growth by 

 means of artificial manure. O.ats and rye are also 

 suitable for the purpose. If the former are sown w'ith 

 the first autumn rains, they may be fit; for plough, 

 ing down soon after midwinter, and may be succeeded 

 by a crop of rye, which will be ready in time to 

 admit of being followed by rape, musfa'-d, or some 

 similar crop, or even by a crop of potatoes. Green 

 crops should he ploughed in just as the flower begins 

 to open, with the exception of grain, which is ready 

 a3 soon as it has attained a sutiicient length. It is 

 a common and frequently a profitable practice, to 

 consume a portion of the crop with sheep or other 

 stock, and to carrj' out the practice successfully, the 

 crop should be assi.sted with a portion of artiticial 

 mauure; which will benefit both the stock and the 

 iuoceedihg grain crop. — Leader. 



FLIES AND BUGS. 

 Beetles, insects, roaches, auts, bed-bugs, rats, mice, gop- 

 hers, chipmunks, cleared out by " Rough ou Rats. " B. S. 

 Madon *V Co., Bombay, General Ayents. 



