28 



CULTIVATION EXPERIMENTS. 



Another method by which the soil conditions may be improved 

 for the plant is to increase the depth of soil over which the roots 

 may range. There are some very old Rotharnsted experiments on 

 the subject. In 1849 the Rev. S. Smith, of Lois Weedon, North- 

 amptonshire, attempted to prove that trenching could profitably be 

 undertaken for wheat cultivation. Trenched plots were therefore 

 laid out for wheat in Hoos Field, the method being to bring up the 

 subsoil and bury the top soil. No increase in crop was observed, 

 however. More recently (1909) the experiment was repeated with 

 fruit trees, the trenching being done on the modern method in which 

 the subsoil is kept below and the top soil kept on top. No evidence 

 could be obtained that trenching had any effect either on the growth 

 of the trees, or on the soil moisture or nitrates. Now trenching is 

 not a farm operation, but it is closely related to subsoiling which is 

 usually considered valuable, and in order to clear up the problem 

 some plots have been laid out to test the effect of subsoiling : this 

 year potatoes were grown on them and showed consistent increases 

 in crop. Mr. F. J. Gurney kindly gave us the implement, which 

 worked very well, breaking up the subsoil with a minimum expendi- 

 ture of labour. 



Another experiment has been started on the methods of sowing 

 wheat after potatoes. When the digger has finished its work in 

 autumn the soil is left in a beautifully fine tilth eminently suitable 

 for the nitrification processes. How can this best be utilised ? 

 The field has been divided into five strips : in one the wheat has 

 been drilled shallow, ploughed in, and harrowed ; in another it was 

 broadcasted, ploughed in, and harrowed ; on the third the wheat was 

 drilled on the surface left by the digger, and put in as deeply as the 

 soil allowed, there being no ploughing or other preparation ; the 

 fourth was ploughed and then drilled in the usual way ; the fifth 

 was ploughed and broadcasted. The first two strips look the best 

 and lay dry through the heavy December rains of 1914 : the third 

 has become badly beaten down by the rain, the fineness of the tilth 

 causing the soil to run together very much, a result that was also 

 obtained last year in similar circumstances : the other two are inter- 

 mediate. 



It is proposed to extend these cultivation experiments, for 

 probably less is .known about the cultivation processes than about 

 any other branch of soil treatment. Before designing any proper 

 set of experiments, however, it is necessary to know what cultivation 

 does. A series of laboratory experiments is already in hand to 

 study the air, water and temperature relationships of the soil, which 

 are known to be affected by cultivation, and it hoped to get some 

 information about that remarkably intricate subject, the texture of 

 the soil. When these are more advanced it will become possible to 

 evolve some scheme of tillage experiments to examine such 

 problems as the difference between a "fresh" and "stale" furrow, 

 which are known to be of practical importance, but which have not 

 received the attention they deserve from experimenters, and indeed 

 cannot until they have been more systematically studied. 



