68 AGRICULTURAL STUDENTS' GAZETTE. 



wheat field has been carefully sampled and analysed from time to time, 

 and it is very probable that when the soil at the top and bottom of the 

 field is examined we shall find some increase in the nitrogen, which 

 would probably be due to the action of the leguminous plants ; the 

 soil, however, must have acquired properties which are not to be 

 ascertained by ordinary chemical analysis alone,, and might afford an 

 interesting study for those who investigate the minute organisms which 

 play so important a part in animal and vegetable life. 



I will now describe an experiment very similar to the last, in which 

 a field which had been growing a leguminous crop for a great number 

 of years, was allowed to cover itself with native vegetation. In 1848 

 it was decided to grow continuous crops of beans under circumstances 

 with regard to manure, &c., very similar to the experiments upon 

 wheat ; it was, however, found that this crop when continuously grown 

 could not be depended upon under any system of cultivation, and after 

 more than thirty years of very unsatisfactory results, it was decided to 

 give up the experiment. The unmanured bean land would hardly yield 

 a crop equal to the seed sown. Barley and red clover were then taken, 

 but the barley was much injured by the immense growth of the clover 

 amongst it which yielded large crops during the two following 

 years. A considerable part of the field was then turned into the 

 park for permanent pasture ; but about two acres were fenced off 

 so as to prevent any stock going upon it ; and for the last ten 

 years it has been allowed to grow native vegetation without dis- 

 turbance of any kind. Round three sides of the field there are high 

 hedges with a good many trees growing in them ; on the fourth side 

 iron hurdles separate it from the permanent pasture. I should say that 

 this piece of land is more favourably situated for the growth of a great 

 variety of native vegetation than the wheat field, and yet none has 

 come upon it. The vegetation consists of a few tall, tufted growing 

 grasses ; and near one oak tree there are a few small oak trees due to 

 the unconsumed acorn stores of mice. Along the line of hurdles which 

 separates the bean land from the pasture there is abundance of white 

 clover, but none crosses the border. Nothing can be less interesting 

 than the vegetation of this field, or more remarkable as contrasted with 

 that of the wheat field ; a result which was not anticipated, and which 

 at present remains unexplained. When we sow one half of a field 

 with 'corn and see flocks of birds of all descriptions settled there, while 

 none are to be seen upon the unsown portion, we know that the birds 

 find their food on one part of the field and not on the other ; here we 

 have two fields treated exactly alike for long periods of time ; some 

 portions unmanured, some receiving farm-yard manure, minerals only, 

 nitrates, ammonia, &c. ; the only difference being that one has grown a 

 cereal, the other a leguminous crop ; and yet, when put out of cultivation, 

 in one field great varieties of native vegetation find their appropriate 

 food, while in the other only one is to be found ; we know that the 

 birds are attracted by the corn sown, but what attracts the vegetation ? 

 In our rotation experiments, published last year in the Journal of the 



