158 Journal of Agriculture. [10 March, 1910. 



ORCHARD STUDIES. 



I. GREEN MANURING. 



E. E. Pescott, Principal, School of Horticulture, Burnley. 



The system of green manuring, or as it is called in America, the system 

 of growing co\er crops, because the crops coA^er the ground at a time when 

 it is otherwise bare of foreign growths, is one that should commend itself 

 to every orchardisc, who desires tO' perpetuate, or to continue as long as 

 possible, the fruiting abilities of his trees. To do this, the grower must 

 decide that his soil shall never become exhausted, or " tree sick." When a 

 tree has been growing, and of course in the one place, for a number of years, 

 it can easily be understood that it has removed from the soil a very large 

 amount of the constituents necessary for its nutriment and sustenance. 

 Thus the soil becomes somewhat exhausted, and perhaps depleted of the 

 particular food that the tree requires ; and the tree has then continually 

 to struggle against very adverse circumstances ; and so it is not easily 

 possible for it to grow, to remain vigorO'US, and to regularly produce fruit. 

 The fruit-grower should look upon his land as his fixed bank deposit, and 

 the tree as the interest producer. So long as the trees are not drawing upon 

 the soil to reduce its value, then they are doing well ; but every means 

 must be taken so as to perpetually keep the soil as near to its original 

 state of productiveness as possible, or to improve this condition. Thus, a 

 judicious system of manuring comes into operation, and it is with the work 

 of green manuring that we are now immediately concerned. 



In a few words, green manuring consists of growing a crop of plants, 

 preferably plants of a leguminous nature, in the late summer, and, when 

 the crop is in full flower, ploughing it into the soil, there to rot and add 

 to the amount of humus already in the soil, ultimatelv becoming a valu- 

 able plant food. A large variety of plants may be used for this purpose, 

 but those of a leguminous or pod-bearing character are by far the most 

 valuable. These plants possess the ability to gather atmospheric nitrogen 

 and store it up, especially in the nodules which are so prevalent upon their 

 roots. Thus, when the plants have been turned in by the plough, the 

 garnered nitrogen becomes readily available as a food supply for the trees. 

 The leguminous plants are thus a nitrogen factory, collecting, storing, and 

 ultimately dispersing one of the most necessary and valuable of plant 

 foods. Of course, nitrogen mav be added to the soil bv means of nitro- 

 genous chemical fertilizers ; but it is the addition of humus as a result of 

 the decay of the green manure, that is so valuable, not only as a manure, 

 but as an amelioration of undesirable soil conditions. American calcu- 

 lators have estimated that the world's annual expenditure in nitrogenous 

 manures is aboiit 25,000.000 pounds sterling; and it is stated 

 by them that over every acre of the world's surface there is as much 

 nitrogen in the air as would replace the total quantity used, assuming 

 that it be utilized in the form of green manuring by growing leguminous 

 cover crops. The crop of leguminous plants is sown broadcast or drilled 

 in the orchard in earh autumn, March for preference. The plants thus 

 obtain all the advantages of any early rains, and should reach a fairly 

 advanced stage before the frosts and cold weather of winter arrest their 

 further development. In spring, the plants start into growth again, and 

 are soon in full flower. The crop is then rolled, and ploughed in. 



Various legumes are grown, chiefly vetches, tares, various species of 

 beans, lupins, cow peas, partridge peas, and field peas. The last-named 

 is the variety that is more grown than others. 



