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THE AGRICULTUKAL NEWS. 



December 24, 1910. 



FRUITS AND FRUIT TREES. 



GREEN MANURES IN CALIFORNIAN 



ORCHA.RDS. 



The following extracts i-ehiting to the use of green 

 manures in orchards, in t'alifornia, ;ire taken Ironi 

 Bulletin No. 190 of the Bureau of Plant Industry, 

 United States Department of Agriculture (October 

 1910): — 



GENERAL. The u.se of green manure crop.s for the main- 

 tenance of soil fertility i.s one of the oldest of agricultural 

 practices. In California, such crops have been used in a limit- 

 ed way for a long tinip, yet it is only within recent years that 

 their practical value has liecoiue fully recognized. The grow- 

 ing of these crops has attained its greatest development in the 

 citrus orchards of the southern part of the State, wliere they 

 have been longest used. 



For a number of years the Bureau rif Plant Industry has 

 been working to secure l)etter crops for green manuring than 

 the ones now used, and to aid in the demonstration of the 

 adaptability of the ones now being grown. The Agricultural 

 Experiment Station of the University of California has also 

 done extensive work in demonstrating the value of the various 

 green manure crops in that State. 



In California, the work of the Bureau of I'lant Industry 

 has been carried on in co-operation with orchardists and 

 farmers throughout the various sections, and at the United 

 States Plant Introduction Garden at Chico, where exten- 

 sive tests have been made. This work has clearly indicated 

 the superiority of certain crops over others and their adajita- 

 tion for varying [lurposes and conditions. 



DESIR.-VBLE I ■H.AR.\CTEl;S OF .\ OREEN M.XNURH. Xo OUC 



plant possesses all the desirable qualities of an ideal green 

 manure crop. However, in the various crops used for such 

 purposes, practically all the desirable qualities are represented, 

 though varying in degree. The conditions under which a green 

 manure is to be grown determine to some extent whether 

 a certain quality is desiralile or olijectionable, and must be 

 taken into consideration in selecting the best crop to grow. 



A green manure crop should be a legume wherever 

 possible, in order to obtain the addition of nitrogen to the 

 soil. It is also necessary that a good growth be made, in 

 order to have a large quantity of organic matter to turn under 

 and incorporate with the soil. With good growth should 

 be a heavy development of nodules on the roots, as this is 

 believed to indicate great ability to fix atmospheric nitrogen. 



The quality of li'^ing able to stand trampling with 

 a niinimumof injury is very important where the crop will be 

 subject to sucli injniy. as in the case in citrus orchards where 

 I he picking of fruit takes place while the green manure crop 

 is yet growing. U^irightness and non-twining stems are also 

 desirable where an ordinary mould-board plough is depended 

 U|ion for turning under the crop. However, if a disc 

 plougii is used, or tht crop is worked in with an ordinary disc 

 harrov.-, this does not make so much difference; and where the 

 growth is not allowed to become too rank, little difficulty is 

 experienced in ploughing it under. 



The texture of the stem should be such as to decompose 

 readily Practic-illy all crops, however, if turnedunder at 

 the right stage of growth, decay readily. Thus, the question 

 of decomposition is one of turning under the crop at the 

 right time, rather than one of selecting a crop that will decay 

 readily. 



riiiit the cost of agi-cen manure may not be too great, it 

 is necessary that the pi'ice of seed be reasonable as compared 

 with the results to be obtained, 



TURNING UNDER cREEN M.VNURES. In turning Under 

 a green manure crop the common mould-board plough, the 

 disc plough, or the disc harrow is used. In using the first, 

 a sharp coulter is attached, and where the vine growth is 

 heavy a chain is also used. Sometimes the land is run over 

 once with a disc harrow before |>Ioughing. This enables 

 a heavy growth to be more completely turned under. During 

 the past few years the disc [ilough has been very generally 

 u.sed, and for turning under a lieavy vine growth it works 

 more satisfactorily than the mould-board plough. 



After ploughing under a green manure crop the laud is 

 harrowed, and as the crop decays cultivation is given. This 

 at first is shallow, so as not to bring the vines to the surface, 

 V>ut latijr a deeper cultivation is given. 



In sections having a very open soil or a .sandy loam, the 

 disc harrow has been used very successfully in turning under 

 a green manure crop. 'I'he use of this harrow has bet-n taken 

 up with the idea that fewer surface-feeding roots of the trees 

 are disturbed by its use than is the case with the plough, for 

 which reason it is thought liy many to be more desirable. In 

 working a green manure crop into the soil with a disc harrow, 

 four discings are usually required, each discing, where the 

 planting of the orchard will permit, being made at an angle 



