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Cover Crops OR CLEAN CULTURE. 
are : we methods of handling fruit land which have partisans or 
detractors. The objection to cover crops is that, if the amount of 
moisture in the ground is not sufficient for both cover crop and 
fruit trees, the latter suffer. Cover crops also, unless kept under 
control with the aid of field implements, may hamper cultivation 
in the early summer when fruit land should be clean. 
Clean culture, if carried out too scrupulously, leads to gradual 
impoverishment of the soil. It cannot produce good results in- 
definitely, particularly where the soil is light and friable, when the 
leaching of nitrates and other available plant food takes place 
during periods of excessive rainfall, when the trees are dormant, 
in the wet winter months. 
Desirable cover crops are those which make a good growth 
during the winter season and which can readily be disposed of in 
the spring, when clean cultivation is the established rule. 
Of cover crops there are two classes—nitrogenous collectors, 
such as the leguminous plants: trefoils, field and cow peas, beans, 
vetches, lupines, etc.; and nitrogenous consumers, such as grasses 
and other cereals, rape, ete., which only restore to the soil what 
they have withdrawn but leave vegetable fibre and humus, which 
benefit the physical conditions of the ground. 
They all improve the physical conditions of the ground, break- 
ing up clay soil and making sandy soil more compact. They im- 
prove the water-holding capacity of the soil by adding humus to 
it. They remove and dry up excessively damp soil, by the agency 
of their leaves. On sloppy ground they bind the soil and check 
washaways during periods of heavy rain. 
Cover crops also improve the fertility of the soil by preventing 
the leaching of nitrates and available plant food as already men- 
tioned, promote nitrification, add plant food by fixing nitrogen 
from the air into the root nodules as in the case of leguminous 
crops, or by searching for plant food at depths and bringing it up 
closer to the surface, where it is reached by the feeding rootlets 
of the crop. It also breaks up plant food in the ground and makes 
it available. A fair leguminous crop sown amongst trees or vines 
when ploughed in when blossoming starts, adds pretty well 100lbs. 
of nitrogen per acre to the ground. 
MuucHine 
is often resorted to in nurseries and places where it is not always 
possible to give to the trees the amount of attention they require. 
It acts as a screen that prevents the rapid evaporation of the 
moisture from the ground, keeps the surface cool; but, on the other 
hand, it often harbours insect pests, gives to the place an untidy 
appearance, favours an undesirable growth of the young thread- 
like rootlets of the tree close up to the surface of the ground: so 
