682 ANNUAL. REPORT OF THE Off. Doc. 



"If all conditions are favorable as to rainfall and temperature, the 

 linmus problem is not so important, but if it is expected to carry a 

 crop successfully through a season of extreme drought, as was the 

 summer of 1900, the soil must be abundantly eup[)lied with humus, 

 or otherwise it will part with its moisture and the crop will suffer. 

 Intensive tillage for best results through a series of years must be 

 accompanied with the use of farm manures, or of green manuring. 

 This is especially true of potatoes where best results are secured in a 

 moist, cool soil. Abundance of humus favors both these conditions." 



Kotted organic matter performs in the soil the double office of 

 improving physical condition so that moisture may be held, air be 

 admitted and plant roots be developed, and of furnishing plant food. 

 Sources of such matter will be considered in their two-fold capacity. 



Legumes. — Clover will fit land for potato-growing more completely 

 than any other one plant within my knowledge. Its roots run deep 

 and are bulky. Their habit of growth secures a fine division of clay- 

 ey land, penetrating every cubic inch with fibres, and thus producing 

 the physical condition of soil so grateful to the potato. We incline 

 to look upon clover only as a fertilizing plaut, and as such it stands 

 pre-eminent in the sections adapted to its growth, but it is a safe 

 statement that in a rotation of crops which includes clover and po 

 tatoes, the effect of clover upon the physical condition of the soil 

 gives to this renovating crop half of its value. Such statement does 

 not minimize its fertilizing value, w^hich is unexcelled, but calls at- 

 tention to another value in it often underrated. 



As a purveyor of plant food, clover is first among plants. It feeds 

 upon the free nitrogen of the air through bacteria that live upon 

 its roots and serve it while living upon it, and tihrough deep-running 

 roots the clover feeds in the sub-soil where there usually is a great 

 wealth of fertility. But clover has a way of failing. Or we may 

 have lacked foresight, and there is not time to grow the clover before 

 a crop of potatoes is wanted from a certain field. 



There are other legumes of great value. Living near the southern 

 border of our northern States, the writer has found it profitable to 

 grow many acres of cow peas for plowing down for potatoes. The 

 southern pea has its northern limitations, failing to make as luxu- 

 riant growth north of the fortieth parallel of latitude as it does in 

 the friendly heat of the south. But it makes a good root growth 

 and a fair am<^nint of vine that give a rich humus, and it adds to the 

 supply of soil nitrogen after the manner of clover. The soja bean is 

 another renovating crop of value, growing quickly and providing a 

 good supply of humus. 



Other Sods. — A timothy sod will give good results when handled 

 intelligently . Bearing in mind the need of the potato plant for thor- 

 oughly rotted organic matter, we may see that timothy can be made 



