TEUCK FARMING. 

 Eeduced to weiglit, 1 ton of fresh cow-pea vines contains : 



599 



Before enumerating tbe benefits to the soil itself from the ultimately 

 resulting humus, those must he mentioned accruing to it from the dense 

 shade of a mass of growing cow-pea Aines, and from their action after- 

 wards during the process of fermentation and decay beneath its surface. 



Boussingault examined snow which had remained on the soil of a gar- 

 den for thirty-six hours and that which had just fallen upon an adjoin- 

 ing stone terrace. The former contained ten times as much ammonia 

 as the latter, the mulch of snow having interrupted and absorbed the 

 ammoniacal emanations from the soil. The ammonia of the soil is con- 

 stantly fluctuating. In dry weather it rises, dissolved in capillary 

 water, to the surface, and is partly lost into the atmosphere during the 

 process of evaporation, especially when the soil is bare of vegetation 

 or otherwise is uncovered. In wet weather it is washed down deeper 

 into the soil, but fortunately not beyond the reach of roots, as generally 

 below G feet there is no trace of it. The dense covering of j)ea vines 

 acts like the mulch of snow, keeping the surface moist and interrupt- 

 ing the evaporation and loss of ammonia. 



Sir J. B. Lawes examined the drain-water at Rothamsted and found 



that it took from a field kept bare of vegetation at the rate of 40 pounds 



per acre per annum ; from a field of wheat upon which no weeds grew 



after the harvest 25 pounds, and from a field upon which grass seed 



had been sown with the wheat and continued to grow in the stubble 



only 5 pounds. 



Pounds of nitrogen washed aicay,per acre. 



Pounds. 



From a soil witliout vegetation 40 



From a soil -with wheat, 15 pounds retained by wheat 25 



From a soil with "wheat and grasses, 15 pounds retained by wheat, 25 j)ounds 



by growing grasses 5 



Having analyzed the rain-water that had fallen at Rothamsted during 

 the period of the experiment, he found it had not contained as much 

 nitrogen to the acre as was discovered in the drain-water. 



The fact, however, of greatest importance to our subject of green 

 manuring which he ascertained was, thiit daring the fall tlie anion i:r 

 of ammonia carried away in drain-water was greater than at any otlici' 

 time of the year. It is just at this season and during winter that the 

 soil of the truck, as well as other, farmers should be well covered with 

 vegetation. The land of the truck farmers near cities is so well m;i- 

 nured that the growth of grass answers this purpose ; but, as the stnb- 

 ble decays much more slowly than pea-vines, plowed under, either green 

 or dry, the latter even here would be preferable in not requiring to be 

 plowed under so early, thus giving the soil the benefit of a longer mulch. 



At a distance from towns, however, where less manure having been 

 used, the surface of the often yet unrenovated soil' is rarely sufficiently 



