106 THE SOIL OF THE FARM. 



That the water passing through these gauges is much 

 richer in nitrogen than the rain which falls upon them. 

 (2. ) That it is richer in nitrogen in the autumn than at 

 any other time of the year. (3.) That the drainage 

 water collected in another field, where a crop of wheat 

 was in luxurious growth, contained no nitric acid at all, 

 and we have before us a basis from which some very im- 

 portant conclusions can be drawn. 



We learn that the most important ingredient of the 

 food of all plants, as also the most expensive when used 

 artificially, is continually produced in our soils, is con- 

 tinually moving about, continually being taken up by 

 vegetation, and continually being washed away and lost. 

 Such being the case, it follows as a necessary consequence 

 that the amount of nitrogen that analysis has proved to 

 be contained in our crojDS is not a correct measure of the 

 exhaustion of this substance, but we must add to it the 

 amount of nitric acid which is lost from the crop being 

 unable to take it up from one cause or another. I will 

 endeavor to explain my meaning by an illustration taken 

 from an ordinary operation in farming. A farmer sows 

 two fields, one with wheat only, one with wheat and 

 timothy, clover, rye-grass, or an assortment of these 

 plants. The wheat is sown before the seeds, and takes 

 the largest share of the light and food; soon after bloom- 

 ing the wheat ceases to gather food from the soil, and in 

 the early summer, the crop being ripe, is carried away. 

 The seeds are thus relieved from a powerful antagonist, 

 and, having complete possession of the soil, continue to 

 grow both above and below it until they are stopped by 

 frost; even then it is probable that tlie roots, which are 

 beneath the region of frost, grow and collect food. 



Assuming the wheat field not sown with grass to be 

 without weeds at the time of harvest, and afterwards (a 

 very improbal^le assumption, I admit,) it would resemble 

 the soil of my drain gauges, and be subject to the same 



