Ixxiv PROCEEDINGS, 



leaves from fhe atmosplaere, but that it has now been ascertained 

 that it is only their roots which absorb it, showing the great 

 importance of a supply of nitrogenous plant-food in the soil. The 

 difference between cropped and uncropped soil in relation to their 

 water-holding power was pointed out, and also the difference 

 between plants supplied with and without nitrogenous maniire. 



Mr. Willis then showed how leguminous plants grown in rotation 

 increased the fertility of the soil, but if grown year after year 

 impoverished it. In Hoos Field red clover was sown twelve times 

 in 29 years, and failed eight times out of the last ten trials. Thus, 

 when sown frequently on the same land there was almost uniform 

 failure, practically no crop being obtained after the first few years. 

 ■In 1878 various leguminous plants of different habits of growth, 

 and different character and range of roots, were sown on clover- 

 exhausted land. Eed clover still failed, but the weakly-rooted 

 white clover, which had not been sown on the land for many years, 

 did well, and the deeper-rooted vetch better still, while the very 

 strong and deeply-rooted lucern did remarkably well. The general 

 result of these experiments was to show that when various leguminous 

 plants were sown where red clover had failed, they grew luxuriantly 

 and absorbed larger, and in some cases very large, amounts of 

 nitrogen. The more clover, also, that can be got to grow, the 

 bigger will the succeeding wheat-crop be ; but wheat was seen 

 to be growing best of all after lucern, the roots of which go down 

 ten feet from the surface and bring a great amount of nitrogen 

 from the subsoil into the surface-soil. Not being exhausted by 

 the crop of lucern, it is thus brought within the range of assimilation 

 of tlie roots of the wheat. 



With regard to permanent meadow-land, Mr. Willis stated that 

 the better the pasture the more can the grasses be forced, but 

 that if too much manure be put on, the coarser qualities of grass 

 are encouraged and the finer grasses and clovers die out. This is 

 evidently the result of a struggle for existence, the coarser grasses 

 having greater assimilative powers than the finer, and the latter 

 being crushed out the general crop loses in nutritive value. 



Some results of experiments with Swedish turnips were mentioned, 

 and diagrams illustrating them were shown in the laboratory. On 

 unmanured land the yield was 8| cwt. per annum per acre, with 

 mineral manure 11 tons 61 cwt., and with both mineral and 

 nitrogenous manure 24 tons 18 cwt., showing the great value 

 of a supply of nitrogen. 



The rain-gauges and percolation-gauges were also examined, and 

 Mr. Willis stated that the large rain-gauge, which has an area 

 of one-thousandth of an acre, collects from impurities (smoke, etc.) 

 in the air 5 lbs. of nitrogen per annum. There are two other 

 rain-gauges, one with a receiving area 5 inches in diameter and 

 the other 8 inches. The three percolation-gauges are of the same 

 area as the large rain-gauge, and they have a depth of soil of 

 20 inches, 40 inches, and 60 inches. The surface of the soil is 

 kept quite free from vegetation, their chief purpose being to show 



