Observations were made of the areas of herbage receiving the faeces of grazing dairy cattle and of the areas and relative palatability of herbage whose growth was alTected by faeces and urine. The average area covered by faeces was 1-i sq. Tt./cow/day. Faeces dropped during grazing had a negligible affect on the utilization of herbage at thai grazing, but each dung-pat probably affected Ihe growth and palaiability of an area of herbage about six times as great at the next grazing. The area of herbage whose growth wasafTecied by urine was equal to that affected by faeces, but unlike faeces, urine improved the palatabilily of the herbage to dairy cows. The dala were used to calculate approximate areas of herbage likely to be afTecied by excreta at ditTerent levels of stocking, and it appeared that excreta return plani nutrients to a given pasture acreage more quickly than some other estimates suggest-

have shown the effect of nitrogenous and mineral fertilizers in maintaining high production from grassland. Most of these experiments were based on mixed swards, in which perennial ryegrass predominated. Simple one grass-one clover leys have increased in popularity, and much interest has been shown in the so-called pedigree or bred strains of grasses. There is little published evidence on the response of these strains and mixtures to fertilizer treatments. It was, therefore, decided to follow earlier studies by comparing the performance of commercial and pedigree strains of the most important species of grass under uniform conditions of cutting and at various levels of fertilizer treatment.Attempts have also been made in previous experiments to assess the efficiency of utilization of fertilizer nitrogen by the grass sward, but it has always been difficult to decide on a control yield since this is so much affected by the nitrogen contribution from clover normally present in the sward. In the present work, therefore, swards containing no clover were studied without fertilizer nitrogen and with two levels of fertilizer nitrogen, and were compared with grass-clover swards so that an assessment could be made of the net contribution of nitrogen from the clover.The experiment was established in 1948 and continued for 2 years in 1949 and 1950 with uniform cutting intervals for all grasses and treatments, the object being to determine the difference between grasses in yield, seasonal productivity, yield response to nitrogen and compatibility with clover. It was considered that in 1949 and 1950 the fixed cutting schedule might have reduced yields on the low fertility treatment by too frequent defoliation, or on the other hand might have reduced the quality of the herbage in the highest fertility treatment because it was not cut often enough. The treatments were continued, therefore, 18 in 1951 and 1952, but for each treatment the grass was cut when it was considered to be a suitable height for grass-drying, irrespective of the condition of the same grass under the other treatments.In 1953 an assessment was made of the residual fertility in the plots of the non-clover treatments, both as grass and when ploughed and cropped with oats. Clover dominance was established in the clover treatments by the end of 1950. In view of the practical importance of the influence of fertilizer nitrogen on clover-dominant swards a subsidiary experiment to study this was started on these swards in 1951 and continued in 1952 and 1953. EXPERIMENTALThe experiment was carried out on a level field of light loam which had been under arable crop for 3 years. A soil analysis made during May 1948, gave the following results: available P 2 O 5 , 8 mg./ 100 g.; available K 2 O, 9 mg./lOO g.; loss on ignition 11 %; pH 5-9. After this soil analysis, ground limestone (48% CaO) was applied at the rate of 1 ton per acre and the land was ploughed. A further 1 ton per acre of ground limestone was applied before the land was ploughed again in early summer; basi...

Six factorial experiments, each lasting 3 years, were carried out to determine the effects of N, P and K on herbage cut five times each year.Clover almost disappeared with the 87 lb. N treatment and none survived with the 174and 348 lb. dressings. N increased the proportions of rye-grass and cocksfoot in the sward. P had no influence on botanical composition. K usually increased the clover content in the absence of, but had practically no effect in the presence of, N.

The paper reports the results for six factorial experiments carried out over a period of 3 years, and designed to measure the effects of nitrogen, phosphate and potash on the yield of dry matter and to determine the effect of nitrogen on the phosphate and potash requirements of grass being cut five times per annum for conservation.Heavy dressings of nitrogen reduced the percentage of dry matter in the fresh herbage, but produced a very large increase in the yield of dry matter. There were quite large variations in the response to this plant food, but 348 lb. N per acre per annum practically doubled the yield and generally the response curves were substantially linear.The response to nitrogen depended on an adequate supply of potash and at five of the centres there were very large interactions between these two nutrients. The need for potash was greatest at the highest nitrogen rate and was much greater in the second and third than in the first year of the experiments.At the highest nitrogen rate some of the responses to potash were very large. The yields of dry matter showed no large or consistent differences between applying 336 lb. K2O in one dressing during the winter months or applying this amount in five equal dressings, one for each cut. The results demonstrated the ability of the soils to supply potash and showed that the regular cutting and removal of herbage, especially if heavy dressings of nitrogen were applied, exhausted the potash reserves in the soil.Phosphate had practically no effect on the yield of dry matter either in the presence or absence of nitrogen.With adequate potash the production of dry matter per lb. of fertilizer nitrogen was practically independent of rate and the overall mean results are between 14·0 and 15·7 lb. In the absence of fertilizer potash there was a very large effect of rate: 15·0 lb. dry matter per acre was produced per lb. N with the 87 lb. N per annum treatment, 13·7 lb. with 174 lb. N and 10·0 lb. with the 348 lb. N treatment.Approximately 70–75% of the annual production was obtained before the end of July. Thus 1 lb. of fertilizer nitrogen produced considerably more dry matter per acre during May, June and July than later in the season.