The intensive production of herbage for crop-drying Part VI. A study of the effect of intensive nitrogen fertilizer treatment on species and strains of grass, grown alone and with white clover

Abstract

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...

Nitrogenous fertilizers and the production of crops and grass

“…This was found by Watkin (1954) at Wye and by Holmes & MacLusky (1955) at the Hannah Dairy Research Institute. On the other hand, Holmes (19546) found on a predominantly grassy sward an almost linear response to nitrogen up to an application of 300 lb./acre/annum.…”

“…If this is so, the most efficient use of nitrogen is obtained by concentrating heavy dressings on a proportion of the grassland acreage and encouraging clover on the remaining area rather than using small dressings over the whole acreage as is the common practice in this country. Watkin's data clearly supported this conclusion but it is not wholly Holmes & MacLusky, 1955). I n Fig.…”

The Effect of White Clover and Nitrogenous Fertilizer on the Production of a Sward

“…This is in general agreement with results obtained elsewhere in the United Kingdom and in the U.S.A. (Table 3). It is interesting to note that the value was so high with cocksfoot, since Holmes and Maclusky (12) found that cocksfoot responds better to N and is not so compatible with white clover as are other species; the recent report by Herriott and Wells (10) supports this.…”

Studies on the cutting management of grass-clover swards. I. The effect of varying the closeness of cutting on the yields from an established grass-clover sward

“…Holmes & MacLusky, 1955;Walker, Adams & Orchiston, 1953;. However, some of the effects of the nitrogen treatments compared should be discussed here.…”

“…The Hannah Dairy Research Institute, Ayr (With Two Text-figures) Experiments reported by Holmes (1948Holmes ( , 1949Holmes ( , 1951a and by Holmes & MacLusky (1954, 1955 have provided much valuable information on the fertilizer aspects of the intensive production of herbage for crop drying. A fairly standard management was applied throughout these experiments, and little attention was paid to the possible modifying influence of cutting management systems on the response of the grass-clover sward to fertilizer treatment.…”