The effects of a wide range of nitrogen rates on some chemical constituents of the herbage from perennial ryegrass swards with and without white clover

Abstract

Selected herbage samples from a 6-year experiment in which nitrogen rates between 0 and 897 kg/ha were applied annually on perennial ryegrass swards were analysed for nitrate-nitrogen, true-protein and non-protein nitrogen, water-soluble carbohydrate, potassium and sodium content and for amino acid composition. The nitratenitrogen content of the herbage increased with increasing nitrogen rate from 224 kg/ha upwards, but the potentially toxic level of 220 mg/100 g dry matter was not reached until the annual nitrogen rate was about 560 kg/ha. On average, at the 897 kg nitrogen/ ha rate the non-protein nitrogen content had increased to 27-5 % of the total nitrogen yield, and 40-3 % of the non-protein nitrogen yield consisted of nitrate nitrogen. Nitrate content was shown to be a sensitive indicator of the level of nitrogen nutrition of the herbage, the optimum nitrogen rate for dry-matter production coinciding with a nitrate-nitrogen content of approximately 100 mg/100 g dry matter. The amino acid composition of the herbage varied little with either the rate of nitrogen or the date of cutting. It was demonstrated that, on average, a 1 % unit increase in the crude-protein content of the herbage was accompanied by a 1 % unit decrease in the carbohydrate content. The sodium content of the herbage increased with increasing nitrogen rate up to between 448 and 560 kg/ha, but the potassium content showed little variation. INTRODUCTIONs t a g e o f 8 r o w t h o n e a c h occasion > and t h e yields of herbage dry matter and crude protein were deterThe yield results have been reported (Reid, 1970(Reid, , mined. 1972) for a 6-year experiment designed to obtain Herbage samples were analysed for nitratedetailed information on the response curves relating nitrogen, water-soluble carbohydrate, potassium herbage dry-matter and crude-protein yields to and sodium content from all replicates of nine nitrogen application rate on perennial ryegrass nitrogen treatments (0, 112...897 kg nitrogen/ha) swards with and without white clover. To supple-on both the grass and clover and the pure-grass ment this information selected herbage samples swards at all cuts in the first, third and sixth years, from the experiment were analysed for nitrate-True-protein and non-protein nitrogen analyses nitrogen, true protein and non-protein nitrogen,' were made on samples from all replicates of five water-soluble carbohydrate, potassium and sodium nitrogen treatments (0, 224...897 kg nitrogen/ha) content, and amino acid composition.on the pure-grass sward only at all cuts in the 3 EXPERIMENTAL PROCEDURE y e a r S ' ^nd amino-acid analyses on samples from one replicate of the same five nitrogen treatments The treatments, design and methods were de-on the pure-grass sward at all cuts in the third year scribed in an earlier paper (Reid, 1970). Briefly, a only. series of 21 nitrogen rates ranging from 0 to For the nitrate-nitrogen analysis 1 g of dried 897 kg/ha was applied in five equal dressings each sample was extracted with 80 ml boiling water for yea...

Incidences phytotechniques et zootechniques d'une réduction ou d'une suppression de la fertilisation azotée sur des prairies pâturées par des vaches laitières

“…La teneur en sodium a été significativement plus faible dans le lot 0-N. Cette diminution a été reliée à une plus grande consommation de sel à partir des pierres à lécher dont disposaient les animaux en prairie. L'augmentation des teneurs en sodium dans des prairies composées de trèfle et graminées est rapportée par Reid et Strachan [37].…”

Agromorphological characterization, cyanogenesis and productivity of accessions of white clover (Trifolium repens L.) collected in Northern Spain

“…The ability of white clover to fix nitrogen may increase the nitrogen content of the soil and partly substitute nitrogen fertilization (Frame & Newbould 1986;Allen 2008). In addition, white clover improves the nutritional value of pasture by increasing its protein and mineral contents (Reid & Strachan 1974), and also improves its digestibility and palatability (Jones & Roberts 1991). However, under conventional management, the application of nitrogenous mineral fertilizers may negatively affect clover, and alter the botanical composition of pasture (Garcia et al 2005).…”

Less intensified grazing management with growing fattening bulls

“…In the HN group, the smaller calcium contents were associated with the reduction of white clover when nitrogen fertiliser was increased [24]. The increase in sodium content with an increase in mineral nitrogen fertiliser was reported by Reid and Strachan [45]. On the whole, it appeared that the different managements in the pastures grazed by the growing bulls induced only rather small differences in terms of sward characteristics.…”