The effect of fertiliser nitrogen on the production of irrigated pasture with and without clover

Abstract

ABSTRACI Yield responses of irrigated pasture to nitrogenous fertiliser were studied on a grass/clover sward and on a grass sward. At rates of application of up to 400 Ib nitrogen/acre/year responses on a grass/ clover sward averaged 5 to 6 Ib dry matter per pound of fertiliser nitrogen in a mowing trial. The amount of fertiliser nitrogen required on a grass sward to equal the yield of a grass/clover sward receiving no fertiliser nitrogen was 450 Ib to 500 Ib under mowing conditions (annual yield 14,000 lb dry matter per acre) and approximately 300 lb under grazing (annual yield 17,000 lb dry matter per acre). Suppression of white clover by high rates of fertiliser nitrogen was much less severe than usually found in experiments in Europe and the U.S.A. At a rate of application of about 800 Ib nitrogen/acre/year on a grass/clover sward, white clover still accounted for 15 percent of the yield, but at an application rate of 250 lb to 300 lb fertiliser nitrogen per acre, white clover apparently ceased to make a positive contribution to the nitrogen supply of associated grasses. Grown as pure swards receiving 360 lb fertiliser nitrogen/acre/ year, cocksfoot (Dactylis glome rata L.) gave a higher summer and annual yield than perennial ryegrass (Lolium perenne L.

Yield and Botanical Composition of an Irrigated Grass‐Legume Pasture as Influenced by Fertilization1

“…The observation that approximately 250 kg Njha were needed for maximum production at the Holt County site is in agreement with conclusions of research reported by Parsons (1958), Lorenz et aL (1'961), and Maas et al (1962)-The requirement of 560 kg Njha for maximum production at the North Platte site is higher than many reported N requirements for maximum production but is in general agreement with the research reported by Weeda (1970), Dotzenko (1961), and Krogman (1970). TheN rates required for maximum forage production may not necessarily correspond to the rates required for maximum economic return which, of course, will be altered by the price of N fertilizer and the value of the forage produced.…”

“…In some studies, N fertilization has increased the grass percentage while decreasing the percentage of legumes in the mixture (Gomm, 1969;Gardner et aL, 1960;Wilson and Dubetz, 1963;Maas et aL, 1962). Weeda (1970), however, found that suppression of white clover (Trifolium repens L) by high N rates was much less than expected. Lorenz et aL (1961) reported an increase in the percentage of alfalfa in a fertilized, irrigated mixture of bromegrass and alfalfa.…”

Effects of rates and times of nitrogen application on the production and composition of dairy pastures in Waikato district, New Zealand

“…Although N application times in the multiple application trials and in the associated grazing trial (Bryant 1983) were similar, responses under mowing were smaller (Table 4). This was probably because of recycling of the applied N under grazing (Weeda 1970; also C. During, reported by Sherlock & O'Conner 1973). The difference was dwarfed, however, by variation in milkfat production responses which ranged from 0 to > 1.4 kg/kg N (Table 4).…”

The efficiency of pastures and forage crops in photosynthetic conversion of solar radiation in the Waikato District, New Zealand

“…(c) Depletion of nutrient supply by rapid growth through spring and early summer. This suggestion is contradicted by evidence that there is little response to heavy applications of nitrogen on irrigated pastures in the Waikato (Weeda 1970). (d) Unsatisfactory grazing intervals.…”