Effects of nitrogen fertilizers on total nitrogen, soluble nitrogen and soluble carbohydrate contents of grass

Abstract

Italian rye-grass given ammonium sulphate or sodium nitrate at 56 or 112 lb. N/acre was analysed for total nitrogen, soluble nitrogen (non-protein-nitrogen) and soluble carbohydrates.Ten days after applying fertilizer the differences in total-N between the grass receiving 56 and grass receiving 112 lb. N/acre were very small. Total-N in grass decreased with growth, but the effect of the rate of nitrogen on total-N increased. At first the grass given sodium nitrate contained more soluble nitrogen than grass given ammonium sulphate, the difference being greater at 56 lb. N/acre; soluble nitrogen decreased with increasing growth. Ten days after applying fertilizer, the nitrate-N content of grass was very high (ranging from 0·1 to 0·9% in the D.M.) and it gradually decreased. At both levels of nitrogen application, grass given sodium nitrate contained much more nitrate-N than grass given ammonium sulphate. Forty days after applying nitrogen the nitrate-N contents of grass which received 56 and 112 1b. N/acre as ammonium sulphate were 0·039 and 0·222% of the dry matter, respectively; the grass supplied with sodium nitrate gave values of 0·082 and 0·438%.Total soluble carbohydrates in the grass were small early in growth and gradually increased. Nitrogen dressings had little effect on the content of soluble sugars (glucose + fructose + sucrose) but greatly decreased the fructosan. The pattern of changes in the total soluble carbohydrate content followed that in fructosan content. Early in growth, the total soluble carbohydrate/crude protein ratio was very small in grass from all treatments except the ‘control’. This ratio increased with growth and at the last sampling was 2·13 in grass receiving no nitrogen, and in grass supplied with 56 and 112 lb. N/acre as ammonium sulphate it was 1·44 and 0·72 respectively; the corresponding figures for grass receiving sodium nitrate were 1·13 and 0·66. The total soluble carbohydrate carbon/soluble nitrogen ratio in grass with no nitrogen was 18 at the first sampling and it increased gradually, reaching 70 at the last sampling. This ratio was considerably less with all nitrogen treatments than with ‘control’. The values obtained with 112 lb. N/acre were less than those obtained with 561b./acre, irrespective of the form of nitrogen used.The relationship between the soluble carbohydrate carbon content and the soluble nitrogen in grass is illustrated graphically and discussed.

Soil compaction effects on second‐harvest yields of perennial ryegrass for silage

“…Both the amount and the timing of rainfall were considered in view of their relevance to soil water supply and the transport of applied fertilizer to the root zone. The amount of rainfall during the 14 d after mowing, and the 10 d after fertilizer application, characterized the conditions at commencement of regrowth (usually visible as 'greening-up' of the grass) and peak N concentration in the herbage (Nowakowski, 1962). The time interval after first mowing, and after fertilizer application, until a typical rainfall event of ≥ 2 mm d Ϫ1 (the long-term daily average for June) was chosen to represent the time taken for nutrient levels in the soil to be increased by dissolving and infiltrating into the upper root zone.…”

Chemical composition of pastures in relation to grass tetany in beef breeding cows

“…These include the application of fertilisers, particularly nitrogen, and frequent defoliation (Waite 1957;Alberda 1960;Nowakowski 1962;Davies 1965;Jones, ap Griffith, and Walters 1965). Moreover, leaves are generally lower in carbohydrate than stems (Jones 1962).…”

The Chemical Composition of a Range of Forage Grasses Grown Under Two Nitrogen Fertiliser Inputs and Harvested at Different Stages of Maturity

“…An exception to this trend was for Harvest 4 and 5 where herbage DM concentration did not differ (P > 0.05) between the two N fertiliser treatments. Nowakowski (1962) reported that WSC concentration decreased in grasses with increasing levels of N fertilisation due to an accelerated growth rate following application. The increase in BC and decrease in WSC concentration with N fertiliser addition may have negative implications for grass ensilability.…”