Some effect of sodium application on the yield and chemical composition of pasture grown under differing conditions of potassium and moisture supply

Abstract

The effects of Na fertiliser (supplied as an NPK-Na compound) on herbage yield and composition were examined at two different sites to see if pasture responses to Na were affected by differences in K and moisture availability. At one site, pasture was grown under conditions of moisture stress and limited K availability, whereas at the other site the pasture was grown under comparatively non-stress conditions.The results were interesting in that Na fertilisation appeared to be detrimental to pasture yield and quality under conditions of moisture stress and suboptimal K supply, whereas under the non-stress conditions it actually increased herbage N offtake, marginally improved the nutritional quality of the pasture and produced appreciable (albeit non-significant) increases in DM yield. It was suggested that an important effect of Na on grass production may have been its ability to enhance the rate of NO 3 uptake by plants, thereby minimising NO 3-N losses from the soil-plant system by denitrification. However, because the amount of N fertiliser used in the experiments (i.e. 390 kg N ha -t y r -l ) was close to that normally required for maximum yield production (N max) under Northern Ireland conditions, the scope for yield increases in response to Na-elicited improvements in N offtake were thought to have been very limited at both experimental sites.On the basis of results from both the present study and previous field trials, a unifying theory is presented to explain the differential effects of Na on NO 3 uptake and herbage growth under different sets of circumstances.

Diagnosis and Recommendation Integrated System Norms for Jackfruit (Artocarpus heterophyllus Lam.) Nutrient Status Evaluation

“…For example, K uptake and efficiency from either soil or K applications often depended on the rate of N used (Ebelhar, Kamprath, & Moll, 1987). Likewise, K was known to have a key role in N uptake and translocation (Cushnahan, Bailey, & Gordon, 1995). Therefore, some nutrients (such as N and K) need to be kept in the specific nutrient ratios to develop the plants.…”

A preliminary diagnosis and recommendation integrated system (DRIS) model for diagnosing the nutrient status of sweet potato (Ipomoea batatas)

“…Nitrogen and S are vital constituents of sulphur-containing amino acids and need to be present in quite specific proportions if the requisite proteins and proteincontaining structures are to be synthesized by plants (Marschner 1995). Equally, K is known to have a key role in N uptake and translocation (Minotti et al 1968;Cushnahan et al 1995), and therefore both N and K need to be present in quite specific proportions if N accumulation and subsequent assimilation into proteins is to take place at optimal rates. There is perhaps less obvious physiological rationale for maintaining specific P/N, K/P, S/P and K/S ratios in leaf tissue, and this is probably why at least three of these ratios (P/N, K/P and K/S) had CV's greater than 30%.…”

Nitrogen-sodium concentrated complex fertilisers (CCF’s)versus nitrogen-sodium blends: Effects on ammonium and nitrate uptake by perennial ryegrass plants replete with potassium

“…Numerous studies have indicated that in situations where K is moderately deficient, plant uptake of N, and shoot dry matter (DM) yield, may be enhanced by the application of Na containing fertilisers (Bailey, 1993;Phillips, 1991, 1993a;Cushnahan and Bailey, 1994;McNaught and Karlovsky, 1964;Smith et al, 1980), whereas in situations of K abundance, Na K + would have been made available to drive the NO − 3 transport mechanism, and hence NO − 3 would either have accumulated in roots hindering further N uptake by feed back regulation (Haynes, 1986), or else would be reduced in root tissue at exorbitantly high C costs (i.e., 2.17 moles of C per mole of NO − 3 reduced) and thus at the expense of subsequent NO − 3 uptake (Cushnahan et al, 1995;Raven, 1985). In contrast, in K sufficient situations, they found that the application of Na had little or no effect on DM production or N recovery by grassland swards (Bailey, 1993;Bailey and Cushnahan, 1994).…”

“…in concentrated complex fertiliser (CCF) form. Cushnahan et al (1995) proposed a physiological framework to explain the differential effects of Nacontaining CCF's on NO − 3 uptake under K-deficient and K-sufficient conditions. Based on the results of previous studies they suggested that the initial rate of NO − 3 absorption by plant roots is directly proportional to the supply of metallic cations (K + , Na + , Mg 2+ , Ca 2+ ) in the soil solution (Minotti et al, 1968(Minotti et al, , 1969.…”

“…The afore-mentioned authors conducted field experiments on two contrasting sites to investigate the effects of Na application on ryegrass production under K-deficient and K-replete conditions (Cushnahan et al, 1995). Contrary to their expectations, the results showed that in the K-deficient situation, Na application had either no effect on crop production or else was detrimental to plant growth and N uptake, whereas in the K-replete situation, it was actually beneficial to herbage production and N recovery by swards.…”