Greater Dry Matter Yield Research Articles

Effectiveness of elemental S fertilizers on forage grass

Two field experiments were conducted from 1993 to 1995 to compare the effectiveness of various cumulative elemental S and sulphate-S fertilizer applications in increasing dry matter yield (DMY) and S uptake of forage grass. In exp. 1, one sulphate-S (Na2SO4) and two elemental S (Agric-Grade 0-0-0-95 and Tiger 90) fertilizers were applied annually to grass in mid to late April at 10, 20, 30, 40 and 50 kg S ha−1 rates. The increase in DMY from S application was significantly lower with elemental S fertilizers than with Na2SO4 in the first and second years, but in the third year elemental S fertilizers had DMY increase similar to Na2SO4 In exp. 2, a number of elemental S and sulphate-S fertilizers were applied annually to grass in mid- to late April at 15 kg S ha−1 rate. There was a marked increase in DMY from S application in all the 3 yr with the three sulphate-containing S fertilizers (Na2SO4, K2SO4 and CaSO4). When elemental S fertilizers were used, only Turf-Grade 0-0-0-95 increased DMY in all the 3 yr and it produced DMY increase similar to the sulphate-S fertilizers in the third year. Elemental S Prills did not produce any significant increase in DMY in any of the 3 yr. Other elemental S fertilizers [e.g., Elemental S Powder, Agric-Grade 0-0-0-95 and Tiger 90] increased DMY in the third year only, but this increase was still less than the sulfate-S fertilizers. Turf-Grade 0-0-0-95 (with smaller granules) produced greater DMY increase than Agric-Grade 0-0-0-95 (with larger granules) in all the 3 yr (though significant in the third year only). The S fertilizers that contained small amounts of sulphate-S in addition to elemental S were generally more effective in increasing DMY than the similar fertilizers containing only elemental S. The increase in S uptake from applied S in grass showed usually similar trends as DMY increase. In conclusion, the results suggest that some elemental S fertilizers can be as effective in increasing forage DMY on perennial grass as sulfate-S fertilizers. However, depending upon soil type and climatic conditions two or more growing seasons may be needed for S in the elemental S fertilizers to become fully available to the plants. Key words: Elemental S fertilizers, forage yield, grassland, sulphate-S fertilizers, sulphur uptake

Growth and distribution of maize roots under nitrogen fertilization in plinthite soil

To improve efficiency of soil N and water use in the savanna, maize ( Zea mays L.) cultivars with improved root systems are required. Two rainfed field experiments were conducted in Samaru, Nigeria in the 1993 and 1994 growing seasons with five maize cultivars under various rates of nitrogen fertilizer. The capacity of maize for rapid early root growth and to later develop a deep, dense root system was assessed. In addition, the effect of N fertilization on root growth of maize was studied in 1994. The widely cultivated cultivar TZB-SR had a poor root system in the surface soil layer and was more susceptible to early-season drought, as indicated by low plant vigor and aboveground dry matter yield during that time. It had a lower grain yield and a relatively small harvest index, but ranked among the highest in total aboveground dry matter production compared to other cultivars. The size of root system alone did not always relate well with grain yield among cultivars. Partitioning of dry matter within the plant was important in determining differences in grain yield and N stress tolerance between cultivars. A semiprolific cultivar (SPL) had high seedling vigour and a dense root system in the surface soil layer that conferred a greater tolerance to early-season drought stress and improved uptake of the early-season N flush, as indicated by a greater dry matter yield at 35 days after sowing (DAS). It also had a fine, deep, dense root system at flowering that could have improved water- and N-use efficiency in the subsoil (> 45 cm), thereby avoiding midseason drought stress in 1994. SPL had a large harvest index and the greatest yield among cultivars in 1994. Averaged across cultivars, greater root growth and distribution was observed at a moderate N rate of 0.56 g plant −1 than at zero-N or high N (2.26 g plant −1). Differences in root morphology could be valuable as selection criteria for N-efficient and drought-tolerant maize.

Meadow bromegrass response to coated and conventional urea fertilizers

In central Alberta, surface-broadcast urea is usually less effective in increasing grass forage yield than ammonium nitrate (AN) due to volatilization loss. A 2-yr field experiment was conducted in 1994 and 1995 on meadow bromegrass (Bromus bibersteinii Roem and Shult 'Regar') at Eckville, Alberta to compare a number of synthetic con-trolled-release urea fertilizers with conventional urea and AN fertilizers for their effect on dry matter yield (DMY), protein yield (PY), N-use efficiency (NUE) and percent N recovery (NR). The N fertilizers were applied at 100 kg N ha−1 in early June of 1994 and mid-April of 1995. The meadow bromegrass was harvested three times during the May to September growing season. In both years there was a significant forage yield response to applied N. In 1994, the DMY, PY, NUE and NR were similar for urea and AN, and most of the treated urea products were inferior to urea alone. This was most likely due to delayed application of N fertilizer until just before the start of summer rains. In 1995, urea had lower DMY (by 874 kg ha−1), PY (by 177 kg ha−1), NUE (by 8.8 kg DM kg−1 N ha−1) and NR (by 27.3%) than AN. Some of the coated urea products (e.g., Sh. 19, Sh. G) gave significantly greater DMY, PY, NUE and NR than urea alone, though still less than AN. These results suggest that under conditions when surface-applied urea is inferior to AN, its effectiveness can be improved by using Sh. 19 and Sh. G controlled-release urea fertilizers on grassland. The controlled-release fertilizers may be more expensive and therefore, additional cost must be considered as compared with AN before using on a commercial basis. Key words: Ammonium nitrate, bromegrass, controlled-release N fertilizers, forage yield, N recovery, urea

Heterosis and inbreeding depression in forage rape (Brassica napus L.)

Heterosis and inbreeding depression for total fresh and dry weights were studied over two seasons in 15 crosses of six cultivars of forage rape (Brassica napus L.). Some of the hybrids exhibited considerable heterosis over both mid-parent and better parent; followed by depression in the F2. The cross Windal × Canard had 62% and 25% greater dry matter yield over the best cultivar used in this experiment in 1978 and 1979, respectively. Possibilities of the utilization of this hybrid superiority are discussed.

The influence of organic fertilizers, obtained from poplar barks, on the correction of iron chlorosis ofLupinus albus L.

The influence exerted by organic matter on the correction of iron chlorosis inLupinus albus L., grown in calcareous soil, was studied through a pot experiment by incorporating two rates (1.5 per cent and 3 per cent on the soil) of three organic fertilizers obtained from poplar barks. The fertilizers differed in the length of humification process and in the integration with different materials,i.e.: H fertilizer: 8 months humified poplar barks without any addition, HF fertilizer: 4 years humified poplar barks with 4 per cent of metallic iron, HP fertilizer: 18 months humified poplar barks with 25 per cent of poultry manure. The higher rate (3 per cent) of the H fertilizer was the most efficient in reducing chlorosis symptoms and gave the greatest dry matter yield. Among the treatments with the lower rate (1.5 per cent), the HF fertilizer gave the best results; conversely, the HP fertilizer failed to correct chlorosis and to enhance yield. Therefore the experiment suggested that organic fertilizers are useful to correct iron chlorosis, provided their phosphorus content is low and they have undergone a prolonged humification process; furthermore, integration with small amounts of iron leads to a considerable saving of organic fertilizer.

Influence of Varied Phosphorus Supply on Growth and Xylem Sap Cytokinin Level of Sycamore (Platanus occidentalis L.) Seedlings

Effects of varying levels of phosphorus (P) on sycamore (Platanus occidentalis L.) growth and on the endogenous cytokinin levels in the xylem sap were tested. The seedlings were grown in aerated nutrient solutions in the greenhouse. Photoperiod was held constant at 16 hours. Four P concentrations, 0.02, 0.10, 0.50, and 2 mm, were used. There were no P deficiency symptoms even at the lowest P concentration. The maximum growth occurred in seedlings grown in 0.10 mm P. The greatest dry matter yield as well as stem height, stem diameter, and leaf area were produced at 0.10 or 0.50 mm P. The amount of cytokinin in xylem sap for each harvest during P nutrition followed closely the dry matter values, stem height, stem diameter, and leaf area.

Emergence, seedling development and survival of native and exotic grasses on a sandy red earth in South-Western Queensland.

The growth and development of eight perennial grasses, from sowing until flowering, was studied in the field on a sandy red earth near Charleville, south-western Queensland. They included four species native to this soil, Thyridolepis mitchelliuna, Aristida armata, Digitaria ammophila and Monachather paradoxa, and four exotic species Cenchrus ciliuris cv. Biloela, Anthephora pubescens, Eragrostis curvula and Schmidtia bulbosa. Cenchrus ciliaris, A. pubescens and S. bulbosa emerged much more promptly than the other species and much less viable seed was left in the soil after the fist germination event. The native species tillered and flowered earlier than the exotic grasses and survived better under adverse growing conditions. Average survival at the end of the first growing season, during which good seasonal conditions pre- vailed, was 30% of the emergent seedlings. Schmidtia bulbosa performed best within the exotic group and this was associated with early tillering and earlier flowering. The exotic species needed at least a four month growing season before they flowered under field conditions compared with two months or less for the native grasses. However this disadvantage was offset somewhat by their greater dry matter yield at this stage of development.

Aqueous ammonia compared with other nitrogenous fertilizers as solids and solutions on grass

SUMMARYField experiments with Italian ryegrass cut four times a year compared aqueous ammonia with ammonium sulphate and with a mixture of ammonium nitrate and urea (equal parts by weight). In 1963 four rates of nitrogen, 224, 448, 672 and 896 lb/acre, were applied as single and split dressings of injected aqueous ammonia, as solid ammonium sulphate and as injected solution of ammonium sulphate. There was little difference in total dry-matter yield between a single injection of aqueous ammonia and the split dressing of solid. Injecting ammonium sulphate solution eliminated scorch caused by single applications of solid supplying 448 lb N/acre or more and gave significantly greater dry-matter yields. A single application of 448 lb N/acre provided enough nitrogen to sustain the response of the grass to the end of the season.In 1964 a single injection of aqueous ammonia was compared with ammonium nitrate/urea applied as solid or solution at 280, 560 and 840 lb N/acre. There was no difference in total dry-matter yield between aqueous ammonia and ammonium nitrate/urea at rates of 560 and 840 lb/acre. At 280 lb/acre a split dressing of solid produced most dry matter. More than 280 lb N/acre was required, therefore, as a single application in spring to last the whole season, but this rate of nitrogen applied as a split dressing was almost sufficient to give maximum yield.In both experiments the seasonal distribution of dry matter was similar for single and split applications except in 1963 when large single injections of ammonium sulphate produced greater yields at the third cut than the split applications. The percentage of nitrogen recovered in the harvested grass decreased as nitrogen rate was increased and was greater from single than split applications. Recovery of nitrogen from aqueous ammonia was less efficient from four injections than one, and was greater in 1964 than 1963 due to better penetration of the sward by injector tines. Least nitrogen was recovered from surface-applied solutions of ammonium nitrate/urea. Regressions of dry-matter yield on nitrogen yield showed that single injections of aqueous ammonia were as efficient as other fertilizers tested.

The effect of frequency and time of cutting on the production and quality of a barley grass (Hordeum leporinum) dominant pasture

A grazing experiment on a barley grass (Hordeum leporium Link) dominant pasture at Deniliquin, New South Wales, was carried out from May to November 1964. Monthly grazing of this pasture resulted in a greater dry matter yield of both green and total barley grass, and of crude protein, than when grazing occurred less frequently. The greatest stimulus to production was achieved when grazing occurred in August or September when the plants were approaching flowering. Rat's-tail fescue (Vulpia myuros (L.) K.C. Gmel), the other main component of the pasture, was not stimulated to greater total dry matter production by increasing the frequency of grazing. However, significantly more green fescue was harvested from areas grazed most frequently. The quality of both species, as estimated by nitrogen content and in vitro digestibility of barley grass and nitrogen content of fescue, was higher late in the season on the monthly grazed areas than on areas grazed less frequently.