Summer forages under irrigation. 3. The effect of nitrogen fertilizer on the growth, mineral composition and digestibility of a sorghum cross Sudangrass hybrid and Japanese barnyard millet

1985 ◽  
Vol 25 (2) ◽  
pp. 411 ◽  
Author(s):  
DK Muldoon

Sorghum bicolor x S. sudanense hybrid cv. Sudax ST6 and Echinochloa utilis cv. Shirohie were grown under irrigation at Trangie, New South Wales. Six rates of nitrogen (N) fertilizer were applied at sowing: 0, 25, 50, 120, 300, 450 kg N/ha. Height and dry matter yield were recorded at head emergence, together with the leaf hydrocyanic acid (HCN) potential, and leaf and stem dry matter digestibility, nitrogen, sulfur and sodium contents. Both the sorghum hybrid and the millet reached maximum forage yields (16.1 and 7.6 t/ha, respectively) at 350 kg N/ha. However, the tall-growing forage sorghum produced more dry matter than millet and consequently was more responsive to fertilizer nitrogen. In sorghum the leaf HCN potential increased linearly in response to N (8.5 x 10-4 %/kg N.ha). Since there was no compensating increase in the sulfur content (0.072%), and, assuming a requirement of 1.2 g S/g of HCN detoxified, sorghum lacked sufficient sulfur to detoxify the HCN potentially released in the rumen from sorghum receiving 150-200 kg N/ha. At this rate of nitrogen application, sorghum was producing only two-thirds of its forage yield potential. The sodium content of sorghum (0.013%) was not affected by nitrogen. In millet the nitrogen and sodium contents increased as applied nitrogen promoted growth. Plant sulfur was diluted initially but the nitrogen: sulfur ratio increased steadily (0.0067 units/kg N.ha). In contrast to sorghum, therefore, nitrogen fertilizer can be used to increase the dry matter yield of millet without jeopardizing forage quality and hence animal production.


Weed Science ◽  
1996 ◽  
Vol 44 (3) ◽  
pp. 634-639 ◽  
Author(s):  
Deirdre Lemerle ◽  
Birgitte Verbeek ◽  
Neil E. Coombes

The influence of wheat variety on the dose-response of annual ryegrass to diclofop-methyl (POST) was examined in the field in 1992 and 1993 in southern New South Wales, Australia. The aim was to determine if planting a strongly competitive variety of wheat improved control of annual ryegrass at reduced doses of diclofop-methyl. Suppression of ryegrass was dependent on herbicide dose, season, and wheat variety. In the absence of herbicide, dry matter (DM) production of annual ryegrass at 300 plants m−2at anthesis was 500 g ha−1with Dollarbird and Katunga compared to 1000 g ha−1with Rosella or Shrike in 1992. In 1993, DM was approximately 150 g ha−1with Dollarbird or Katunga, and 350 g ha−1with Shrike or Rosella. Ryegrass DM was reduced by diclofop-methyl to a greater extent, relative to the weedy unsprayed controls, with less competitive varieties Rosella and Shrike than with the more competitive Dollarbird or Katunga. Diclofop-methyl at 0.28 kg a.i. ha−1reduced DM of ryegrass growing with Katunga to less than 100 g m−2in 1992, compared to more than 200 g m2with the other varieties. In 1993, diclofop-methyl was more effective on ryegrass, and the same dose reduced ryegrass DM to almost zero in all varieties. Grain yields in unsprayed weedy controls of Dollarbird and Katunga were reduced approximately 20% by annual ryegrass compared with yields achieved with herbicides in both years. Yields of Rosella and Shrike in the unsprayed controls were reduced about 40% in 1992 and 60% in 1993. Only small increases in grain yields of all varieties occurred from diclofop-methyl doses above 0.13 kg a.i. ha−1. Poorly competitive varieties were dependent on herbicides to achieve grain yield potential and had a greater risk of weed survival when herbicide efficacy was reduced. In contrast, strongly competitive varieties, likely to retard build-up of weed seed in the soil, are less dependent on herbicides to achieve grain yield potential, and therefore result in reduced weed control cost.



1991 ◽  
Vol 42 (3) ◽  
pp. 379 ◽  
Author(s):  
MK Conyers ◽  
MK Conyers ◽  
GJ Poile ◽  
GJ Poile ◽  
BR Cullis ◽  
...  

Twenty-three surface soils (0-10 cm) sampled from major New South Wales lime trials were incubated at six lime rates, from 0 to 10 t/ha, and used in pot trials with barley (Hordeurn vulgare cv. Schooner) which was grown for five weeks. Each replicate pot was soil tested for exchangeable cations (Ca, Mg, K, Na, Mn, Al), pH in 0.01 M CaCl2, and Al in the 0.01 M CaCl2 extract by pyrocatechol violet (total Al) and by reaction for 15 s in 8-hydroxyquinoline (monomeric Al). The latter was also converted to the activity of Al3 in the 0.01 M CaCl2 extract. The soil tests were compared for their prediction of the dry matter yield of whole tops of barley. The four tests for aluminium (exchangeable Al as Al/ECEC; total 0.01 M CaCl2 extractable Al; monomeric 0.01 M CaCl2 extractable Al; and Al3+ activity in 0.01 M CaCl2) were each better indicators of the infertility of the acid soils than soil pH. The prediction of the dry matter yield of barley by the four aluminium tests was improved by the inclusion of exchangeable soil manganese in the statistical analysis. The use of 0.01 M CaCl2 is recommended as a routine extraction procedure for diagnosing Al toxicity. Soil Mn should also be measured and included in correlations with barley growth. Pyrocatechol violet is the recommended analytical procedure for Al owing to its comparative simplicity.



1978 ◽  
Vol 18 (94) ◽  
pp. 718 ◽  
Author(s):  
DL Garden ◽  
DR Brooks ◽  
J Bradley

The effects of superphosphate rate (nil; 250 kg ha-l initial with 125 kg ha-1 maintenance; and 500 kg ha-1 initial with 250 kg ha-1 maintenance) and cutting interval (2, 4, 6 or 8 weeks) on dry matter yield, growth rate, botanical composition and chemical composition of native pastures on a sandstone soil in the Clarence Valley, New South Wales were studied over a period of three years. Mean annual dry matter yield of unfertilized native pasture was 990 kg ha-l and this was increased to 1322 kg ha-1 at the higher rate of superphosphate. Dry matter yield was depressed from 1587 to 647 kg ha-1 by decreasing cutting interval from 8 weeks to 2 weeks. Pasture growth was limited to the September to May period and 87 per cent of the total annual production occurred in summer and autumn. Maximum growth occurred in the February/March period, with 16.2 kg ha-1 day-1 being the maximum recorded for the unfertilized pasture and 19.9 kg ha-1 day-1 for pasture at the higher rate of superphosphate. Changes in botanical composition were neither large nor consistent. Phosphorus content of the native pasture averaged 0.12 per cent. Crude protein content averaged 7.4 per cent, with levels in standing herbage in winter-spring falling to 3 per cent. Phosphorus yield was 1.1 kg ha-1 year-1 and crude protein yield was 65.8 kg ha-1 year-1. Superphosphate increased phosphorus content and yield, and crude protein yield. Increasing cutting interval decreased phosphorus and crude protein contents but increased phosphorus and crude protein yields by its effect on dry matter yield. Maximum yields obtained were 3.3 kg ha-1 year-1 phosphorus and 100 kg ha-1 year-1 crude protein. It was concluded that the increases obtained would be insufficient to produce worthwhile improvements in animal production, and that an increase in the legume content of these pastures is required before this could occur.



1966 ◽  
Vol 6 (23) ◽  
pp. 388 ◽  
Author(s):  
RL Colman

A factorial field experiment, comparing three rates of nitrogen as anhydrous ammonia, two seeding rates of oats, and the presence or absence of a herbicide applied to grass pastures before sod-seeding, was conducted at Kyogle, New South Wales in 1964. Plots were sown in mid-autumn and harvested in winter and early spring. Increased applications of nitrogen and the higher seeding rate increased both dry matter yield and total nitrogen content. Application of herbicide significantly increased yield at the low rates of nitrogen but not at the highest rate. Anhydrous ammonia at 120 lb of nitrogen an acre had no effect on the germination of oats seed and provided adequate nitrogen for growth of oats without the need for herbicide application or cultivation of the grass pasture. The results suggest that oats can be successfully sod-seeded into grass dominant pastures by using 120 lb of nitrogen as anhydrous ammonia and four bushels of oats an acre.



1994 ◽  
Vol 34 (6) ◽  
pp. 753 ◽  
Author(s):  
GM Lodge ◽  
MG McMillan ◽  
AJ Schipp ◽  
AS Cook

Two experiments were conducted at Tamworth, New South Wales, to assess the effects of herbicides applied post-sowing pre-emergence, and at 2 post-emergence growth stages, on Danthonia (wallaby grass) dry matter yield, plant number, and plant phytotoxicity. Phytotoxicity was scored visually on a 0-5 scale (0, no phytotoxicity; 5, 100% phytotoxicity). In the post-sowing pre-emergence study, no Danthonia plants survived on plots sprayed with metribuzin (375 g a.i./ha), chlorsulfuron (45 g a.i./ha), or simazine (750 and 1500 g a.i./ha). Phytotoxicity was also high at lower rates of metribuzin (187.5 g a.i./ha) and chlorsulfuron (22.5 g a.i./ha). Dry matter yields and plant numbers on 2,4-D amine and ester treatments were not significantly different from those of unsprayed controls. On metsulfuron-methyl (3 and 6 g a.i./ha) and triasulfuron (21.4 g a.i./ha) treatments, plant numbers were similar to the controls, but Danthonia yields were lower (P<0.05). In seedling stands, the only herbicide that reduced (P<0.05) Danthonia dry matter yield compared with the unsprayed control plots was metsulfuron-methyl applied at 6, 12, and 18 g a.i./ha at the 2-4 tiller stage, and at 12 and 18 g a.i./ha at early stem elongation. At both times of application, Danthonia plant numbers were lowest (P<0.05) on the metsulfuron-methyl 12 and 18 g a.i./ha treatments. Phytotoxicity scores were >2 and highest (P<0.05) on all metsulfuron-methyl plots. These studies indicated that a range of chemicals could be used to control broadleaf weed seedlings, without damaging Danthonia seedlings.



1980 ◽  
Vol 20 (104) ◽  
pp. 330 ◽  
Author(s):  
JL Wheeler ◽  
DA Hedges ◽  
KA Archer ◽  
BA Hamilton

An experiment to determine the effect of nitrogen, sulphur and phosphorus fertilizer, applied at sowing, on the growth and chemical composition of a hybrid sorghum x sudangrass forage, is reported. The factorial design was repeated at six sites in northern New South Wales in one year, 1976-77. Urea (50 kg nitrogen ha-1) substantially reduced plant populations at three sites. At the first harvest, dry matter production, after adjustment for plant population, was more than doubled by 20 kg phosphorus ha-1; yields were depressed by nitrogen where phosphorus was withheld. Hydrocyanic acid (HCN) potential (mean 0.04%), was increased 28% by nitrogen fertilizer, and reduced 34% by phosphorus fertilizer. Sulphur content was increased from 0.15 to 0.17% by nitrogen fertilizer, and reduced from 0.175 to 0.142% by the phosphorus treatment; it was unaffected by 20 or 50 kg sulphur ha-1 applied at sowing. At two sites, phosphorus increased the sodium concentration but the enhanced levels were still below recommended dietary requirements. The ratio of nitrogen : sulphur (after adjustment for potential loss of sulphur in the detoxication of HCN), was increased from 25:1 to 29:1 by nitrogen fertilizer. The response to sulphur was slight, and the effect of phosphorus was inconsistent. Similar but reduced effects on growth and composition occurred in the second harvest. Hydrocyanic acid levels were much higher, and the adjusted nitrogen:sulphur ratios were exceptionally wide. On the evidence available it appears that the direct supplementation of animals is the most feasible means of ensuring adequate levels of sulphur and sodium in the diet.



HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1117c-1117
Author(s):  
Paige Hanning ◽  
Dyremple B. Marsh ◽  
Helen Swartz

The use of cowpea as a forage for Central Missouri has been limited. High mid summer temperatures and frequent drought suggest that an alternative forage for livestock may be advantageous during the hot summer months. The ability of cowpea to withstand drought, high temperature and maintain high foliage protein, justifies research of the forage potential of this crop. Forage yield potential of two cowpea cultivars was evaluated in field experiments in 1968 and 1989, For both years a split plot experimental design was utilized with cowpea cultivar the main plot and harvest date the subplot Dry matter yields for both cultivars were similar at the early harvest dates. However, both fresh and dry shoot yields of Vita 3 (V3) were significantly higher than that of California Blackeye #5 (CB #5) at the later harvest stages. CB #5 plants produced a significantly higher stem dry weight while V3 produced higher leaf dry matter. Foliage regrowth after clipping was substantial for both cowpea cultivars. However, V3 produced 30% higher growth than CB #5. In vitro dry matter digestibility (IVDDM) varied with sample date (plant age) and plant parts sampled. IVDDM was 77% for leaves and 60% for stems of CB#5, and 80% for leaves and 65% for stems of V3.



1974 ◽  
Vol 14 (69) ◽  
pp. 526 ◽  
Author(s):  
HJ Fisher

Three rates of nitrogen fertilizer and a standard superphosphate dressing were applied to a Themeda australis grassland with and without broadcast seed of Dactylis glomerata. Two cutting frequencies were imposed and dry matter yields and botanical composition were measured. T. australis responded to nitrogen, but the response was not sufficient for it to predominate over other species, particularly Poa labillardieri, as it had done under low fertility conditions. P. labillardieri yields increased markedly with increasing nitrogen rate. D. glomerata, which established only where nitrogen fertilizer was applied, substantially reduced the increase in P. labillardieri at the high level of nitrogen. Cutting frequency affected botanical composition in degree but not in kind. Both P. labillardieri and D. glomerata yielded less, but T. australis yielded more under more frequent cutting. For pasture improvement in wetter parts of the southern tablelands of New South Wales, it is important to establish a perennial grass at the beginning of the programme to reduce the growth of the undesirable tussock. P. labillardieri.



1994 ◽  
Vol 34 (6) ◽  
pp. 759 ◽  
Author(s):  
GM Lodge ◽  
MG McMillan

Three experiments were conducted at Tamworth, New South Wales, in 1990-92 to assess the effects of a range of broadleaf and grass herbicides, 6 rates of glyphosate and paraquat + diquat, and 4 rates of 2,4-D amine and diuron on the phytotoxicity, dry matter yield, inflorescence number, and seed yield of established Danthonia (wallaby grass) plants. Phytotoxicity was scored visually on a 0-5 scale (0, no phytotoxicity; 5, 100%). Danthonia dry matter yields were not affected (P<0.05) by any herbicide tested, except glyphosate applied at 2360 g a.i./ha. Phytotoxicity was highest for the glyphosate treatment (1440 g a.i./ha) in that study. All rates of glyphosate, and paraquat + diquat rates >250 + 150 g a.i./ha reduced (P<0.05) inflorescence number compared with the unsprayed control. Paraquat + diquat had no significant effect on seed yield, but glyphosate rates >360 g a.i./ha reduced (P<0.05) seed yield compared with the control. In 1992, no damage was observed on 2,4-D amine treatments and phytotoxicity scores were low (<2) for all diuron treatments. Danthonia inflorescence numbers and seed yields were higher (P<0.05) on plots mown in early spring than on unmown treatments. The lack of effect of herbicides such as diclofopmethyl, simazine, fenoxaprop-ethyl, and diuron on Danthonia dry matter yield, and the low phytotoxicity, indicated that a range of chemicals may be used on established Danthonia swards to control perennial and annual grass weeds. Seed yield was more affected than dry matter yield by herbicide, and paraquat + diquat should be used in preference to glyphosate on seed crops.



1986 ◽  
Vol 26 (2) ◽  
pp. 165 ◽  
Author(s):  
GM Lodge

Three irrigated lucerne cultivars, Pioneer Brand 545 (winter dormant), Condura 73 Brand (semiwinter dormant), and CUF 101 (highly winter active), were harvested at fixed cutting intervals of either 25, 28 ,35, 42 or 48 days from September to April in each of four years. This paper reports the effects of these cutting frequencies on the dry matter yield, leaf to stem ratio and persistence of these cultivars. The effect of cutting frequency on mean total yield (the sum of the mean yields for each harvest) was significant (P<0.05) in each year of the experiment, except year 3. Yields were highest in the 35-day cutting frequency in years 1 and 2. In the fourth year of the experiment the mean total yield of Pioneer Brand 545 and Condura 73 Brand was 29% higher (P<0.05) than CUF 101. By the fourth year substantial amounts of grass were present in the 25- and 28-day cutting interval plots. The contrasts between dormant and active cultivars for the dry matter yield of each of the individual harvests were not consistent in the first two years. In the third and fourth years the active initially outyielded the dormant cultivars at all cutting intervals, but yields of both were generally similar at the end of the season. Increasing the interval between successive harvests generally decreased the mean leaf to stem ratio. The ratio of leaf to stem for CUF 101 was significantly lower (P<0.05) than that for Pioneer Brand 545, with Condura 73 Brand tending to be intermediate. Within cutting intervals, mean declines in plant persistence were similar for cultivars from the different dormancy groups. Largest changes in plant frequency occurred in the fourth year when the mean frequency for the 25- and 28-day plots decreased from 69 to 12% compared with a mean decline from 74 to 65% for the 42- and 48-day cutting intervals. Productive stand life in this experiment was 3 years, even though disease was negligible. Under these conditions grass invasion was mainly related to harvest interval and much less to cultivar dormancy.



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