SEASONAL PATTERNS OF NITROGEN FIXATION AND DRY MATTER PRODUCTION BY CLOVERS GROWN IN THE PEACE RIVER REGION

1980 ◽  
Vol 60 (3) ◽  
pp. 847-858 ◽  
Author(s):  
W. A. RICE

Alsike clover (Trifolium hybridum L.) and red clover (T. pratense L.) were established in field plots on an Orthic Gray Luvisol (Hazelmere CL) and a Black Solod (Landry CL) in 3 consecutive yr, 1972, 1973 and 1974. Data were collected in the 2 yr following the year of establishment. The factors measured included seed and forage yield, dry matter production rate, potential nitrogenase activity (acetylene reduction), soil temperature, air temperature, soil moisture and NH+4-N and NO−3-N content of the soil. Based on calculations using the theoretical C2H2:N2 ratio of 3:1, alsike clover annually fixed 20.8–143.0 kg N/ha, and red clover fixed 15.3–77.3 kg N/ha on the Orthic Gray Luvisol. Also, alsike clover fixed more N2 earlier in the growing season than red clover. The estimate of annual N2(C2H2) fixation by both clovers on the Black Solod was less than one half that on the Orthic Gray Luvisol. There was little difference between the N2(C2H2) fixation by clover crops harvested for forage and those used for seed production. However, the amount of N2(C2H2) fixed always equalled or exceeded the amount of nitrogen removed in the seed, but only occasionally exceeded the amount removed in the forage. Yield and N2(C2H2) fixation varied widely among years, suggesting considerable climatic influence. However, the measured climatic and soil factors were not consistently correlated with potential nitrogenase activity. The seasonal pattern of potential nitrogenase activity appeared to be influenced by the phenological development of the plant. Activity commenced early in May, increased to a maximum about mid-June (flower initiation), and then decreased and generally remained low for the remainder of the growing season. Significant deviations from the usual seasonal profile of potential nitrogenase activity occurred in years with periods of moisture stress or with above average precipitation and soil heat units.

2010 ◽  
Vol 61 (5) ◽  
pp. 353 ◽  
Author(s):  
L. L. Burkitt ◽  
D. J. Donaghy ◽  
P. J. Smethurst

Pasture is the cheapest source of feed for dairy cows, therefore, dairy pastures in Australia are intensively managed to maximise milk production and profits. Although soil testing commonly suggests that soils used for dairy pasture production have adequate supplies of phosphorus (P), many Australian dairy farmers still apply fertiliser P, often by applying smaller rates more frequently throughout the year. This study was designed to test the hypotheses that more frequent, but lower rates of P fertiliser applied strategically throughout the growing season have no effect on dry matter production and P concentration in perennial ryegrass (Lolium perenne L.), when soil extractable P concentrations are above the critical value reported in the literature. Three field sites were established on rain-fed dairy pasture soils ranging in P sorption capacity and with adequate soil P concentrations for maximising pasture production. Results showed that applied P fertiliser had no effect on pasture production across the 3 sites (P > 0.05), regardless of rate or the season in which the P was applied, confirming that no P fertiliser is required when soil extractable P concentrations are adequate. This finding challenges the viability of the current industry practice. In addition, applying P fertiliser as a single annual application in summer did not compromise pasture production at any of the 3 sites (P > 0.05), which supports the current environmental recommendations of applying P during drier conditions, when the risk of surface P runoff is generally lower. The current results also demonstrate that the short-term cessation of P fertiliser application may be a viable management option, as a minimal reduction in pasture production was measured over the experimental period.


1995 ◽  
Vol 46 (7) ◽  
pp. 1401 ◽  
Author(s):  
RR Gault ◽  
MB Peoples ◽  
GL Turner ◽  
DM Lilley ◽  
J Brockwell ◽  
...  

Nodulation, N2 fixation (estimated by 15N natural abundance methods) and dry matter production were studied in a lucerne (Medicago sativa) crop managed for hay production at Ginninderra Experiment Station, A.C .T. Measurements were taken in the year of establishment and during two subsequent growing seasons. There were three treatments: (1) no inoculation and no annual fertilizer applied, (2) initial inoculation and superphosphate applied annually, (3) no inoculation, superphosphate applied annually and ammonium sulfate periodically. Before planting and after each growth season, soil was analysed for extractable mineral nitrogen, total nitrogen and the 15N natural abundance of this nitrogen, to the depth explored by lucerne roots. Before planting, no appropriate root-nodule bacteria (Rhizobium meliloti) were detected in the soil and initially plants were nodulated only in the inoculated treatment. Thereafter nodulation increased on the other treatments. Eight months after sowing there were no differences between treatments in numbers of R. meliloti g-l soil or in nodulation. In the third growing season, almost 30 kg ha-1 (dry wt) of nodules were recovered to a depth of 25 cm. These nodules were primarily located on fine, ephemeral roots and many appeared to be renewed after cutting of the lucerne. In the year of establishment, dry matter yields (0% moisture) totalled 3 to 4 t ha-1 in three hay cuts. In succeeding years, total yields were in the range 10 to 13 t ha-1 in four or five cuts per season. Nitrogen removed in the harvested lucerne reached 340 to 410 kg N ha-lyr-l in the second and third years and between 65 and 96% of this N arose from N2 fixation, depending on the method of calculation used. Poorer dry matter production and N2 fixation in treatment 1 in the third growing season was attributed to an insufficient supply of available phosphorus. Fixed N removed in Lucerne hay from treatment 2 totalled at least 640 kg N ha-1 in the three years of the experiment. Also, there were substantial increases in soil nitrogen due to lucerne growth. Although soil compaction made the quantification difficult, at the end of the experiment it was estimated that there was at least an extra 800 kg N ha-1 in the total soil nitrogen under lucerne compared to strips of Phalaris aquatica grown between the lucerne plots. It was concluded that lucerne contributed at least the same amount of fixed nitrogen to the soil as was being removed in the harvested hay.


Author(s):  
R.B. Allen ◽  
I.R. Mcdonald ◽  
N.A. Cullen

White clover (Trifolium repens), red clover (T. pratense), subtcrrnnean clover (T. subterraneum) and alsike clover (T. hybridum) were sown singly or in combinations at three sites in Otago. Ryegrass (Lolium perenne) was included in all clover treatments and was also sown alone. Lucerne (Medicago sativa) was sown alone at two sites. Herbage dry matter production was measured over a three-year period. At the high fertility lnvermay site, white and red clovers gave similar total and legume dry matter production and were markedly superior to alsike and subterranean clovers. White and nlsike clovers were most productive at the higher altitude, low fertility Berwick site, and at the dry, medium fertility Dunback site red clover produced the highest yields. Lucerne greatly outyielded all other species in the second and third years at Invermay and in the third year at Dunback.


2014 ◽  
Vol 65 (11) ◽  
pp. 1147 ◽  
Author(s):  
Philip J. Larkin ◽  
Matthew T. Newell ◽  
Richard C. Hayes ◽  
Jesmin Aktar ◽  
Mark R. Norton ◽  
...  

Dual-purpose cereals have been important for increasing the flexibility and profitability of mixed farming enterprises in southern Australia, providing winter feed when pasture dry matter production is low, and then recovering to produce grain. A perennial dual-purpose cereal could confer additional economic and environmental benefits. We establish that, at the end of a second growth season, selected perennial cereals were able to achieve up to 10-fold greater below-ground biomass than a resown annual wheat. We review and expand the data on available, diverse, perennial, wheat-derived germplasm, confirming that perenniality is achievable but that further improvements are essential through targeted breeding. Although not yet commercially deployable, the grain yields and dry matter production of the best performing lines approach the benchmarks predicted to achieve profitability. On reviewing the genomic composition of the most promising wheat-derived perennials, we conclude that the best near-term prospect of a productive breeding program for a perennial, wheat-derived cereal will utilise a diploid, perennial donor species, and the most promising one thus far is Thinopyrum elongatum. Furthermore, the breeding should be aimed at complete wheat–Th. elongatum amphiploids, a hybrid synthetic crop analogous to triticale. We advocate the generation of many primary amphiploids involving a diversity of Th. elongatum accessions and a diversity of adapted annual wheat cultivars. Primary perennial amphiploids would be inter-crossed and advanced with heavy, early-generation selection for traits such as semi-dwarf plant height, non-shattering heads, large seed size and good self-fertility, followed by later generation selection for robust perenniality, days to flowering, grain yield, forage yield, stability of grain yield across seasons, and disease resistance.


Author(s):  
W.L. Lowther

The effects of inoculation and pelleting, with two storage periods, were investigated on the establishment of 'Grasslands Maku' Lotus pedunculatus at three sites. When seeds were sown one day after treatment, none of the treatments gave consistently better establishment than inoculationonly, although the addition of gum arabic adhesive alone significantiy increased establishment on one site. However, after 15-day storage of the seed, establishment was higher from gum arabic adhesive alone than from inoculated-only seed although the effect attained significance on only two sites. In contrast, establishment of pelleted seed, apart from rock-phosphate/dolomite on one site, was similar to or less than that from inoculated-only seed. There was a consistent trend for all pelleting treatments to give a lower degree of establishment than did gum arabic adhesive alone. Lotus dry matter production in the second growing season was measured on one site and the importance of maximizing establishment was demonstrated by the marked treatment effects on lotus yield.


Author(s):  
W.R. Ritchie

The Agricultural Machinery Research Centre, Massey University, undertook pasture renovation with a prototype direct drill at several North Island sites. Banded herbicide application was found to provide an effective medium term (two years) means of introducing ryegrass and clover species into browntop dominant pastures being intensively grazed. Specialist pasture species were introduced into Northland dairy pastures by band spraying and direct drilling. Wana cocksfoot and Pawera red clover were slower to establish than Nui and Ellett ryegrass. All species contributed to greater herbage dry matter production of the sward than the control and appeared to be persisting competitively. Keywords: Direct drilling, overdrilling, band spraying, winged opener, inverted T slot, pasture renewal, pasture renovation, prototype direct drill, Northland, Taranaki, Manawatu, no-tillage.


1996 ◽  
Vol 76 (2) ◽  
pp. 117-123 ◽  
Author(s):  
K. Broersma ◽  
N. G. Juma ◽  
J. A. Robertson

Proper management of crops on Gray Luvisols requires knowledge of net soil N mineralization during the growing season. Soil samples from a long-term field experiment at Beaverlodge, Alberta, were used to determine the kinetics of net N mineralization in soil samples from different crop rotations. The cropping systems established in 1968 consisted of (i) continuous barley (Hordeum vulgare L.) (CB); (ii) barley–forage (BF) [bromegrass (Bromus inermis Leyss.) and red clover (Trifolium pratense L.)]; (iii) continuous bromegrass (CG); and (iv) continuous legume (red clover) (CL.). The BF rotation was generally alternated every 3 yr, and each phase of the rotation (BF and BF) was present in every year. Soil samples from each cropping system were sampled to a depth of 15 cm in 1984. Net N mineralized during a 20-wk laboratory incubation at 30 °C and optimum moisture ranged from 32 to 207 mg kg−1 soil and followed the trend BF < CB = CG = BF < CL. The potentially mineralizable N (N0) ranged from 29 to 364 mg kg−1 soil; the mineralization rate constant (k) ranged from 0.04 to 0.26 wk−1; and the ratio of N0 to total N (active fraction) ranged from 1.1 to 11.4%. The net N mineralization rate of CL soil was 10-fold greater than that of the other cropping systems at the end of 20 wk of incubation. This suggests that the CL cropping system provides more N than other cropping systems during the growing season. Results support the observation that forages improve the N-supplying power of Gray Luvisols. Key words: Gray Luvisol, Typic Cryoboralf, N mineralization potential, cropping rotations, active N fraction


1980 ◽  
Vol 2 (2) ◽  
pp. 162 ◽  
Author(s):  
JC Scanlan

The response of Asr~ebla (Mitchell grass) grasslands to burning was determined in relation to the amount of rainfall re- ceived in the following growing season. Nine A. lappacea and three A. pecrinata locations in north-west Queensland were studied [:or both species, fire tended to increase the number and total dry weight of new tillers, although the individual tillers were smaller. Very low and very high rainfall resulted in sub-optimal new tiller formation in unburnt areas of A. lappacea. 1,lowering and seed set was also stimulated by wildfires. The nitrogen content of new tillers in burnt treatments was higher than for those in unburnt treatments under low growing season rainfall and lower under high growing season rainfall. Dry matter production from burnt A, lappacea, relative to unburnt areas, decreased under low rainfall and increased under high rainfall. Burning at a time of high soil moisture resulted in higher dry matter production and higher nitrogen content than burning during the spring period when soil moisture was low. The ecological and management implications of these responses are discussed


1975 ◽  
Vol 53 (4) ◽  
pp. 382-389 ◽  
Author(s):  
E. T. Kanemasu ◽  
C. K. Hiebsch

Canopy net carbon dioxide exchange (NCE) rates are needed to understand the effect of light on crop growth and development. NCE rates of sorghum, soybean, and wheat canopies were determined using field chambers and an infrared gas analyzer throughout a growing season. Whereas sorghum attained peak NCE rates early in season, soybean and wheat did not reach maximum rates until the late reproductive growth stage. Frequently during the season, NCE rates of sorghum were nearly four times those of soybeans and wheat. Solar radiation had a much greater affect on the NCE of sorghum than on that of soybeans. Apparent light saturation was observed in both soybeans and wheat. An expression for dry matter production of sorghum was derived using chamber data. The expression simulated the total dry matter production for sorghum in 1973, 1972, and 1970 within 20%.


Author(s):  
R.J.M. Hay ◽  
R.W. Kelly ◽  
D.L. Ryan

Grazing experiments investigating some factors determining the dry matter production and oestrogenicity of Pawera red clover are described. The legume content of the summer dry matter yield was double that of Ruanui and Huia pasture following overdrilling of lightly paraquated pasture with 4 or 8 kg/ha of Pawera. Persistence of Pawera was demonstrated by its ability to survive in sufficient density under grazing to contribute 35% of total summer dry matter production in its fourth year after direct drilling into lightly paraquated pasture. A Pawera sward when overdrilled with Tama ryegrass or Rahu ryecorn produced the same annual yield as Ariki/ Huia pasture, but the seasonal distribution was markedly different, with production from the overdrilled Pawera being greater in winter and summer. Pure Pawera swards produced some 70% more dry matter during December-February than Ariki/Huia pasture. The significance of this is related to conservation practices in Southland. Oestrogenicity of pure swards of Pawera was determined by measuring the cervical mucus response in ovariectomized ewes. Responses to grazing were equivalent to a single injection of 9 to 31 ug of oestradiol-17B


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