Can legumes provide greater benefits than millet as a spring cover crop in southern Queensland farming systems?

2017 ◽  
Vol 68 (8) ◽  
pp. 746
Author(s):  
E. M. Wunsch ◽  
L. W. Bell ◽  
M. J. Bell

Cover crops grown during fallows can increase organic matter inputs, improve soil surface cover to reduce erosion risk, and enhance rainfall infiltration. An experiment compared a chemical fallow control with six different cover crops terminated at either 60 or 90 days after sowing. The commercial choice of millet (Echinochloa esculenta) was compared with two summer legumes (lablab (Lablab purpureus) and soybean (Glycine max)), and three winter legumes (field pea (Pisum sativum), faba bean (Vicia faba) and common vetch (Vicia sativa)). Cover crop biomass growth, atmospheric nitrogen (N) fixation, surface residue cover, and soil water and mineral N dynamics during the growth period and subsequent fallow were measured. Soil water and N availability and yield of wheat crops following the experimental treatments were simulated over a 100-year climate record using APSIM. Both experiments and simulations found the legumes inferior to millet as spring-sown cover crops, because they were slower to accumulate biomass, required later termination and provided groundcover that was less persistent, resulting in lower soil water at the end of the fallow. After 90 days of growth, the summer legumes, lablab and soybean, produced the most biomass and fixed more N (up to 25 kg N/ha) but also extracted the most soil water and mineral N. Legume N fixation was low because of high soil mineral N status (>100 kg N/ha) and occurred only when this had been depleted. At the end of the subsequent fallow in April, soil water was 30–60 mm less and soil mineral N 80–100 kg/ha less after both millet and 90-day terminated summer legume cover crops than the chemical fallow control. Simulations predicted soil-water deficits following legume cover crops to be >50 mm in the majority of years, but soil mineral N was predicted to be lower (median 80 kg N/ha) after millet cover crops. In conclusion, monoculture legume cover crops did not provide advantages over the current commercial standard of millet, owing to less effective provision of groundcover, low N fixation and possibly delayed release of N from residues. Further work could explore how legumes might be more effectively used as cover crops to provide N inputs and soil protection in subtropical farming systems.

HortScience ◽  
2010 ◽  
Vol 45 (1) ◽  
pp. 61-70 ◽  
Author(s):  
Emily R. Vollmer ◽  
Nancy Creamer ◽  
Chris Reberg-Horton ◽  
Greg Hoyt

Cover crops of foxtail millet ‘German Strain R’ [Setaria italica (L.) Beauv.] and cowpea ‘Iron & Clay’ [Vigna unguiculata (L.) Walp.] were grown as monocrops (MIL, COW) and mixtures and compared with a bare ground control (BG) for weed suppression and nitrogen (N) contribution when followed by organically managed no-till bulb onion (Allium cepa L.) production. Experiments in 2006–2007 and 2007–2008 were each conducted on first-year transitional land. Mixtures consisted of cowpea with high, middle, and low seeding rates of millet (MIX-70, MIX-50, MIX-30). During onion production, each cover crop treatment had three N rate subplots (0, 105, and 210 kg N/ha) of surface-applied soybean meal [Glycine max (L.) Merrill]. Cover crop treatments COW and BG had the greatest total marketable onion yield both years. Where supplemental baled millet was applied in 2006–2007, onion mortality was over 50% in MIL and MIX and was attributed to the thickness of the millet mulch. Nitrogen rates of 105 and 210 kg N/ha increased soil mineral N (NO3– and NH4+) on BG plots 2 weeks after surface application of soybean meal each year, but stopped having an effect on soil mineral N by February or March. Split applications of soybean meal could be an important improvement in N management to better meet increased demand for N uptake during bulb initiation and growth in the spring.


2008 ◽  
Vol 59 (12) ◽  
pp. 1156 ◽  
Author(s):  
A. Gselman ◽  
B. Kramberger

Winter cover crops are beneficial, especially legumes that can supply nitrogen (N) to the next crop. The purpose of this study, involving separate experiments carried out at 2 different locations in north-eastern Slovenia, was to determine the most appropriate sowing time (early, early autumn SD1; late, mid autumn SD2; very late, late autumn SD3) for winter legumes (Trifolium subterraneum L., T. incarnatum L., T. pratense L., and Vicia villosa Roth) for the optimal yield of beneficial dry matter and soil N cycling. The control treatment used Lolium multiflorum Lam. For legume cover crops in SD1, from 915.0 (T. subterraneum) to 2495.0 (V. villosa) kg herbage dry matter yield (HDMY)/ha, 52.3 (T. pratense) to 148.4 (T. incarnatum) kg accumulated N (AN)/ha, and 14.5 (T. pratense) to 114.5 (T. incarnatum) kg symbiotically fixed N (Nsymb)/ha was obtained to the end of autumn. Until the spring ploughing-in, which was before maize sowing, legume cover crops in SD1 yielded 1065.0 (T. subterraneum) to 4440.0 (T. incarnatum) kg HDMY/ha, 74.9 (T. subterraneum) to 193.0 (V. villosa) kg AN/ha, and 4.7 (T. subterraneum) to 179.0 (V. villosa) kg Nsymb/ha. All parameters in SD2 were significantly lower than in SD1, whereas the SD3 sowing was not suitable for the legumes. The benefits of legume winter cover crops with regard to symbiotic N fixation were achieved only by early sowing; however, the amount of soil mineral N in late autumn and in early spring was decreased under L. multiflorum more than under the legumes.


2017 ◽  
Vol 68 (1) ◽  
pp. 11 ◽  
Author(s):  
Lindsay W. Bell ◽  
John Lawrence ◽  
Brian Johnson ◽  
Mark B. Peoples

Several new and existing short-term forage legumes could be used to provide nitrogen (N) inputs for grain crops in subtropical farming systems. The fixed-N inputs from summer-growing forage legumes lablab (Lablab purpureus), burgundy bean (Macroptilium bracteatum) and lucerne (Medicago sativa) and winter-growing legume species snail medic (Medicago scutellata), sulla (Hedysarum coronarium) and purple vetch (Vicia benghalensis) were compared over several growing seasons at four locations in southern Queensland, Australia. Available soil mineral N and grain yield of a following cereal crop were compared among summer-growing legumes and forage sorghum (Sorghum spp. hybrid) and among winter-growing legumes and forage oats (Avena sativa). In the first year at all sites, legumes utilised the high initial soil mineral N, with <30% of the legume N estimated to have been derived from atmospheric N2 (%Ndfa) and legume-fixed N <30 kg/ha. In subsequent years, once soil mineral N had been depleted, %Ndfa increased to 50–70% in the summer-growing legumes and to 60–80% in winter-growing legumes. However, because forage shoot N was removed, rarely did fixed N provide a positive N balance. Both lablab and burgundy bean fixed up to 150 kg N/ha, which was more than lucerne in all seasons. Prior to sowing cereal grain crops, soil nitrate was 30–50 kg/ha higher after summer legumes than after forage sorghum. At one site, lablab and lucerne increased the growth and yield of a subsequent grain sorghum crop by 1.4 t/ha compared with growth after forage sorghum or burgundy bean. Of the winter-growing legumes, sulla had the highest total N2 fixation (up to 150 kg N/ha.year) and inputs of fixed N (up to 75 kg N/ha), and resulted in the highest concentrations of soil N (80–100 kg N/ha more than oats) before sowing of the following crop. Wheat protein was increased after winter legumes, but there was no observed yield benefit for wheat or grain sorghum crops. New forage legume options, lablab, burgundy bean and sulla, showed potential to increase N supply in crop rotations in subtropical farming systems, contributing significant fixed N (75–150 kg/ha) and increasing available soil N for subsequent crops compared to non-legume forage crops. However, high soil mineral N (>50 kg N/ha) greatly reduced N2 fixation by forage legumes, and significant N2 fixation only occurred once legume shoot N uptake exceeded soil mineral N at the start of the growing season. Further work is required to explore the impact of different management strategies, such as livestock grazing rather than harvesting for hay, on the long-term implications for nutrient supply for subsequent crops.


1998 ◽  
Vol 131 (3) ◽  
pp. 299-308 ◽  
Author(s):  
G. S. FRANCIS ◽  
K. M. BARTLEY ◽  
F. J. TABLEY

Two field experiments in Canterbury, New Zealand, were conducted during 1993–95 following the ploughing of temporary pasture leys. These experiments investigated the effects of cover crop management on the accumulation of soil mineral N and nitrate leaching during winter, and the growth and N uptake of the following spring cereal crop. The cover crops used were ryegrass (Lolium multiflorum L.), oats (Avena sativa L.), lupins (Lupinus angustifolius L.), mustard (Sinapis alba L.) and winter wheat (Triticum aestivum).Ploughing of temporary pasture in autumn (March) resulted in extensive net N mineralization of organic N by the start of winter (June). In fallow soil, mineral N in the profile in June ranged from 98 kg N/ha in 1993 to 128 kg N/ha in 1994. When cover crops were established early in the autumn (March) in 1993, both the above-ground dry matter production (1440–3108 kg DM/ha) and its N content (50–71 kg N/ha) were substantial by the start of winter. In 1994, establishment of cover crops one month later (April) resulted in very little dry matter production and N uptake by June. In both years, compared with fallow soil, winter wheat planted in May had little effect on soil mineral N content by the start of winter.Compared with fallow, cover crops had little effect on soil drainage over winter. Cumulative nitrate leaching losses from fallow soil were much smaller in 1993 (23 kg N/ha) than in 1994 (49 kg N/ha), mainly due to differences in rainfall distribution. Cover crops reduced cumulative nitrate leaching losses in 1993 to 1–5 kg N/ha and in 1994 to 22–30 kg N/ha. When cover crops were grazed, soil mineral N contents were increased due to the return of ingested plant N to urine patch areas of soil. Elevated soil mineral N contents under grazing persisted throughout the winter. Grazing had little effect on cumulative nitrate leaching losses, mainly because of the small amount of drainage that occurred after grazing in either year.Compared with fallow, incorporation of large amounts of non-leguminous above ground dry matter depressed the yield and N uptake of the following spring-sown cereal crop. Where cover crops were grazed, yields of the following cereal crops were similar to those for soil fallow over the winter.


Agronomy ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 248 ◽  
Author(s):  
Cai Zhao ◽  
Zhilong Fan ◽  
Jeffrey A. Coulter ◽  
Wen Yin ◽  
Falong Hu ◽  
...  

Nitrogen (N) fixation is essential in the development of sustainable agriculture, but nodulation of legumes is usually inhibited by N fertilization. In this study, we evaluated the increased density of intercropped maize (Zea mays L.) as a means to alleviate the inhibitory effect of soil mineral N on intercropped pea (Pisum sativum L.) and improve system performance. A field experiment was conducted in the Hexi Corridor region of northwestern China from 2012 to 2014. The experiment consisted of monoculture pea, monoculture maize, and a pea/maize strip-intercropping system. Two levels of N fertilization were evaluated in both cropping systems during the co-growth period of intercropping, i.e., 0 kg N ha−1 (N0) and 135 kg N ha−1 (N1), and three maize densities were evaluated with both levels of N fertilization in the intercropping system, i.e., 45,000 plants ha−1 (D1), 52,500 plants ha−1 (D2), and 60,000 plants ha−1 (D3). The application of N reduced the number of nodules of intercropped pea by 135% at D1 and by 9% at D2 compared to no application of N, in all the years examined. The alleviation of the inhibitory effect of soil mineral N on the nodulation of intercropped pea (Cis) was calculated as the percentage increase in nodulation with intercropping relative to monoculture for a given level of N fertilization. With the application of N, Cis was improved by increased intercropped maize density (D3 > D2 > D1) at all stages. The internal efficiency of nitrogen (IEN) of pea was improved with intercropping and, on average, was 19% and 12% greater at D3 than at D1 and D2, respectively. These results demonstrate that increased maize density can alleviate the inhibitory effect of soil N on the nodulation of pea and sustain the productivity of maize/pea intercropping while reducing N fertilizer requirements in arid regions.


2000 ◽  
Vol 51 (1) ◽  
pp. 13 ◽  
Author(s):  
M. H. McCallum ◽  
M. B. Peoples ◽  
D. J. Connor

The nitrogen (N) dynamics (N2 fixation inputs, changes in soil mineral N and total N, N removed in agricultural produce) of a lucerne-based phase farming system (grazed lucerne–annual medic–ryegrass pastures grown in rotation with crops) was compared with that of continuous cropping (cereal, oilseed, and legume pulse crops) in the Victorian Wimmera. The contribution of biological N2 fixation to the N economy of these different systems was strongly linked to biomass production by the legume components of pastures, or field pea in the cropping sequence. The amount of fixed N present in field pea shoots or the total amount of N2 estimated to be fixed by the whole plant (shoots and roots) (121–175 kg N/ha.crop and 181–262 kg N/ha.crop, respectively) was generally greater than the combined measured annual inputs of fixed N by lucerne and annual medic during a pasture ley (40–95 kg N/ha.year in herbage, 80–190 kg N/ha.year in total plant), although large amounts of N were removed in the field pea grain at harvest (115–151 kg N/ha.crop). Over 2 years (1995–96), the seasonal rainfall patterns had a much larger impact on the growth, dry matter production, and N2 fixation of annual medic compared with lucerne. Winter-cleaning of ryegrass from the pasture before cropping resulted in a greater legume content in the pasture and generally increased amounts of fixed N in herbage (by up to 55 kg N/ha.year). Total soil N at depth (0.5–1.0 m) was significantly greater after 2–4 years of pasture than under continuous cropping. In one year (1996), the amount of soil mineral N following a winter-cleaned pasture was greater (by 32–45 kg N/ha, 0–1 m) than after either canola or wheat, producing a yield benefit in a subsequent canola crop that was equivalent to pre-drilling 46 kg N/ha as fertiliser. However, despite some improvements in N fertility, large crop responses to N fertiliser were still observed following pasture. Grain yield was increased by 0.33–0.55 t/ha in canola and by 1.0 t/ha in wheat, grain protein raised by 0.7–2.3% in canola and by 1.3% in wheat, and oil yield in canola enhanced by 124–205 kg/ha with pre-drilled applications of fertiliser N (46 kg/ha). It is speculated that more legume-dominant pastures (>80%) could provide greater flow-on N benefits to farming systems in the Wimmera than the mixed legume–grass swards used in the present study. However, it is likely that a need will remain for supplementary fertiliser N to optimise the nutrition of subsequent non-legume crops in the region.


2001 ◽  
Vol 10 (3) ◽  
pp. 197-208 ◽  
Author(s):  
H. KÄNKÄNEN ◽  
C. ERIKSSON ◽  
M. RÄKKÖLÄINEN

Cover crops can be used to reduce leaching and erosion, introduce variability into crop rotation and fix nitrogen (N) for use by the main crops. In Finland, undersowing is a suitable method for establishing cover crops in cereal cropping. The effect of annual undersowing on cereal grain yield and soil mineral N content in spring was studied at two sites. Red clover (Trifolium pratense L.), white clover (Trifolium repens L.), a mixture of red clover and meadow fescue (Festuca pratensis Huds.), and westerwold ryegrass (Lolium multiflorum Lam. var. westerwoldicum) were undersown in spring cereals in the same plots in six successive seasons, and their effects on cereal yield were estimated. Annual undersowing with clovers increased, and undersowing with westerwold ryegrass decreased cereal grain yields. The grain yield was only slightly lower with a mixture of red clover and meadow fescue than with red clover alone. Westerwold ryegrass did not affect soil mineral N content in spring and the increase attributable to clovers was small. The mixture of red clover and meadow fescue affected similarly to pure red clover. Soil fertility was not notably improved during six years of undersowing according to grain yield two years later.


2012 ◽  
Vol 59 (No. 1) ◽  
pp. 22-28 ◽  
Author(s):  
B. Kramberger ◽  
A. Gselman ◽  
M. Podvršnik ◽  
J. Kristl ◽  
M. Lešnik

To investigate the environmental advantages of using grass-clover binary mixtures over pure stands as winter cover crops, a serial of five field experiments (each designed as randomized complete blocks with four replicates) was carried out in eastern Slovenia. Trifolium incarnatum L. and Lolium multiflorum Lam. were sown in late summer as pure stands and binary mixtures. Pooled data calculated from all the experiments revealed that the soil mineral N in spring and accumulation of N by plants decreased with decreasing proportion of T. incarnatum in the binary mixtures, while the C:N ratio of cover crop organic matter increased. C accumulation was the highest when the seeding ratio of the binary mixture of T. incarnatum and L. multiflorum was 50:50. In the C and N environmentally sustainable management efficiency coefficients, three important traits of winter cover crops for environmental pro-tection were given equal importance (low soil mineral N content in spring, high C accumulation in plants, and high N accumulation in plants). The coefficient was higher for binary mixtures of T. incarnatum and L. multiflorum than for pure stands of these crops, proving the complex environmental advantages of binary mixtures over pure stands.


2000 ◽  
Vol 51 (7) ◽  
pp. 877 ◽  
Author(s):  
J. F. Angus ◽  
R. R. Gault ◽  
A. J. Good ◽  
A. B. Hart ◽  
T. D. Jones ◽  
...  

Growing dryland crops after lucerne is known to be risky because of the lack of residual soil water. We investigated ways of reducing this risk by removing portions of a lucerne pasture, using either herbicides or cultivation, at monthly intervals between November and April, before sowing a wheat crop in May, followed by a canola crop in the following year. The experimental site was on a red-brown earth in southern New South Wales. Lucerne removal was incomplete when the wheat was sown, so all lucerne plants were removed from half of each plot with a post-emergence herbicide, to allow comparisons of intercropped wheat–lucerne and wheat monoculture. Measurements were made on crop growth, yield, grain quality, soil water, and soil mineral nitrogen (N) before and after both crops. On average, each additional month between lucerne removal and wheat sowing led to a yield increase of 8% and a grain protein increase of 0.3 percentage units. The main reason for the increases was additional soil mineral N, associated with a longer period of mineralisation. The soil water content at the time of wheat sowing was greater with early lucerne removal but the growing season rainfall did not limit yields, and there was more residual soil water at the time of wheat maturity where lucerne had been removed late and yields were lower. Method of lucerne removal did not significantly affect wheat yield, grain protein, soil water, or soil mineral N. The portions of the plots containing lucerne plants that survived the initial removal attempt produced similar wheat yields to the portions where lucerne had been totally removed, but grain protein was lower. The following growing season was drier, but despite less residual soil water where lucerne had been removed earlier in the previous year, the average canola yield was 2.5% greater for each additional month of fallow. The increase again appeared to be due to more residual mineral N. The seed oil concentration also decreased in response to later lucerne removal but seed protein increased. Where lucerne plants had been retained in the previous wheat crop, canola yield was lower than where they had been totally removed, apparently because of less soil water at sowing. Over the 2 years of the experiment, the net supply of mineral N was 374 kg N/ha, equivalent to an annual net mineralisation of 2% of the total soil N. The initial mineralisation rate was slow, suggesting that the soil may be deficient in mineral N soon after lucerne removal.


HortScience ◽  
1996 ◽  
Vol 31 (5) ◽  
pp. 758c-758
Author(s):  
David C. Ditsch ◽  
Richard T. Jones

High-value crops (tobacco and sweet corn) often receive high levels of N fertilizer during the growing season rather than risk yield and/or quality reductions. Following harvest, small-grain winter cover crops are sown to reduce soil erosion and recover residual fertilizer N. Fall cole crops, such as cabbage, grow rapidly in early fall, respond well to N fertilization, and have the potential to be sold for supplemental income. The objectives of this study were to 1) compare fall cabbage and winter rye as scavengers of residual fertilizer N and 2) determine if a relationship between fall soil mineral-N (NO–3 +) levels and fall cabbage yield response to N fertilization exists. Soil mineral N levels following sweet corn and tobacco ranged from 22 to 53 mg·kg–1 in the surface 30-cm and declined with depth. Fall cabbage appeared to be as effective as rye at reducing soil mineral N levels. No fall cabbage dry matter yield response to applied N was measured in 1993 and 1995. However, following sweet corn in 1994, a small cabbage yield response to N at 56 kg·ha–1 was measured when the soil mineral level, prior to fall fertilization, was 22 mg·kg–1.


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