scholarly journals Biomass Production and Potential Fixed Nitrogen Inputs from Leguminous Cover Crops in Subtropical Avocado Plantations

Agronomy ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 70
Author(s):  
Terry J. Rose ◽  
Lee J. Kearney
Keyword(s):  
Biomass Production ◽  
White Clover ◽  
Cover Crops ◽  
Persea Americana ◽  
N Fixation ◽  
N Losses ◽  
N Accumulation ◽  
Tree Crop ◽  
Nitrogen Inputs ◽  
Legume Cover Crops

Nitrogen (N) fertiliser is applied to perennial horticultural crops to increase yields, but subsequent N losses in subtropical plantations may be high due to intense rainfall and warmer temperatures. While legume cover crops could potentially contribute N to the tree crops and reduce fertiliser-N requirements, few studies have quantified potential fixed-N inputs from cover crops legumes in tropical or subtropical tree crop systems. To address this, we investigated growth and N fixation of summer-growing Pinto peanut (Arachis pintoi Krapov. & W. C. Greg cv. Amarillo) and winter/spring dominant white clover (Trifolium repens L. cv. Haifa) grown as a mixed species cover crop in two commercial subtropical avocado (Persea americana Mill. cv. Hass) plantations. Legume biomass was assessed prior to mowing of the inter-row (fortnightly in summer and every 6–8 weeks over winter) and N fixation was estimated using the 15N natural abundance technique. Biomass production was 7377 kg ha−1 (930 kg ha−1 for white clover and 6447 kg ha−1 for Pinto peanut) at the first site over the 14-month period from December 2014 to January 2016, and 4467 kg ha−1 (1114 kg ha−1 for white clover and 3353 kg ha−1 for Pinto peanut) at the second site over the same period. Estimation of N fixation was not possible at the first site, due to a lack of difference in isotopic discrimination between the legume shoots and the reference plant (kikuyu (Pennisetum clandestinum Chiov.)) material. While legume shoots accumulated 157 kg N ha−1 (38 kg ha−1 for white clover and 119 kg ha−1 for Pinto peanut) across the season at site 1, the % N derived from atmosphere (%Ndfa) in legumes was relatively low (50–60% in Pinto peanut during the warmer months and around 30% in autumn and early spring, and from 13 % in April to 69% in September for white clover). The low %Ndfa in the legumes may have been due to low rainfall or molybdenum (Mo) deficiency. Ultimately the legume cover crops contributed an estimated 50 kg fixed N ha−1, which could partially offset fertiliser N requirements of the tree crop. Our results demonstrate the need to quantify N fixation in legume cover crops to assess potential N benefits as opposed to relying on typical measurements of legume biomass and N accumulation.

Benefits of winter legume cover crops require early sowing

2008 ◽  
Vol 59 (12) ◽  
pp. 1156 ◽  
Author(s):  
A. Gselman ◽  
B. Kramberger
Keyword(s):  
Cover Crops ◽  
Dry Matter ◽  
Control Treatment ◽  
N Fixation ◽  
Sowing Time ◽  
Mineral N ◽  
Late Autumn ◽  
Legume Cover Crops ◽  
Winter Cover ◽  
Winter Cover Crops

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.

scholarly journals Productivity and nitrogen benefits of late-season legume cover crops in organic wheat production

2014 ◽  
Vol 94 (4) ◽  
pp. 771-783 ◽  
Author(s):  
Harun Cicek ◽  
Martin H. Entz ◽  
Joanne R. Thiessen Martens ◽  
Paul R. Bullock
Keyword(s):  
Biomass Production ◽  
Cover Crops ◽  
Crop Production ◽  
N Uptake ◽  
Red Clover ◽  
Reduced Tillage ◽  
Sweet Clover ◽  
Wheat Production ◽  
Late Season ◽  
Legume Cover Crops

Cicek, H., Entz, M. H., Thiessen Martens, J. R. and Bullock, P. R. 2014. Productivity and nitrogen benefits of late-season legume cover crops in organic wheat production. Can. J. Plant Sci. 94: 771–783. When full-season cover crops are used in stockless organic rotations, cash crop production is compromised. Including winter cereals in rotations can widen the growing season window and create a niche for late-season cover crops. We investigated the establishment and biomass production of relay-cropped red clover (Trifolium pratense L.) and sweet clover (Melilotus officinalis L. ‘Norgold’) and double-cropped cowpea (Vigna unguiculata L. ‘Iron and Clay’), hairy vetch (Vicia villosa L.), lentil (Lens culinaris L. ‘Indianhead’), soybean (Glycine max L. ‘Prudence’), pea (Pisum sativum L. ‘40-10’), and oil seed radish (Raphanus sativus L.) as well as wheat response to these crops under reduced tillage (RT) and conventional tillage (CT) at three locations in Manitoba, Canada. Red clover, sweet clover and pea produced from 737 to 4075 and 93 to 1453 and 160 to 2357 kg ha−1of biomass, respectively. All double crops, with the exception of soybean at 2 site years, established successfully under both RT and CT. The presence of cover crops increased wheat N uptake at stem elongation, maturity and yield, even when the biomass production of cover crops was modest. We conclude that late-season cover crops enhance the following wheat yield and facilitate reduced tillage in organic crop production.

scholarly journals Nitrogen inputs and losses in response to chronic CO<sub>2</sub> exposure in a sub-tropical oak woodland

2014 ◽  
Vol 11 (1) ◽  
pp. 61-106 ◽  
Author(s):  
B. A. Hungate ◽  
B. D. Duval ◽  
P. Dijkstra ◽  
D. W. Johnson ◽  
M. E. Ketterer ◽  
...  
Keyword(s):  
Elevated Co2 ◽  
Atmospheric Co2 ◽  
15N Tracer ◽  
Carbon Limitation ◽  
N Fixation ◽  
Oak Woodland ◽  
N Losses ◽  
Co2 Concentrations ◽  
Nitrogen Inputs ◽  
Atmospheric Co2 Concentrations

Abstract. Rising atmospheric CO2 concentrations could alter the nitrogen (N) content of ecosystems by changing N inputs and N losses, but responses vary in field experiments, possibly because multiple mechanisms are at play. We measured N fixation and N losses in a subtropical oak woodland exposed to 11 yr of elevated atmospheric CO2 concentrations. We also explored the role of herbivory, carbon limitation, and competition for light and nutrients in shaping response of N fixation to elevated CO2. Elevated CO2 did not significantly alter gaseous N losses, but lower recovery and deeper distribution in the soil of a long-term 15N tracer indicated that elevated CO2 increased leaching losses. Elevated CO2 had no effect on asymbiotic N fixation, and had a transient effect on symbiotic N fixation by the dominant legume. Elevated CO2 tended to reduce soil and plant concentrations of iron, molybdenum, phosphorus, and vanadium, nutrients essential for N fixation. Competition for nutrients and herbivory likely contributed to the declining response N fixation to elevated CO2. These results indicate that positive responses of N fixation to elevated CO2 may be transient, and that chronic exposure to elevated CO2 can increase N leaching. Models that assume increased fixation or reduced N losses with elevated CO2 may overestimate future N accumulation in the biosphere.

scholarly journals Combining Legume Groundcovers and Low Nitrogen Fertilization in a Short-rotation Fraser Fir (Abies fraseri) Cropping System: Effect on Productivity, Soil Fertility, and Nutrient Leaching

HortScience ◽  
2011 ◽  
Vol 46 (3) ◽  
pp. 481-486 ◽  
Author(s):  
Yingqian Lin ◽  
Alexa R. Wilson ◽  
Pascal Nzokou
Keyword(s):  
White Clover ◽  
Cover Crops ◽  
Growth Response ◽  
Production Systems ◽  
Cropping Systems ◽  
Cropping System ◽  
N Leaching ◽  
Abies Fraseri ◽  
Nitrate N ◽  
Legume Cover Crops

High rates of inorganic fertilizers are used in conventional intensive production systems such as Abies fraseri (fraser fir) cropping systems for Christmas trees. Groundcovers can be used as green mulches, help reduce the use of farm chemicals, and provide several environmental benefits. We investigated the performance of a low-input cropping system by combining two legume cover crops [Dutch white clover (Trifolium repens) and alfalfa (Medicago sativa)] in combination with low rates of inorganic fertilizers as a step toward a more sustainable production system. The randomized block design comprised one cover crop and one of three applications of reduced rate inorganic fertilizer (75%, 50%, and 25% of the recommended rate). A conventional system using herbicides for weed control and the 100% rate of inorganic fertilizer was used as a control. Parameters measured included tree morphology, foliar nitrogen concentration, soil mineral nitrogen, and nitrate-N leaching below the root zone. A significant positive growth response (height and diameter) was obtained in all alfalfa-based cropping systems. This was accompanied by foliar nutrient concentrations similar to conventional plots and a reduction in nitrate-N leaching. However, in white clover-based cropping systems, the growth response was reduced (both height and diameter), suggesting competition for soil resources. In addition, the total nitrate-N leaching was higher in this system, suggesting an imbalance between mineral nitrogen availability and use in white clover-based cropping systems. We conclude that if the potential competition between cover crops and trees can be properly managed, legume cover crops can be effectively used to make intensive production tree-based systems more sustainable. Further studies related to mineralization and macronutrient flows are needed before any definite recommendation can be made about the use of these systems in large-scale production systems.

Increased nitrogen retention by cover crops: implications of planting date on soil and plant nitrogen dynamics

2019 ◽  
Vol 35 (6) ◽  
pp. 720-729
Author(s):  
Yangxue Zhou ◽  
Lindsey Roosendaal ◽  
Laura L. Van Eerd
Keyword(s):  
Cover Crops ◽  
Cover Crop ◽  
Management Practices ◽  
Planting Date ◽  
Temperate Climate ◽  
Limited Information ◽  
Available Nitrogen ◽  
N Losses ◽  
N Accumulation ◽  
N Dynamics

AbstractCover crops are frequently adopted to immobilize residual nitrogen post-harvest, thereby reducing potential N losses. However, the effectiveness of a cover crop depends on the species planting date, and other management practices. Limited information on N dynamics in cover crop systems is available specially in short-season vegetable rotations under temperate climate. From 2008 to 2010, a split-plot field experiment was carried out in a humid, temperate climate with cover crop treatment as the main plot factor [no cover crop control (NoCC), cereal rye, hairy vetch, oat, forage pea, oilseed radish (OSR) and a control with fertilizer N to the cucumber crop (NoCC + N)], and cover crop planting date as the split factor (early and late) to evaluate their impacts on cover crop biomass and N dynamics over the fall and following cucumber crop. All cover crop treatments significantly lowered soil mineral nitrogen (SMN) by 39–87% compared to the NoCC control, which was concomitant with cover crop growth and N accumulation. In the fall, SMN (0–90 cm depth) was less under the early-planted cover crops (avg. 78 kg N ha−1) compared to the late-planted (avg. 100 kg N ha−1). In April, greater plant available nitrogen (PAN, sum of SMN to 60 cm depth and plant N) with cover crops than without demonstrated N conservation over the winter and into the cucumber crop. Crop yield was equal to or better with a cover crop compared with the NoCC in both years; moreover, compared to the NoCC + N control yields were equivalent with OSR and pea. Oat, vetch and pea cover crops benefited the most by having an earlier planting date, while OSR and rye are recommended if the planting date is delayed. Although an early August planting date significantly increased plant N accumulation and SMN by November, this species-dependent interaction did not persist into the following season in yield and N accounted for in the system.

scholarly journals A Small Amount of Nitrogen Transfer from White Clover to Citrus Seedling via Common Arbuscular Mycorrhizal Networks

Agronomy ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 32
Author(s):  
Linfa Fang ◽  
Xinhua He ◽  
Xueliang Zhang ◽  
Yehua Yang ◽  
Rui Liu ◽  
...  
Keyword(s):  
White Clover ◽  
Cover Crops ◽  
Root Exudation ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Nitrogen Transfer ◽  
N Transfer ◽  
N Accumulation ◽  
N Nutrition ◽  
Mycorrhizal Networks

Few studies have examined if perennial leguminous cover crops are able to transfer nitrogen (N) via common mycorrhizal networks (CMNs) to neighboring fruit trees; the gradient of such N transfer could affect the N nutrition of both plants. Using separated three-column chambers to grow plants in a greenhouse, 99 atom% 15N as (15NH4)2SO4 was applied to leaves of white clover (Trifolium repens L.) and 15N was then traced in neighboring citrus (Citrus sinensis (L.) Osbeck) seedlings interconnected by an arbuscular mycorrhizal fungus (AMF, Rhizophagus intraradices). A range of 66.85–68.74% mycorrhizal colonization in white clover (mycorrhizal and/or Rhizobium trifolii inoculated) and 19.29–23.41% in citrus (non-mycorrhizal inoculated) was observed after 12 months of AMF inoculation in the white clover, indicating a successful CMN linkage was established between these two plant species. This CMN establishment resulted in significant increases in biomass, N accumulation, and 15N content of citrus when accompanied with nodulated and mycorrhizal fungus colonized white clover. N transfer from white clover to citrus was significantly greater under nodulation plus mycorrhization (46.23 mg N per pot, 1.71% of N transferred) than under non-inoculated control (4.36 mg N per pot, 0.21% of N transferred), and higher than sole mycorrhization (36.34 mg N per pot, 1.42% of N transferred). The percentage of N in citrus derived from white clover under nodulated/mycorrhization was 1.83–1.93%, and was highest in leaves (3.31%), moderate in stems (2.47%), and lowest in roots (0.41%) of citrus. In summary, results from this experiment demonstrated that nearly 2.0% of N transferred from white clover to citrus via CMN. Further studies are needed to quantify N transfer between white clover and citrus by other routes, including soil or root exudation pathways.

scholarly journals Management of clover in grazed pastures: expectations, limitations and opportunities

1996 ◽  
Vol 6 ◽  
pp. 55-64
Author(s):  
D.F. Chapman ◽  
A.J. Parsons ◽  
S. Schwinning
Keyword(s):  
White Clover ◽  
Nutritive Value ◽  
Self Regulation ◽  
Daily Intake ◽  
Metabolic Efficiency ◽  
N Fixation ◽  
N Availability ◽  
Intake Rate ◽  
Nitrogen Inputs ◽  
Clover Content

The value of white clover as a component of New Zealand pastures is undeniable, but it is also widely recognised that clover has limitations as a pasture plant and that these can lead to inefficiencies in the performance of grass/clover associations. This paper identifies some of the limitations to optimising the contribution of clover in complex soil/pasture/animal systems, within the context of the expectations commonly held of clover. Limitations to exploiting the greater digestive efficiency and short-term intake rate of clover compared to grass when they are grown in a mixture include animal behaviour responses that sometimes impose a restriction on total daily intake of nutrients, and the fact that clover often constitutes less than 20% of the pasture. Nitrogen inputs and yield advantages are also restricted by the low clover content of pastures. A simulation model is used to analyse the co-existence of grass and clover as influenced by N dynamics. This model explains the basis for selfregulation by grass/clover mixtures of the amount of mineral N in the soil. Self-regulation minimises N losses from mixtures, but the dynamic response of grass and clover to N availability also means that there may only be limited scope for increasing the overall clover content, or decreasing the spatial heterogeneity in clover distribution, of a mixture. Managing grass/clover associations to realise the benefits of white clover therefore means manipulating a complex system, where the outcomes of manipulation depend as much on the response of the companion grass as on the response of the clover itself. Opportunities for attaining a higher clover content in pastures include: manipulating the preferences of animals for clover versus grass; spatially separating grass and clover within fields; increasing the metabolic efficiency of N fixation in clover; uncoupling the apparent link between rhizobium symbiosis and the N content of clover leaves; and modifying the stolon morphology of clover as a way of increasing clover presence in favourable microsites within the pasture. Keywords: genetic improvement, grass/clover competition, grazing behaviour, intake, models, N fixation, nitrogen dynamics, nutritive value

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
Keyword(s):  
Soil Water ◽  
Cover Crops ◽  
Cover Crop ◽  
Farming Systems ◽  
N Fixation ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Mineral N ◽  
Legume Cover Crops ◽  
Chemical Fallow

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.

scholarly journals Pasture nematodes: the major scourge of white clover

2000 ◽  
pp. 195-199 ◽  
Author(s):  
R.N. Watson ◽  
C.F. Mercer
Keyword(s):  
White Clover ◽  
Management Practices ◽  
Research Programme ◽  
N Fixation ◽  
Production Potential ◽  
Pasture Production ◽  
Plant Feeding ◽  
Nitrogen Inputs ◽  
The Impact ◽  
Selection Of

This paper reviews current research within AgResearch to reduce the impact of plant-feeding nematodes. Plant-feeding nematodes reduce pasture production by around 15% annually, mainly through their effect on white clover. Nematicide application increases clover yields in pasture by an average 40% and N-fixation levels by over 50%. The problem occurs nationally. When pasture nematode burdens are reduced in established or newly sown ryegrass-white clover pasture, white clover can generally assume dominance during periods of active plant growth. The impact of clover nematodes in reducing nitrogen inputs and forage quality is estimated to exceed $1 billion annually in lost production potential. A gain of 1% in clover performance applied nationally is estimated to be worth up to $48 million. The research programme on pasture nematodes conducted within AgResearch has included evaluation of management practices that may reduce nematode impacts, selection of white clover seedlines for resistance or tolerance to nematodes, and identification of agents for biological control of nematodes within New Zealand pastures. Keywords: clover nematodes, Heterodera trifolii, impacts, Meloidogyne trifoliophila, M. hapla, Pratylenchus spp., Trifolium repens

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