scholarly journals Non-overwintering cover crops: a significant source of N

1997 ◽  
Vol 45 (2) ◽  
pp. 231-248 ◽  
Author(s):  
J.J. Schroder ◽  
L. Ten Holte ◽  
B.H. Janssen

In field experiments in 1982-89 at 2 sites in the Netherlands, potatoes cv. Bintje and sugarbeet cv. Monohil or Ovatio in a wheat/potatoes/wheat/sugarbeet rotation were preceded during winter by fallow or a green manure crop of Lolium multiflorum cv. Tetila with 0 (G0), 100 (G100) or 200 kg N/ha (G200) or Trifolium pratense cv. Rotra with no N (RC). Green manure crops were undersown to winter wheat cv. Durin and ploughed in in the first half of November. On average, G0, G100, G200 and RC had then accumulated 22, 93, 125 and 57 kg N/ha, respectively, in the above-ground plant parts. G0 crops tended to immobilize soil mineral N in spring and generally had non-significant effects on the yields of potatoes and sugarbeet, whereas G100, G200 and RC increased the N yields and marketable yields significantly. Effects were mainly attributable to the release of N by the green manures. The fertilizer value of the green manures was evaluated by their effect on economic optimum N rates, the marketable yield and the N yield when no mineral fertilizer N was supplied. The last two methods appeared to be most appropriate for the present experiments. Fertilizer values ranged from -21 to 108 kg N/ha, depending on the type of green manure crop and the calculation method. About half of the N accumulated in above-ground parts of the green manure crop was available to potatoes and sugarbeet from G100 when evaluated by its effect on N yields. From G200 this was even greater, although this may partly have resulted from the transfer of fertilizer N that had not been taken up by the green manure crop. Due to a high content of N in roots and stubble, RC provided, on average, almost double the amount of N accumulated in the above-ground plant parts. Green manure crops also had a minor positive effect on grain yields of winter wheat following potatoes and sugarbeet. At least 35% of the above-ground N in L. multiflorum green manure crops was not utilized within the first 18 months after their incorporation.

2020 ◽  
Vol 15 (4) ◽  
pp. 351-358
Author(s):  
K. Anny Mrudhula ◽  
Y. Suneetha

A field experiments was conducted during 2015 and 2016 to study the effect of green manures and phosphorus levels in blackgram crop at Agricultural College Farm, Bapatla. The experiment was conducted in split- split plot design on sandy clay loam soil with three main treatments three subtreatments to Kharif rice and three sub-sub treatments to Rabi crop. The treatments consisted of Dhaincha green manure crop, sunnhemp green manure crop and without green manure as main plot treatments and three phosphorus levels to rice crop comprising of 45 kg P2O5 ha-1, 60 kg P2O5 ha-1 and 75 kg P2O5 ha-1 as sub- plot treatments and are replicated thrice. The Rabi experiment was laid out on the same site in a split-split plot design without disturbing the soil for succeeding blackgram crop and each of the Kharif plot was divided into three sub-sub plots to receive three levels of phosphorus (No P, 50% RDP and 100% RDP) to each plot. Yield and economics of blackgram which received Dhaincha green manure incorporation with 75 kg P2O5 ha-1 to Kharif rice crop and 100% RDP to Rabi blackgram was recorded significantly higher and it was on a par with sunnhemp green manure incorporation with 75 kg P2O5 ha-1 to Kharif rice crop and 100% RDP to Rabi blackgram.


2012 ◽  
Vol 27 (1) ◽  
pp. 60-67 ◽  
Author(s):  
Steven J. Shirtliffe ◽  
Eric N. Johnson

AbstractOrganic farmers in western Canada rely on tillage to control weeds and incorporate crop residues that could plug mechanical weed-control implements. However, tillage significantly increases the risk of soil erosion. For farmers seeking to reduce or eliminate tillage, potential alternatives include mowing or using a roller crimper for terminating green manure crops (cover crops) or using a minimum tillage (min-till) rotary hoe for mechanically controlling weeds. Although many researchers have studied organic crop production in western Canada, few have studied no-till organic production practices. Two studies were recently conducted in Saskatchewan to determine the efficacy of the following alternatives to tillage: mowing and roller crimping for weed control, and min-till rotary hoeing weed control in field pea (Pisum sativum L.). The first study compared mowing and roller crimping with tillage when terminating faba bean (Vicia faba L.) and field pea green manure crops. Early termination of annual green manure crops with roller crimping or mowing resulted in less weed regrowth compared with tillage. When compared with faba bean, field pea produced greater crop biomass, suppressed weeds better and had less regrowth. Wheat yields following pea were not affected by the method of termination. Thus, this first study indicated that roller crimping and mowing are viable alternatives to tillage to terminate field pea green manure crops. The second study evaluated the tolerance and efficacy of a min-till rotary harrow in no-till field pea production. The min-till rotary hoe was able to operate in no-till cereal residues and multiple passes did not affect the level of residue cover. Field pea exhibited excellent tolerance to the min-till rotary hoe. Good weed control occurred with multiple rotary hoe passes, and pea seed yield was 87% of the yield obtained in the herbicide-treated check. Therefore, this second study demonstrated that min-till rotary hoeing effectively controls many small seeded annual weeds in the presence of crop residue and thus can reduce the need for tillage in organic-cropping systems.


Author(s):  
Robert P. Larkin

Crop rotations and the inclusion of cover crops and green manures are primary tools in the sustainable management of soil-borne diseases in crop production systems. Crop rotations can reduce soil-borne disease through three general mechanisms: (1) serving as a break in the host-pathogen cycle; (2) by altering the soil physical, chemical, or biological characteristics to stimulate microbial activity and diversity; or (3) directly inhibiting pathogens through the release of suppressive or toxic compounds or the enhancement of specific antagonists. Brassicas, sudangrass, and related plant types are disease-suppressive crops well-known for their biofumigation potential but also have other effects on soil microbiology that are important in disease suppression. The efficacy of rotations for reducing soil-borne diseases is dependent on several factors, including crop type, rotation length, rotation sequence, and use of the crop (as full-season rotation, cover crop, or green manure). Years of field research with Brassica and non-Brassica rotation crops in potato cropping systems in Maine have documented the efficacy of Brassica green manures for the reduction of multiple soil-borne diseases. However, they have also indicated that these crops can provide disease control even when not incorporated as green manures and that other non-biofumigant crops (such as barley, ryegrass, and buckwheat) can also be effective in disease suppression. In general, all crops provided better disease control when used as green manure vs. as a cover crop, but the addition of a cover crop can improve control provided by most rotation crops. In long-term cropping system trials, rotations incorporating multiple soil health management practices, such as longer rotations, disease-suppressive rotation crops, cover crops, and green manures, and/or organic amendments have resulted in greater yield and microbial activity and fewer disease problems than standard rotations. These results indicate that improved cropping systems may enhance productivity, sustainability, and economic viability.


Plant Disease ◽  
2016 ◽  
Vol 100 (9) ◽  
pp. 1910-1920 ◽  
Author(s):  
J. Himmelstein ◽  
J. E. Maul ◽  
Y. Balci ◽  
K. L. Everts

Fall-planted Vicia villosa or Trifolium incarnatum cover crops, incorporated in spring as a green manure, can suppress Fusarium wilt (Fusarium oxysporum f. sp. niveum) of watermelon. During cover crop growth, termination, and incorporation into the soil, many factors such as arbuscular mycorrhizae colonization, leachate, and soil respiration differ. How these cover-crop-associated factors affect Fusarium wilt suppression is not fully understood. Experiments were conducted to evaluate how leachate, soil respiration, and other green-manure-associated changes affected Fusarium wilt suppression, and to evaluate the efficacy of the biocontrol product Actinovate AG (Streptomyces lydicus WYEC 108). General and specific suppression was examined in the field by assessing the effects of cover crop green manures (V. villosa, T. incarnatum, Secale cereale, and Brassica juncea) on soil respiration, presence of F. oxysporum spp., and arbuscular mycorrhizal colonization of watermelon. Cover crop treatments V. villosa, T. incarnatum, and S. cereale and no cover crop were evaluated both alone and in combination with Actinovate AG in the greenhouse. Additionally, in vitro experiments were conducted to measure the effects of cover crop leachate on the mycelial growth rates of F. oxysporum f. sp. niveum race 1 and Trichoderma harzianum. Soil microbial respiration was significantly elevated in V. villosa and Trifolium incarnatum treatments both preceding and following green manure incorporation, and was significantly negatively correlated with Fusarium wilt, suggesting that microbial activity was higher under the legumes, indicative of general suppression. Parallel to this, in vitro growth rates of F. oxysporum f. sp. niveum and Trichoderma harzianum on V. villosa leachate amended media were 66 and 213% greater, respectively, than on nonamended plates. The F. oxysporum spp. population (based on CFU and not differentiated into formae specialis or races) significantly increased in V. villosa-amended field plots. Additionally, the percentage of watermelon roots colonized by arbuscular mycorrhizae following V. villosa and Trifolium incarnatum green manures was significantly higher than in watermelon following bare ground (58 and 44% higher, respectively). In greenhouse trials where cover crops were amended to soil, Actinovate AG did not consistently reduce Fusarium wilt. Both general and specific disease suppression play a role in reducing Fusarium wilt on watermelon.


Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1469
Author(s):  
Silke Deketelaere ◽  
Katrijn Spiessens ◽  
Sabien Pollet ◽  
Lien Tyvaert ◽  
Luc De Rooster ◽  
...  

Verticillium wilt is one of the most important diseases of cauliflower and can lead to serious economic losses. In this study, two complementary strategies were explored to employ the antagonistic capacity of Verticillium isaacii towards Verticillium wilt of cauliflower. The first strategy focused on introducing V. isaacii Vt305 by artificial inoculation of cauliflower plantlets at the nursery stage. Two inoculum types (spores and microsclerotia of V. isaacii Vt305) and different concentrations of microsclerotia were tested in greenhouse and field trials. Seed treatment with 500 microsclerotia seed−1 led to a satisfying biocontrol level of Verticillium wilt. In addition, the PHYTO-DRIP® system was successful in delivering the microsclerotia to cauliflower seeds. The second strategy relied on the stimulation of the natural V. isaacii populations by rotating cauliflower with green manures and potato. Four green manure crops and potato were tested during multiple field experiments. Although these crops seemed to stimulate the V. isaacii soil population, this increase did not result in a control effect on Verticillium wilt of cauliflower in the short term. Importantly, our results indicate that the use of green manures is compatible with the application of V. isaacii Vt305 as biocontrol agent of Verticillium wilt in cauliflower.


2020 ◽  
Vol 30 (6) ◽  
pp. 685-691
Author(s):  
Andre Luiz Biscaia Ribeiro da Silva ◽  
Joara Secchi Candian ◽  
Lincoln Zotarelli ◽  
Timothy Coolong ◽  
Christian Christensen

Soil nitrogen (N) is easily leached in cabbage (Brassica oleracea var. capitata) production areas of southeastern United States characterized by sandy soils with low water-holding capacity. Soil N leaching in these areas is increased after rainfall events; consequently, growers increase the fertilizer N application to protect against N deficiencies and yield loss. The objective of this study was to evaluate the effects of three fertilizer N rates on yield and head quality for common cabbage cultivars used by Florida and Georgia growers during four cabbage growing seasons. Field experiments were conducted in Hastings, FL, in 2016 and 2017, and in Tifton, GA, in 2018 and 2019. A randomized complete block design was used with a split-plot design of fertilizer N rate and cabbage cultivar. Fertilizer N rate treatments consisted of the application of 170, 225, and 280 lb/acre N and were assigned as the main plot. Cabbage cultivars Bravo, Bronco, Bruno, Capture, Cheers, and Ramada were assigned as the sub-plots. Weather conditions were monitored during all growing seasons, and total, marketable, and unmarketable yields, as well as cabbage head polar and equatorial diameters, and core height and width were measured. In Florida, there was a significant interaction for growing season and fertilizer N rate. The Florida 2016 cabbage season experienced 10.5 inches of rainfall, and fertilizer N rates had no effect on cabbage yields. Total and marketable yield averaged 45,391 and 38,618 lb/acre among fertilizer N rates in 2016, respectively. Rainfall accumulated 2.1 inches during the 2017 study in Florida, which was less than the crop evapotranspiration. In response, total and marketable yield were higher for the applications of 225 lb/acre N (51,865 and 49,335 lb/acre, respectively) and 280 lb/acre N (54,564 and 52,219 lb/acre, respectively) compared with the application of 170 lb/acre N (47,929 and 43,710 lb/acre, respectively). In Georgia, there were no significant interactions between production season and fertilizer N rates. In addition, there were no significant main effects of season or fertilizer N rate. Rainfall events accumulated 20.9 and 7.8 inches during the 2018 and 2019 growing seasons, respectively. Total and marketable yields averaged 37,290 and 33,355 lb/acre, respectively for the two growing seasons in Georgia. Cabbage cultivar had no interaction with fertilizer N rate in any location. ‘Cheers’ (52,706 lb/acre) had the highest total yield in Florida, and ‘Ramada’ (38,462 lb/acre) and ‘Bronco’ (39,379 lb/acre) had the highest total yields in Georgia. In conclusion, the application of 225 lb/acre N was sufficient to sustain cabbage yields, but yields of the 170- and 225-lb/acre N treatments were not different when rainfall events exceeded crop evapotranspiration.


EDIS ◽  
1969 ◽  
Vol 2003 (16) ◽  
Author(s):  
Jim Rich ◽  
David Wright ◽  
Jim Marois ◽  
Dick Sprenkel

Cover crops are generally planted after a primary (cash) crop for one or more of the following reasons: erosion control, organic matter accumulation, improved soil tilth, pest suppression (weed, disease, nematode, and insect), and nitrogen production. Optimally, a cover crop will provide a wide range of most or all of the previously mentioned benefits, even if the main reason for planting it was more specific. The eight cover/green manure crops described herein have been shown to provide several benefits to a succeeding crop. This document is ENY-688 (IN483), one of a series of the Department of Entomology and Nematology, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Publication Date: August 2003.


1993 ◽  
Vol 73 (1) ◽  
pp. 139-148 ◽  
Author(s):  
L. Townley-Smith ◽  
A. E. Slinkard ◽  
L. D. Bailey ◽  
V. O. Biederbeck ◽  
W. A. Rice

Both large-seeded annual legumes (pulse crops) and small-seeded annual or perennial legumes (forage crops) fix nitrogen (N) and can improve soil organic matter and fertility when used for green manuring. The role of pulses as green-manure crops has not been adequately evaluated in the Prairies, as they have been grown primarily as cash seed crops. An experiment was conducted in the Dark Brown soil zone at Saskatoon over four growing seasons on a moderately heavy-textured soil to determine the productivity, nitrogen fixation and soil moisture use of pea (Pisum sativum L. ’Trapper’), faba bean (Vicia faba L. ’Outlook’), lentil (Lens culinaris Medik. ’Eston’ and ’Indianhead’), Tangier flatpea (Lathyrus tingitanus L. ’Tinga’) and seedling alfalfa (Medicago sativa L. ’Moapa’) as green-manure substitutes for summerfallow. Dry-matter production (above ground) by full bloom averaged 6390, 4140, 3590, 2930 and 1260 kg ha−1 for pea, lentil, faba bean, Tangier flatpea and seedling alfalfa, respectively. Nitrogen yields were 166, 108, 119, 81 and 36 kg ha−1 and N fixation rates were 40, 15, 40, 24 and 4 kg ha−1 for pea, lentil, faba bean, Tangier flatpea and seedling alfalfa, respectively. Green-manure used similar amounts of water as wheat grown to maturity. Snow trapping by desiccating the standing green-manure crop was ineffective in increasing soil water in the spring. Low seeding rate and thus low cost of production made lentil the most reasonable choice as an annual-legume green-manure crop. However, improved methods of water conservation must be found to replace the water used to grow the green-manure crop. Key words: Pea, lentil, faba bean, Tangier flatpea, green manure, soil moisture


2016 ◽  
Vol 96 (5) ◽  
pp. 867-886 ◽  
Author(s):  
S.P. Mooleki ◽  
Y. Gan ◽  
R.L. Lemke ◽  
R.P. Zentner ◽  
C. Hamel

Green manure crops may have a role to play in the development of sustainable agricultural systems in the semiarid northern Great Plains of North America. This study determined the benefits of different green manure crops, seeding dates, and termination methods on soil nitrogen, phosphorus, and moisture, as well as the performance of durum wheat following green manures the following year. Field experiments were conducted at Swift Current, Saskatchewan, from 2006 to 2009. Three green manure crops [forage pea (Pisum sativum L.), chickling vetch (Lathyrus sativus L.), and black lentil (Lens culinaris Medik.)] were seeded in May, June, and July, and terminated at full bloom using glyphosate, rototilling or by frost. Other treatments included summerfallow and stubble of selected crops harvested for grain or silage. Different green manure crops, seeding dates or termination methods had similar effects on soil moisture, available N, and exchangeable P at termination or the following spring. These effects of green manure management on soil residual characteristics were comparable to those observed under summerfallow, but higher than those on grain or silage stubble. Therefore, green manure is a viable alternative to summerfallowing and could be seeded any time during the growing season. If seeded late, green manure could be terminated by frost, thus saving on costs.


Plant Disease ◽  
2020 ◽  
Author(s):  
Ruoxi Xia ◽  
Arthur W. Schaafsma ◽  
Felicia Wu ◽  
David C. Hooker

Fusarium head blight (FHB) in wheat causes yield loss, quality reduction, and mycotoxin contamination in temperate wheat production areas worldwide. The objective of this study was to quantify the progress of agronomic and FHB management strategies during the past two decades on FHB suppression and agronomic performance of winter wheat in environments favorable for FHB. Field experiments were conducted in environments typical in FHB epidemics for comparing common agronomic and FHB management practices used in the 1996 era compared to those used in 2016. The experiments included a comparison of 3 different nitrogen fertilizer (N) application rates, 6 old (1996-era) and new (modern-era) winter wheat cultivars representing combinations of susceptibility-eras to FHB, with and without a fungicide applied at flowering (pydiflumetofen + propiconazole). To mimic environments favorable for infection (similar to 1996 in Ontario, Canada), plots were challenged at 50% anthesis with a F. graminearum macroconidia suspension followed by mist irrigation. The modern management strategy of using moderately resistant cultivars, a fungicide applied at flowering, and a high rate of N fertilizer reduced total deoxynivalenol by 67%, reduced Fusarium damaged kernels (FDK) by 49%, reduced FHB Index by 86%, increased grain test weight by 11% and increased grain yield by 31% compared to the standard management practice of seeding highly susceptible (HS) cultivars with no fungicide and a lower rate of fertilizer N recommended in the 1996 era. This study enabled a published economic assessment of the return on investment for the improvements in cultivars, fungicide and N applications since 1996.


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