Living Mulch Systems Research Articles

Abundance and activity of soil organisms in fields of maize grown with a white clover living mulch

The effects of a white clover (Trifolium repens) living mulch on the soil detritus food-web during maize (Zea mays) culture were studied on Andosols for 2 years. In the first year, the use of white clover (W) and Italian ryegrass (I; Lolium multiflorum) was compared against the control treatment in the absence of fertilization. In the second year, combinations of white clover and inorganic fertilizers were studied. Bacterial and fungal substrate-induced respiration and the population densities of protozoa (flagellates, naked amoebae, ciliates), nematodes, and microarthropods (mites, collembolans) increased with the use of white clover living mulch. In the first year, nematode and microarthropod populations increased throughout the growing season in the living mulch plots. In the second year, the communities of soil organisms under the white clover living mulch had reached a more mature successional stage and were characterized by increased populations of organisms in the fungal pathway of organic matter decomposition and by a high population density of higher trophic groups (e.g., mesostigmatid mites and ciliates). The higher litter decomposition rate in the living mulch plots suggested that the function of the detritus food-web was enhanced under the living mulch system. On the other hand, inorganic fertilization only increased populations of nematodes and mesostigmatid mites in mid-summer, possibly owing to better maize growth, and had no effect on other soil organisms.

Tropical Eggplant (Solanum melongena L.) Production with a Buffelgrass (Pennisetum ciliare L.) Living Mulch System in Hawaii

ABSTRACT This research was conducted to determine if a living mulch polyculture system, designed for mitigating non-point source pollution, is also a viable crop-production system in a tropical island ecosystem. Two field experiments were conducted in Hawaii to cornpare the yield of eggplant in a buffelgrass (Pennisetum ciliare L.) living mulch system with the yield of eggplant in a conventional monoculture bareground system. In the first experiment, eggplant grown in chemicalsuppressed living mulch treatment plots produced over 100% higher yields than the conventional treatment plots, due to higher mite (Tetranychus cinnabarinus Boisduval) infestation levels in the conventional monoculture plots. Soil moisture levels were higher within the living mulch treatments than in the conventional treatment. Hand labour times recorded to maintain a weed-free status were significantly greater in the conventional treatment plots due to the greater weed densities established in the exposed between-row spaces. The establishment of a buffelgrass living mulch increased microbivorous nematode populations, but only had a variable influence on plant-parasitic nematode populations. In the second experiment, the conventional monoculture treatment had a significantly higher early yield, but was not significantly higher than the suppressed living mulch treatments in the final cumulative yields. Eggplant yields from the mechanicaland chemicalsuppressed living mulch treatments were significantly higher than in the unmanaged living mulch treatment. This research supports the living mulch system as a viable production system with integrated benefits of pest management and land stewardship for tropical island ecosystems.

Interferências mútuas entre a cultura do milho, espécies forrageiras e plantas daninhas em um sistema de consórcio: III - implicações sobre as plantas daninhas

O objetivo desta pesquisa foi avaliar as conseqüências da adoção de um sistema de consórcio com culturas forrageiras sobre a infestação e a produção de massa seca e área foliar de três espécies daninhas, na cultura do milho. Os tratamentos resultaram da combinação entre quatro níveis do fator plantas forrageiras (Brachiaria decumbens, Brachiaria brizantha, Panicum maximum e ausência de forrageira) e três níveis do fator plantas daninhas (Ipomoea grandifolia corda-de-viola, Amaranthus hybridus caruru-roxo e Digitaria horizontalis capim-colchão). Durante a condução do experimento foram avaliadas a área foliar, a massa seca e a densidade das plantas daninhas quando submetidas à convivência com a associação do milho e espécies forrageiras. De forma geral, o sistema de produção que envolve a associação de uma cultura forrageira com a cultura do milho reduz a infestação e suprime o crescimento de plantas daninhas no sistema; B. decumbens foi a forrageira que menos reduziu a infestação de plantas daninhas; a espécie B. brizantha foi a forrageira mais eficiente em reduzir a infestação de corda-de-viola, mas não suprimiu o crescimento do caruru-roxo; e a forrageira P. maximum foi a espécie que mais reduziu o crescimento do caruru-roxo e a área foliar do capim-colchão.

Eggplant (Solanum melongena L.) Yield Comparisons of Managed Buffelgrass (Pennisetum ciliare L.) Living Mulch Systems to a Conventional Monoculture Bare Ground System in Hawaii

Two long-term field experiments were conducted from 1998 to 2000 to compare the yields of marketable eggplant in a buffelgrass living mulch system to a conventional monoculture bare ground system. The initial experiment compared the yields in the conventional treatment to living mulch treatments, that were chemically suppressed at three levels of sethoxydim applied at 0.1, 0.2, and 0.3 kg·ha-1 a.i. Regression analysis did not reveal a significant linear response of eggplant yield to increasing levels of sethoxydim. The average cumulative yield of the three living mulch treatments, 130 days after transplant (DAT), was 4,296 kg·ha-1 compared to 2,079 kg·ha-1 for the conventional treatment. The higher yield in the living mulch treatments was due to a mite infestation that was much more pronounced in conventional plots. In the follow-up experiment, three different living mulch management (mechanical suppression, chemical suppression, and untreated) treatments were compared to a conventional monoculture bare ground treatment. There was no mite infestation affecting this experiment and cumulative yields of marketable fruit at 159 DAT were 5,362, 4,521, 4,155, and 2,535 kg·ha-1 for conventional bare ground, mechanical suppression, chemical suppression and untreated living mulch treatments, respectively. Orthogonal comparisons showed that the yields from the conventional treatments were not significantly different from the suppressed living mulch treatments. However, the eggplant yields from the unmanaged living mulch treatments were significantly reduced in comparison to the conventional and also the suppressed living mulch treatments.

Interactions of maize and Italian ryegrass in a living mulch system: (1) Shoot growth and rooting patterns

It has been demonstrated that the use of living mulches solves some of the environmental problems associated with the conventional cropping of maize (Zea mays L.). However, plant growth and yield are often reduced in such a cropping system. Since shoot competition between the main crop and the cover crop can be avoided by regular cutting of the cover crop, it was hypothesized that decreases in maize growth and yield in a living Italian ryegrass (Lolium multiflorum Lam.) mulch must be related to below ground interactions between the two species and that these may be traced back to the characteristics of their root systems. Two cropping systems, maize grown alone in bare soil (conventional cropping, BS) or together with a living Italian ryegrass mulch (LM), were studied in lysimeters (1.0 m2 surface area and 1.1 m depth) placed outdoors, near Zurich Switzerland, for a duration of three years. In the LM treatment a strip, 0.3 m wide, in the center of the plot around the maize row was free of grass. For comparison, an Italian ryegrass (RG) treatment, managed as the LM treatment but without maize plants, was also included in the study. Minirhizotrons (54 mm inner diameter) were horizontally installed at ten soil depths between 0.0 and 1.0 m, perpendicular to the orientation of the maize rows. The development of the maize shoot and the rooting patterns were observed non-destructively. LM strongly modified the maize crop by decreasing growth and duration of the leaf area, and thus biomass and grain yield at harvest by as much as 78 and 72%, respectively. Maximum root densities in the three treatments were observed around the time of maize anthesis. However, BS maize was unable to build up root densities similar to those observed in Italian ryegrass plots at the time of maize sowing. The root densities of the LM and the RG treatments were usually similar. The inability of the maize plants to establish a competitive root system in the LM limits the supply of nutrients and water and therefore reduces growth and yield. Improving the productivity of maize in living mulches will depend on the ability to achieve a better separation of the rooting volumes of the two species, so that specific steps to facilitate the main crop and control the living mulch can be taken.

Interactions of maize and Italian ryegrass in a living mulch system: (2) Nitrogen and water dynamics

Water and nitrogen availability may limit the growth of the main crop competing with a cover crop in a living mulch system. Some aspects of the dynamics of water (soil water content and deep percolation) and nitrogen (concentration in soil solution and leachate) were studied in maize (Zea mays L.) sown into a bare soil (BS, conventional cropping) or into a living Italian ryegrass (Lolium multiflorum Lam.) mulch (LM) during three years. Eight lysimeters (1.0 by 1.0 m square surface area and 1.1 m deep) with ceramic suction cups, TDR probes and a drainage pipe were used each. In LM a 0.3 m wide strip was kept free of grass around the maize row. The living mulch reduced the soil water content between 0.3 and 0.9 m soil depth, which remained lower even after intense rainfall. Deep percolation over the entire maize crop season was at least 40% lower in the LM compared to the BS treatment. In LM the nitrate concentrations in the soil solution and in the leachate (usually <10 mg L−1) were very low. In BS the nitrate concentration in the leachate reached as much as 70 mg L−1. Losses of N in LM did not reach 1% of the values observed in BS. Reduced water and N availability in LM contribute to explain the decrease in growth and yield of the maize plants, and are in good agreement with the dense root system developed in this cropping system as compared to BS. The challenge for the development of living mulch systems is to improve the uptake of water and nitrogen by the roots of the main crop in a competitive environment without affecting the capacity of the cover crop to prevent N losses by leaching.

Performance of reduced-tillage cropping systems for sustainable grain production in Maryland

AbstractSustainable production systems are needed to maintain soil resources and reduce environmental contamination on erodible lands that are incompatible with tillage-intensive operations. A long-term cropping systems comparison was established at Beltsville, Maryland, on a site with 2 to 15% slope to evaluate the efficacy of sustainable strategies compatible with reduced-tillage systems. All systems followed a 2-year rotation of corn the first year and winter wheat followed by soybean the second year. Treatments included (1) no-tillage system with recommended fertilizer and herbicide inputs, (2) crownvetch living mulch system with similar inputs to the no-tillage system, (3) cover crop system including a hairy vetch cover crop before corn and a wheat cover crop before soybean with reduced fertilizer and herbicide inputs, and (4) manure system including crimson clover green manure plus cow manure for nutrient sources, chisel plow/disk for incorporating manure, and rotary hoe plus cultivation for weed control. Results from the initial 4 years demonstrated the relative productivity of these systems. Corn yields were similar in the no-tillage and cover crop systems in each year; both systems averaged 7.8 Mg ha-1 compared to 5.7 Mg ha-1 in both the crownvetch and manure systems. Wheat yields were highest in the manure system in the first 2 years and in the crownvetch system in the last 2 years. Soybean yields were highest in the cover crop system in all years. The manure system usually had lower yields than the highest yielding systems, partly because of competition from uncontrolled weeds. Several measures of the efficiency of grain production were evaluated. The no-tillage system produced the most grain per total vegetative biomass throughout the rotation. The cover crop system produced the most grain per unit of external nitrogen input and, along with the no-tillage system, had the highest corn water-use efficiency. The cover crop system also recycled the most vegetative residues and nutrients of all systems. No single system performed best according to all measures of comparison, suggesting that trade-offs will be required when choosing production systems.

COVER CROPS IN SUSTAINABLE FOOD PRODUCTION

Cover crops are important components of sustainable agricultural systems. They increase surface residue and aid in the reduction of soil erosion. They improve the structure and water-holding capacity of the soil and thus increase the effectiveness of applied N fertilizer. Legume cover crops such as hairy vetch and crimson clover fix nitrogen and contribute to the nitrogen requirements of subsequent crops. Cover crops can also suppress weeds, provide suitable habitat for beneficial predator insects, and act as non-host crops for nematodes and other pests in crop rotations. This paper reviews the agronomic and economic literature on using cover crops in sustainable food production and reports on past and present research on cover crops and sustainable agriculture at the Beltsville Agricultural Research Center, Maryland. Previous studies suggested that the profitability of cover crops is primarily the result of enhanced crop yields rather than reduced input costs. The experiments at the Beltsville Agricultural Research Center on fresh-market tomato production showed that tomatoes grown with hairy vetch mulch were higher yielding and more profitable than those grown with black polyethylene and no mulch system. Previous studies of cover crops in grain production indicated that legume cover crops such as hairy vetch and crimson clover are more profitable than grass cover crops such as rye or wheat because of the ability of legumes to contribute N to the following crop. A comparative analysis of four reduced-tillage corn based cropping systems at the Sustainable Agricultural Demonstration site showed that the cover crop system with corn following hairy vetch produced the largest average gross margin, followed by the conventional no-tillage system, a manure-based system, and a crown vetch living mulch system. The EPIC model to simulate the long-term economic and environmental impacts of incorporating cover crops into grain production systems in mid-Atlantic states was used. Results based on 60 simulation years indicated that there are tradeoffs between the competing objectives of increased profitability, lower soil erosion, and reduced nutrient and pesticide hazards to surface and groundwater supplies. A corn/soybean two-year rotation was found to be the most profitable, while the cover crop system and the manure system were found to be the most environmentally sound.

Living Mulches For Organic Farming Systems

An important aspect of organic farming is to minimize the detrimental impact of human intervention to the surrounding environment by adopting a natural protocol in system management. Traditionally, organic farming has focused on the elimination of synthetic fertilizers and pesticides and a reliance on biological cycles that contribute to improving soil health in terms of fertility and pest management. Organic production systems are ecologically and economically sustainable when practices designed to build soil organic matter, fertility, and structure also mitigate soil erosion and nutrient runoff. We found no research conducted under traditional organic farming conditions, comparing bareground monoculture systems to systems incorporating the use of living mulches. We will be focusing on living mulch studies conducted under conventional methodology that can be extrapolated to beneficial uses in an organic system. This article discusses how organic farmers can use living mulches to reduce erosion, runoff, and leaching and also demonstrate the potential of living mulch systems as comprehensive integrated pest management plans that allow for an overall reduction in pesticide applications. The pesticide reducing potential of the living mulch system is examined to gain insight on application within organic agriculture.

Maize production in a grass mulch system – seasonal patterns of indicators of the nitrogen status of maize

In hilly regions with high precipitation, planting maize ( Zea mays L.) into living mulches of winter cover crops may alleviate some of the problems (erosion, runoff of agrochemicals, nitrate leaching) associated with conventional maize cropping. Nitrogen was found to be more yield-limiting for maize planted into a grass sod than for traditionally grown maize. The aim of the present study was to follow the seasonal patterns of some indicators of the N status (whole-shoot concentrations of N and nitrate as well as leaf greenness, as measured by the SPAD 502 chlorophyll meter) of silage maize in three cropping systems. The experiments were conducted in the midlands of Switzerland, where annual precipitation is high (≥1000 mm), for 3 years. The cropping systems were PLOUGH (maize sown into the bare autumn-ploughed soil), GRASS/HERB (maize planted into a living, subsequently herbicidally killed Italian ryegrass [ Lolium multiflorum Lam.] sod), and GRASS/MECH (similar to GRASS/HERB, but the growth of the ryegrass sod was mechanically regulated). Planting was done with a strip tillage seeder. There were two N treatments: 110 and 250 kg N/ha (inclusive of the mineral N content of the soil from 0 to 90 cm depth). With 110 kg N/ha, the following differences between the cultural systems were found: (i) as early as the 3rd leaf stage, PLOUGH maize exhibited higher whole-shoot concentrations of nitrate than sod-planted maize; (ii) between the 3rd and 6th leaf stages, chlorophyll meter measurements revealed that the uppermost unfolded leaves of PLOUGH maize were markedly greener than those of maize on the mulch seeding plots; (iii) from the 6th leaf stage onwards, PLOUGH maize showed a higher N concentration than did maize grown in grass swards. Under 250 kg N/ha, the differences between the cultivation methods were much less pronounced. It is concluded that efforts to optimize the environmentally friendly living mulch systems should focus on reducing the competition between maize and the cover crop for N.

The Impact of Living and Cover Crop Mulch Systems on Pests and Yields of Snap Beans and Cabbage

ABSTRACT Living or cover crop mulches may reduce pesticide and fertilizer use while protecting the soil. Three systems in cabbage [hairy vetch cover crop mulch (HV), cereal rye cover crop mulch (CR), and a perennial ryegrass living mulch (PR)] or two systems in snap beans (CR and PR) were compared to conventional fall-tillage with trifluralin (CT). The CR with fall-planted rye was best for suppressing weeds. None of the mulches adequately suppressed cabbage insect pests. In 1992, hairy vetch regrowth reduced cabbage growth and yield. Snap bean yields were reduced in the CR system. The mulches are more management intensive and variable than the CT. CR was the most promising mulch, but further research is needed to develop approaches that prevent snap bean yield loss.

Establishment of Asparagus with Living Mulch

Experiments were begun in 1990 to determine the efficacy of using grassy and leguminous living mulches for asparagus (Asparagus officinalis L.) establishment and production. Ten-week-old seedlings of hybrid asparagus, cv. Syn4-56 were planted in loamy sand in the irrigated Central Sands of Wisconsin. Treatments were unsuppressed living mulches of perennial ryegrass (Lolium perenne L.), Dutch white clover (Trifolium repens L.), a mixture of ryegrass and clover, and a cultivated no-mulch control. A second variable, ammonium nitrate, banded at 40 and 80 lb N/acre, with a control of 0 lb N/acre, was factorially combined with mulch treatments. Asparagus fern growth with living mulches in year 1 was half that of asparagus grown with no mulch. Asparagus fern growth with clover and mixed mulches in year 2 averaged 75% of that grown without mulch. Fern growth with ryegrass mulch in year 2 was 50% of that grown with no mulch. Asparagus N uptake in clover and mixed mulch plots was as great as that grown with no mulch at each level of applied N. Weeds were controlled better by clover and mixed mulches than by ryegrass mulch or by cultivation in the no-mulch plots

214 LIVING-MULCH AND GENOTYPE EFFECT ON THE PRODUCTIVITY AND GROWTH OF EGGPLANT

Living mulches offer a low-input alternative to achieve weed control while minimizing herbicide applications, decreased fertilizer leaching, insect and nematode management. and improved soil texture. A study was conducted to evaluate the effect of a Rhodes Grass (Chloris gayana cv. Katambora) living mulch on the growth and productivity of ten eggplant. Solanum melongena, cultivars grown under fertigation. The living sod was established at the Univ. Hawaii Waimanalo Experiment Station in June 1992. Soil analysis was taken before experiment initiation. Ten eggplant cultivars were transplanted on both living-mulch and control (woven-polyethelene mulch) plots on 4 March 1993. Weekly or bi-weekly harvests were conducted for six months. beginning on 19 May 1993. In addition plant height and canopy dimensions were determined on 16 April. and 10 Nov. Plant growth was monitored throughout the experiment. Soil samples were taken from the eggplant rhizosphere, hare-ground and in Rhodes grass monoculture, for nematode count determinations. Soil samples were also taken for nutrient determination after completion of the experiment. Overall yields were greater in the polyethelene mulch than in the living mulch plots. A differential response was observed on the response of cultivars to cropping system. However the most vigorous cultivars performed well in both systems. The living mulch system showed potential for nematode management in eggplant agroecosystems.

Managing interference in a sweet corn-white clover living mulch system

AbstractLiving mulches are vegetative covers that can be grown in association with row crops to reduce soil erosion, improve trafficability and suppress weeds. Interference by the living mulch can reduce yields of an associated crop. The interference between a white clover (Trifolium repensL. ‘New Zealand’) living mulch and sweet corn (Zea maysL. ‘Golden Jubilee’) was studied using an established clover sward that was mowed and then sprayed with 1 to 1.5 kg ai/ha of atrazine. Corn was planted at different densities and planting arrangements into a narrow band tilled in the clover. Interference by clover reduced corn yields by 12 to 39%. However, when corn row width was reduced from 0.76 to 0.38 m, competition among corn plants declined; they became more vigorous and clover- suppress ive and reached even higher yields than conventional (no mulch) corn in 0.76 m rows. Similarly, sweet corn planted at a range of densities into a clover mulch killed by atrazine yielded more in equidistant planting than in wide (0.76 m) rows. A near equidistant corn planting arrangement can be a low-input alternative to achieve season-long clover suppression and thus minimize clover's competition with the intercropped corn.

RYEGRASS AND CLOVER AS LIVING MULCHES FOR SWEET CORN ON SANDY SOIL

Two living mulches were studied for their effect on weed control and nitrogen cycling in sweet corn grown on sandy soil under sprinkler irrigation. Plots with either annual ryegrass (Lolium perenne) or dwarf white clover (Trifolium repens) planted between sweet corn rows were compared to plots kept weed free by cultivation or herbicides. Each sweet corn plot (18.3m × 3.7m) was split into two subplots according to level of applied nitrogen. One subplot received 112 kg N/ha (100 #/A) and the other 224 kg N/ha (200#/A). Nitrate and ammonium levels were measured in soil samples and nitrogen levels were measured in plant tissue samples. Measurements such as corn height were taken, as well as percent mulch cover, plant tissue fresh weight and dry weight, total corn yield and marketable yield, and weed counts. Applied nitrogen leached through the soil profile more rapidly than expected (within 2 weeks) and sweet corn growth and yield were poor in all the low level nitrogen plots. Even at the high nitrogen level, sweet corn yield was limited by mulch growth. The weed control benefits of this living mulch system could potentially be realized if mulch competition were limited, especially during early growth stages of the corn.

Reseeding of Crimson Clover and Corn Grain Yield in a Living Mulch System

A major drawback to the use of crimson clover Trifolium incarnatum L.) as a winter legume cover with corn (Zea mays L.) is the cost of new seed each fall. Planting corn into a living mulch and allowing the clover to reseed could reduce these costs. This study was conducted for 3 yr (1989–1990) at Plains and Griffin, GA, to determine the feasibility of planting corn into various widths of chemically killed strips of crimson clover and allowing a living clover mulch between corn rows to mature and reseed naturally. Each fall, ‘Tihbee’ crimson clover was planted on a new strip and the previous year's plots were continued for reseeding studies in 1989 and 1990. Treatment included chemically killing 0, 25, 60, 80, 95, and 100% of the total area with paraquat (1.1-dimethyl-4,4″-bipyridinium ion) Killing the clover was accomplished 2 week before or at corn planting, except the 25% kill, which was killed at planting only. ‘Pioneer 3165’ corn was no-till planted on all of the plots in late March to early April at Plains and in mid April to early May at Griffin. Reseeding was satisfactory (>70% groundcover) for killed strips of 80% or less. Corn grain yields when clover was completely killed were 6 to 10 Mg ha⁻¹ at Griffin and 3 to 6 Mg ha⁻¹ at Plains, where rainfall was less. Corn grain yield was not depressed by the presence of a living clover mulch, as long as the clover was killed in strips of 60% or greater, compared with the conventional practice of completely killing clover. Time of killing clover was not important in most instances, but in 1989 killing early significantly reduced corn grain yields in the reseeded plots at Griffin and, to a lesser extent, in the fall-seeded plots at Plains. Based on corn yield and reseeding of clover, planting corn into clover killed in strips of 60 to 80% appears to be the optimum.

Corn Growth and Yield in an Alfalfa Living Mulch System

Reduced or no tillage living mulch systems for corn (Zea mays L.) production after alfalfa (Medicago sativa L.) have the potential to reduce soil erosion and water pollution. Available soil water may be the most limiting factor in use of living mulch systems in the north central states. Our objective was to compare growth and yield of corn seeded no-till into chemically suppressed and unsusuppressed alfalfa sods to corn seeded using a conventional till system (alfalfa moldboard plowed) with and without irrigation. Alfalfa suppression treatments were : (i) no suppression ; (ii) partial suppression achieved by chemically killing alfalfa in 15-in. bands over the corn row using atrazine ; (iii) partial suppression achieved by a broadcast application of atrazine (...2)

Carry on smoking?

Corn (<i>Zea mays</i>) grown in the southern Piedmont requires 200 to 280 kg nitrogen (N) ha⁻¹ annually and requires up to 0.87 cm of water per day, making groundwater systems susceptible to nitrate (NO₃⁻) leaching. A perennial white clover (<i>Trifolium repens</i> L.) living mulch (LM) system may reduce NO₃-N leaching by using legume N to replace mineral N, though little information is available on such a system in the southern Piedmont. Therefore, a HYDRUS-1D model was used to simulate water and NO₃-N flux in three cover crop systems. Cereal rye (<i>Secale cereal</i> L.) (CR), crimson clover (<i>Trifolium incarnatum</i> L.) (CC), and a white clover LM were fertilized with 280, 168, and 56 kg N ha⁻¹. The HYDRUS-1D model was calibrated and validated with observed water contents and NO₃-N data that were collected over two years. Water and NO₃-N flux models were created for each treatment and evaluated using coefficient of determination, percentage bias, and index of agreement, and showed good agreement to observed data. Nitrate leaching below 1 m in 2015/2016 was 23.5, 12.7, and 21.4 kg ha⁻¹ for the CC, LM, and CR treatments, respectively, but was less than 1 kg ha⁻¹ for all treatments in 2016/2017 due to prolonged drought. Differences in leached NO₃-N among treatments were attributed to variation in mineral N application rate and NO₃-N uptake by cover crops. Overall, results suggest that the use of a perennial LM system may reduce NO₃-N leaching when compared to annual CC and CR cover crop systems.