CONV Systems Research Articles

Synergy between compost and cover crops in a Mediterranean row crop system leads to increased subsoil carbon storage

Abstract. Subsoil carbon (C) stocks are a prime target for efforts to increase soil C storage for climate change mitigation. However, subsoil C dynamics are not well understood, especially in soils under long-term intensive agricultural management. We compared subsoil C storage and soil organic matter (SOM) composition in tomato–corn rotations after 25 years of differing C and nutrient management in the California Central Valley: CONV (mineral fertilizer), CONV+WCC (mineral fertilizer and cover crops), and ORG (composted poultry manure and cover crops). The cover crop mix used in these systems is a mix of oat (Avena sativa L.), faba bean (Vicia faba L.), and hairy vetch (Vicia villosa Roth). Our results showed a ∼19 Mg ha−1 increase in soil organic C (SOC) stocks down to 1 m under ORG systems, no significant SOC increases under CONV+WCC or CONV systems, and an increased abundance of carboxyl-rich C in the subsoil (60–100 cm) horizons of ORG and CONV+WCC systems. Our results show the potential for increased subsoil C storage with compost and cover crop amendments in tilled agricultural systems and identify potential pathways for increasing C transport and storage in subsoil layers.

Weed competition in organic and no-till conventional soils under nonlimiting nutrient conditions

AbstractSome well-managed organic soils are known to have higher crop yield potential than conventionally managed soils due to the greater soil quality and the ability to tolerate weed competition. However, low available soil mineral N and P in some organic systems may mask such soil quality–related benefits. We hypothesize that when plant-available N and P are not limiting, tillage-based highly diverse organic crop rotations have less yield loss (better crop tolerance) due to weed competition and higher crop yields than no-till conventional systems with low-diversity rotations. A greenhouse study was carried out in Saskatoon, Canada, using long-term (18-yr) organically managed soils (ORG) and no-till conventional soils (CONV) with three crop rotation diversities (LOW, MEDIUM, and HIGH) to compare the crop tolerance to weed competition under standard soil nutrient management conditions and under excess supply of mineral N and P. Under fertilized conditions, crop biomass increased by 50% and 69% in ORG and CONV systems, respectively. Weed biomass was similar between ORG and CONV systems under nonfertilized conditions but was 14% greater in CONV when excessive N and P were supplied. Crop biomass loss (crop tolerance) was not different among cropping systems under excess fertilizer or under standard fertilizer levels. Even with greater weed biomass under fertilized conditions, the CONV system showed crop tolerance similar to that of the ORG system. Under nonfertilized conditions, the crop biomass yield was 43% lower in ORG compared with CONV, and even after mineral N and P were applied, ORG systems showed less (17%) crop biomass than CONV. Further, differences in crop tolerance were not identified among crop rotations under both fertilizer levels. Overall, this study revealed that there were no yield benefits or better crop tolerance to weed competition in organically managed soils compared with no-till conventional soils, even under nonlimiting soil macronutrient conditions.

Forage systems and sustainability of milk production: Feed efficiency, environmental impacts and soil carbon stocks

Farm sustainable intensification is an important strategy to reduce environmental impacts, which can be obtained in particular through improvements in the milk production per cow and feed efficiency, as well as by increasing the net primary production of the Utilized Agricultural Area. Farming systems that are mainly based on multi-annual/perennial forages may increase soil carbon (C) sequestration, which is a significant greenhouse gases mitigation strategy. The aim of the present study has been to identify the forage systems related to dairy farms that are able to maximize feed production and to improve feed efficiency and C sequestration, in order to achieve the best environmental sustainability result. A group of 46 dairy farms was selected to represent the most widespread forage systems in Northern Italy. The identified forage systems were: CONV, conventional corn silage system; MIXED, low intensity mixed system; HQFS, high quality forage system; WICE, winter cereal silage system; PR DRY, hay system for Parmigiano Reggiano PDO cheese production and PR-FRESH, hay and fresh forage system for Parmigiano Reggiano PDO cheese production.Primary data were collected to carry out a life cycle assessment. Soil samples of representative crops of the forage systems were collected to determine in particular the soil organic carbon density and soil organic matter. The WICE, CONV and HQFS forage systems provided the greatest amount of dry matter (DM) per hectare, whereas the PR FRESH system showed the highest soil C density. The LCA results showed that the HQFS system registered the lowest values for all the impact categories (except for land occupation and the use of non-renewable resources), probably due to the higher milk production, both in terms of individual production (fat and protein corrected milk/head) and feed efficiency (kg milk/kg DMI). More intensive systems, such as HQFS, demonstrated that the milk production per cow and feed efficiency are negatively related to the impact per kilogram of product. The HQFS system also resulted to be more sustainable, in terms of feed self-sufficiency, as a high amount of DM per hectare. However, as far as this forage system is concerned, there is still room to strengthen environmental sustainability, since HQFS also showed the lowest C soil density. Further investigations are needed to consider environmental sustainability over a wider spectrum.

The productivity of two yellow lupine (Lupinus luteus L.) cultivars as an effect of different farming systems

Between 2011 and 2015, a two-factor field experiment on yellow lupine was conducted in Gorzyń, Poland (52°34'07''N, 15°54'33''E). The first-order factor was the farming technology: low-input (LI; without fertilization and chemical protection); medium-input (MI; medium level of fertilization and chemical protection) and high-input (CONV; high level of fertilization and chemical protection). The second-order factor was the cultivar (indeterminate cv. Mister and determinate cv. Perkoz). The research assessed the productive and economic effects of two yellow lupine cultivars grown in different farming systems. The weather conditions significantly influenced the yield in consecutive years of the research. A change from the LI farming system to the MI and CONV systems increased the seed yield by 13.1% and 22.0%, respectively. The research also showed differences in the yield of the cultivars under study. The indeterminate cv. Mister yielded more seeds than the determinate cv. Perkoz (1.95 t/ha vs 1.81 t/ha). The research also showed that when the EU subsidies were added, the value of production increased along with the cultivation intensity. However, an increase in the outlay on industrial means of production in higher-intensity technologies caused a decrease in the gross agricultural income value.

Impact of "Raised without Antibiotics" Beef Cattle Production Practices on Occurrences of Antimicrobial Resistance.

The specific antimicrobial resistance (AMR) decreases that can be expected from reducing antimicrobial (AM) use in U.S. beef production have not been defined. To address this data gap, feces were recovered from 36 lots of "raised without antibiotics" (RWA) and 36 lots of "conventional" (CONV) beef cattle. Samples (n = 719) were collected during harvest and distributed over a year. AMR was assessed by (i) the culture of six AM-resistant bacteria (ARB), (ii) quantitative PCR (qPCR) for 10 AMR genes (ARGs), (iii) a qPCR array of 84 ARGs, and (iv) metagenomic sequencing. Generally, AMR levels were similar, but some were higher in CONV beef cattle. The prevalence of third-generation cephalosporin-resistant (3GCr) Escherichia coli was marginally different between production systems (CONV, 47.5%; RWA, 34.8%; P = 0.04), but the seasonal effect (summer, 92.8%; winter, 48.3%; P < 0.01) was greater. Erythromycin-resistant (ERYr) Enterococcus sp. concentrations significantly differed between production systems (CONV, 1.91 log10 CFU/g; RWA, 0.73 log10 CFU/g; P < 0.01). Levels of aadA1, ant(6)-I, bla ACI, erm(A), erm(B), erm(C), erm(F), erm(Q), tet(A), tet(B), tet(M), and tet(X) ARGs were higher (P < 0.05) in the CONV system. Aggregate abundances of all 43 ARGs detected by metagenomic sequencing and the aggregate abundances of ARGs in the aminoglycoside, β-lactam, macrolide-lincosamide-streptogramin B (MLS), and tetracycline AM classes did not differ (log2 fold change < 1.0) between CONV and RWA systems. These results suggest that further reductions of AM use in U.S. beef cattle production may not yield significant AMR reductions beyond MLS and tetracycline resistance.IMPORTANCE The majority of antimicrobial (AM) use in the United States is for food-animal production, leading to concerns that typical AM use patterns during "conventional" (CONV) beef cattle production in the United States contribute broadly to antimicrobial resistance (AMR) occurrence. In the present study, levels of AMR were generally similar between CONV and "raised without antibiotics" (RWA) cattle. Only a limited number of modest AMR increases was observed in CONV cattle, primarily involving macrolide-lincosamide-streptogramin B (MLS) and tetracycline resistance. Macrolides (tylosin) and tetracyclines (chlortetracycline) are administered in-feed for relatively long durations to reduce liver abscesses. To ensure judicious AM use, the animal health, economic, and AMR impacts of shorter duration in-feed administration of these AMs should be examined. However, given the modest AMR reductions observed, further reductions of AM use in U.S. beef cattle production may not yield significant AMR reductions beyond MLS and tetracycline resistance.

Nutritional quality of lettuce and onion as companion plants from organic and conventional production in north Greece

The purpose of this study was to examine the effect of production systems – (organic-ORG or conventional-CONV) and growing season (autumn or spring) of cos lettuce (Lactuca sativa L. var. longifoila cv. ‘Parris Island’) and green onion (Allium cepa cv. ‘Sturon’) as companion planting (the onions and lettuce were grown in the same plot of land), on the yield and quality parameters (mineral composition, phenolic profiles, antioxidant capacity, nitrate content). Soil and meteorological parameters were measured. Lettuce plant in both production system obtained higher content of K, B, Zn, or Fe compared to onion. The general order of the mineral content in both plants was K>Ca>Mg>Fe>Mn>B>Zn>Cu. Organically grown green onions from both growing seasons had higher contents of all macro and micro elements (except Cu) compared to the conventionally grown onions. Lettuce from CONV systems contained more Ca, Mg, Mn, Fe, Cu than that from ORG production. However, no significant difference in total phenols content (TPC) was observed between production system and growing season in lettuce. TPC in green onion was higher compared to lettuce. A similar trend was observed for total antioxidant capacity. The nitrate concentration was significantly higher in lettuce than in onion. Lettuce and onions grown in the fall-winter period contained higher nitrate levels compared to lettuce and onions grown in spring-summer. In conclusion, companion planting can result in an increase in productivity of vegetables per unit area, and can improve net income. At present however, we cannot conclusively demonstrate a higher health-promoting value of ORG lettuce and onion in comparison to lettuce and onion grown by CONV farming methods.

Effects of groundcover management on soil properties, tree physiology, foliar chemistry and growth in a newly established Fraser fir (Abies fraseri [Pursh] Poir) plantation in Michigan, United States of America

Incorporating cover crops into Christmas tree plantations may potentially improve soil fertility, tree growth and quality and be an alternative to commercial nitrogen (N) fertilizers. However, cover crops may compete with the trees for water and other nutrients than N. This study was carried out to assess whether soil fertility, tree survival and growth could be improved by incorporating leguminous and non-leguminous cover crops into the Fraser fir (Abies fraseri) production system. Dutch white clover (Trifolium pratense), alfalfa (Medicago sativa) and perennial ryegrass (Lolium perenne) were grown in a newly established Fraser fir plantation using two cover crop management practices; no banding (NB) by growing each cover crop throughout the entire plot and banding (B) by creating a 61 cm-wide bare zone centered on the tree rows. A conventionally-managed system (CONV) was used as a control. The cover crop aboveground biomass and N content were assessed. Soil available N (NO3− and NH4+) and N mineralization were measured at 0–15, 15–30 and 30–45 cm soil depths. Tree survival, growth, photochemical efficiency of photosystem II (Fv/Fm), branch water potential (Ψw) and foliar nutrients were also evaluated. Biomass production was as high as 13.9, 10.2 and 5.9 Mg DM ha−1 year−1 for clover, alfalfa and ryegrass, respectively. Cover cropping increased soil available N by 1.5- and 2.2-fold relative the CONV in the top soil layer in 2007 and 2008, respectively. Tree seedling survival and growth in the B and CONV systems were similar. In contrast, NB treatments resulted in poor seedling survival and growth relative to the B and CONV plots. Plant Ψw and Fv/Fm decreased significantly for A. fraseri seedlings on the NB treatments relative to their counterparts on the B and CONV plots. However, cover cropping had marginal effects on foliar nutrients. Cover cropping with banding can be an efficient strategy for maintaining productivity in Fraser fir Christmas plantations.

Soil carbon dioxide emission and carbon content as affected by conventional and organic cropping systems in Mediterranean environment

Carbon sequestration in soil is an important means for reducing net emissions of CO 2 into the atmosphere. We hypothesized that organic cropping systems (ORG) would reduce soil CO 2 emission and increase C storage compared to conventional cropping systems (CONV). The objectives of this study were to: (i) analyze the ORG and CONV systems in terms of soil CO 2 emission and soil C balance and (ii) establish if the soil in the ORG and CONV systems represents a source or a sink of C. A 3-year crop rotation (durum wheat – Triticum durum Desf., tomato – Licopersicum esculentum Mill., and pea – Pisum sativum L.) was carried out in both cropping systems, but the crop rotation was implemented with common vetch ( Vicia sativa L.) before tomato planting and sorghum ( Sorghum bicolor (L.) Moench.) before pea sowing and both green manured only in the ORG system. It was found that the soil CO 2 emission rate at peak times (in spring or at the end of summer – beginning of autumn) in the ORG system was higher than the CONV system. The peak of CO 2 was attributed to the fact that at this time the soil temperature and the relative soil water content (RWC) were probably in the optimal range for soil respiration (17.2 °C and 36.4% of RWC) and the difference between ORG and CONV was probably due to the green manuring of the cover crops in the ORG system. However, even if the cropping systems had a temporary impact on the rate of soil CO 2 emissions, the soil C output calculated as the average of cumulative CO 2 emission over the 3-year period did not show significant differences between the ORG and CONV systems (8.98 Mg C–CO 2 ha −1 vs. 8.06 Mg C–CO 2 ha −1). On the other hand, the C input in the ORG system was higher than in the CONV (9.46 Mg C ha −1 vs. 5.57 Mg C ha −1) as well as the C input/output ratio (1.10 vs. 0.72). The 3-year average of TOC content and C stock were higher in the ORG than in the CONV system (1.24% vs. 1.10% and 27.4 Mg C ha −1 vs. 23.9 Mg C ha −1, respectively). However, the decrease of TOC and C stock over 3 years period suggested that further studies over a longer period are needed to verify if C limitation for soil microbial growth and nitrogen limitation for crop growth in the organic system could hinder soil C accumulation over a longer period.

Weed seedbank and community shifts in a long-term cropping systems experiment

Abstract Characterizing the long-term effect of agricultural management systems on weed communities will aid in developing sustainable weed management practices. Weed seedbanks and aboveground biomass were measured within a corn–soybean–wheat crop sequence from 1990 through 2002 at Hickory Corners, MI. Four management systems were compared: conventional (CONV; full rates of N fertilizer and herbicides, moldboard tillage), no till (NT; same as CONV with no primary tillage), reduced input (RI; reduced rates of N fertilizer and herbicides, moldboard tillage, mechanical weed control, wheat underseeded with red clover), and organic (ORG; same as RI but no synthetic inputs). Multivariate ordinations of weed seedbanks showed a divergence of the CONV and NT systems from the RI and ORG systems. The CONV and NT seedbanks were dominated by grass species (mainly fall panicum and large crabgrass), whereas the RI and ORG systems were dominated by common lambsquarters and common chickweed. Within a single growing season...

910 PB 150 PLANT GROWTH, YIELD, AND WEED CONTROL IN FOUR STRAWBERRY PRODUCTION SYSTEMS

Field plots of four production systems of `Tristar' dayneutral and `Earliglow' Junebearing strawberry (Fragaria xananassa Duch.) were established in 1993. Productions systems included conventional practices (CONV), best-management practices including integrated crop management (ICM), organic practices using corn gluten meal, a natural weed control product, (ORG-CGM), and organic practices using a natural turkey manure product (ORG-TM). `Earliglow' plants grown with ORG-CGM showed the highest number of runners and total vegetative biomass. Plots with CONV and ICM systems using standard herbicide treatments had lower total weed numbers (11 and 18, respectively) than ORG-CGM (63) and ORG-TM (58). `Tristar' plant growth, yield and berry number were reduced when plants were grown under straw mulch in ORG-CGM and ORG-TM compared to CONV and ICM plots with polyethylene mulch.