No-till Fields Research Articles

An in situ method for quantifying tillage effects on soil structure using multistripe laser triangulation

Soil structure is an important physical property that can be degraded by soil tillage, but methods for quantifying soil structure are both few and time consuming. We developed a method for multistripe laser triangulation (MLT) scanning to quantify soil structure that can be accomplished quickly (15 min of scanning per A horizon exposure) in the field. We scanned three soil pits to a depth of 30 cm in three fields under conventional tillage (CT), three under no-till (NT) and three under perennial grass (PG). For both 0- to 10- and 0- to 30-cm pit depths, we calculated the Dirichlet tessellation area variability (DTAV) for each pit. We found the DTAV from 0- to 10-cm depths was sensitive to tillage type (p = 0.09) and clay percentage (p = 0.06), while the 0- to 30-cm depths were sensitive to neither. Specifically, CT fields had significantly higher 0- to 10-cm DTAVs than NT (p = 0.06) and PG (p = 0.07) fields, while NT and PG were not different from one another (p = 0.99). The information carried by the DTAV may be thought of as the regularity of the Dirichlet tessellation feature areas, which is driven by the regularity of observable soil structural units in the field. The DTAV was not significantly related to soil structure type, grade, or class size described in the field. The DTAV provides an alternative or complement to field soil descriptions that is quick, repeatable, objective, and sensitive to changes in soil structure in response to tillage practice.

Sources and subsurface transport of dissolved reactive phosphorus in a semiarid, no-till catchment with complex topography.

The subsurface transport of dissolved reactive phosphorus (DRP) from artificially drained agricultural fields can impair water quality, especially in no-till fields. The distribution of soil P in the wheat (Triticum aestivum L.)-dominated Palouse region in the inland U.S. Pacific Northwest varies greatly due to its steep and complex topography, and a legacy (∼130 yr) of excessive soil erosion and deposition processes. The primary goal of this research was to better understand the magnitude and temporal dynamics of DRP export from an artificial drain line and the variability of subsurface DRP leaching within a long-term, no-till field. Dissolved reactive P in drain line effluent was monitored across three water years. Large intact soil cores were extracted at contrasting field locations (toe and top slope positions) to measure DRP leachate concentration and relative P sorption. Drain line DRP concentration was predominantly >0.05mg L-1 and often exceeded 0.1mg L-1 during winter and early spring. Mean leachate DRP levels were significantly higher in toe slope cores than in top slope cores (0.11 and 0.02mg L-1 , respectively). Saturated hydraulic conductivity varied widely across cores and was not correlated with leachate DRP concentration. All soil cores exhibited high P sorption potential, even under conditions of preferential flow. These findings suggest that much of the DRP transport in these landscapes is derived from P hotspots located in toe slope positions. Application of soil P fertilizer amounts in variable rates that account for spatial variability in P transport may minimize P enrichment and subsequent leaching in these locations.

Special Issue No. – 10, June, 2020 Journal > Special Issue > Special Issue No. – 10, June, 2020 > Page 5 “Quantative Methods in Modern Science” organized by Academic Paper Ltd, Russia MORPHOLOGICAL AND ANATOMICAL FEATURES OF THE GENUS GAGEA SALISB., GROWING IN THE EAST KAZAKHSTAN REGION Authors: Zhamal T. Igissinova,Almash A. Kitapbayeva,Anargul S. Sharipkhanova,Alexander L. Vorobyev,Svetlana F. Kolosova,Zhanat

Special Issue No. – 10, June, 2020 Journal > Special Issue > Special Issue No. – 10, June, 2020 > Page 5 “Quantative Methods in Modern Science” organized by Academic Paper Ltd, Russia MORPHOLOGICAL AND ANATOMICAL FEATURES OF THE GENUS GAGEA SALISB., GROWING IN THE EAST KAZAKHSTAN REGION Authors: Zhamal T. Igissinova,Almash A. Kitapbayeva,Anargul S. Sharipkhanova,Alexander L. Vorobyev,Svetlana F. Kolosova,Zhanat

Physiological Response and Multi-Elemental Content in Lichens Growing on Agricultural Fences: A Pilot Study Comparing No-Tillage and Organic Cropping.

The objective of this study is to compare the physiological response (content and degradation of photosynthetic pigments, membrane oxidation products and soluble proteins) and multi-element content of Ramalina celastri (lichenized fungi) growing on agricultural fences with no-tillage (associated with transgenic crops and agrochemical application), organic cropping and a non-cultivated area. We found that R. celastri did not differ in its physiological response to agricultural practices, except for the contents of chlorophyll b and phaeophytin a which were high in both cultivated areas. Lichens growing in organic cropping fields have higher arsenic, chromium, uranium and internal transition elements common in the earth's crust, possibly due to the greater resuspension of the material during soil tillage. Lichens that grow on posts close to no-tillage field had higher bromine contents (present in numerous pesticides). We found evidence that R. celastri behaves as a tolerant species to air pollution in agricultural environments.

First versus last born: Flowers, pods, and yield formation in no‐tillage lentil

AbstractLentil (Lens culinaris Medik.) is a grain legume crop grown under no‐tillage (NT) management and rhizobia inoculation in the northern Great Plains. Our goal was to characterize pod growth characteristics to understand yield formation in North American short‐season cultivars. Objectives were to compare pods on nodes during early and late reproductive growth through flower and pod number, pod setting percentage, pod growth rate, effective pod‐filling period, and final pod size, and to test if N fertility could increase pod numbers and pod growth under NT management. Two field experiments, Study 1 and Study 2, were conducted at Saskatoon and Indian Head, SK, in western Canada. For Study 1, cultivar CDC Sedley was treated with 0–60 kg N ha−1 on long‐term NT fields for 3 yr (2006–2008). For Study 2, eight cultivars from three maturity classes were grown under control, inoculant, and N fertilizer regimes under NT at Saskatoon (2006 and 2007). Lentil set more yield in early‐flowering nodes via flower number, with 2.6 flowers node−1. Late nodes had fewer (2.1) flowers but the same pod setting percentage of 80% for CDC Sedley, and a lower percentage across eight cultivars. Late nodes produced pods with greater growth rates and shorter filling times, resulting in fewer but similar sized pods. The largest pods were found on nodes with fewer flowers and when moisture was adequate during filling. Drought stress in 2007 occurred and lowered pod setting to 60% and shortened the effective pod‐filling period during late reproductive drought. During the two wet years, higher N rates increased late‐season pod growth rate, but not flower numbers. An increase in late node and flower production may further improve yield, particularly in large‐seeded cultivars.

The Influence of No-till Farming on Durum Wheat Mycorrhization in a Semi-Arid Region: A Long-Term Field Experiment

Maintaining a reliable and sustainable agricultural production system has become one of the major concerns of producers in arid and semi-arid regions. Simplifying farming techniques and practicing Direct Seedling (DS) could contribute to insure the sustainability of agriculture, preserving the natural resources and the environment. Direct Seedling based on limiting soil plowing has a potential number of benefits, including reduced production costs and soil erosion. Associated with the organic mulch, this technique improves the soil fertility and favors the establishment of root symbioses. Given the importance of the no-till farming techniques, the present research work aims to compare the effects of DS and those of Conventional Seedling (CS) on the evolution of arbuscular mycorrhizal symbiosis in durum wheat (Triticum durum Desf) roots, cultivated in the field for five years. Soil and root samples were collected during three different cropping stages at two different treatments. The results of Arbuscular Mycorrhizal Fungi (AMF) root colonization kinetics have shown an increase in the percentage of arbuscules and a decrease in vesicles for plants sampled from a DS field compared to those from CS. Effects of the DS on the mycorrhizal parameters appears clearly in the fourth year of the experiment and continues in the fifth year, with an arbuscule percentage reaching 80% in a DS field and not exceeding 21% in a CS field. Soil phospholipid fatty acids (PLFA) C16:1ω5 (biomarker of AMF) and C18:2ω 6, 9 (biomarker of saprophytic/ectomycorrhizal fungi) demonstrate that no-till practice improves AMF biomass and saprotrophic/ectomycorrhizal fungal biomasses by 52 and 159%, respectively, in comparison with those found in a CS field. In both treatments, no-till farming and CS plots, the AMF biomass is higher than saprotrophic/ectomycorrhizal biomasses. The natural biodiversity of AMF is also enhanced in a no-till field. In addition, an increase in the relative abundance of six families of Glomeromycota (Gigasporaceae, Diversisporaceae, Scutellosporaceae, Entrophosporaceae, Acaulosporaceae, Dentiscutataceae) was observed. To summarize, the present study highlights the importance of no-till practice as an approach to restore the microbiome in soils disturbed by tillage in semi-arid regions.

Weed Seed Decay in No-Till Field and Planted Riparian Buffer Zone

Field management practices can alter the physical and chemical properties of the soil, also causing changes to the seed bank. Alterations can also occur to the soil microbial community, which in turn can increase or diminish the process of weed seed decay. In this research, the issue of seed degradation was studied in an undisturbed and a no-till soil, trying not only to uncover where seeds are more degraded, but also to investigate the microbial activities that could be involved in this process. Six different weed species, commonly found in northern Italy, were used: Abutilon theopharsti, Alopecurus myosuroides, Amaranthus retroflexus, Digitaria sanguinalis, Portulaca oleracea and Sorghum halepense. Seed decay was tested in two different sites, a no-till field and the adjacent buffer zone. Soil microbial activity was also measured using the Fertimetro, an approach based on the degradation of cotton and silk threads buried in the soil for one week. Degradation of the buried seeds was higher in the no-till field soil than in the buffer strip for all the studied species as was the microbial cellulolytic activity. Even though the buffer strip soil is an undisturbed habitat and resulted as having higher organic matter, the no-till soil conditions appeared more unfavourable to seed viability. Our findings suggest that no-till management can improve weed seed suppression in the soil. Moreover, cellulolytic microorganisms play an important role in seedbank longevity, so cellulolytic activity surveys could be used as an early monitoring bioindicator for weed seed suppression in soil.

Measurements and simulations of compaction effects on the least limiting water range of a no-till Oxisol

No-till has many environmental advantages, but concerns are growing about vehicle-induced topsoil compaction limiting crop growth. We performed a wheeling experiment in a long-term no-till field on an Oxisol with sandy loam texture. The objectives were to measure changes in soil bulk density and corresponding impacts on the least limiting water range (LLWR) due to passage of a maize harvester, and to compare bulk density and LLWR measurements with values simulated using the SoilFlex-LLWR soil compaction model. Soil cores were sampled before and after wheeling, for bulk density measurements and to determine LLWR. Simulated increase in bulk density due to vehicle wheeling agreed well with measurements. However, simulated LLWR and its decrease with compaction were inaccurate. This was ascribed to the pedo-transfer function used in SoilFlex-LLWR to estimate LLWR parameters, which was developed based on data from conventionally tilled sugarcane fields, whereas our site was a long-term no-till soil under a wheat/soybean–maize/black oats rotation. Our measurements showed that LLWR was strongly restricted by soil penetration resistance, which was not captured by the pedo-transfer function incorporated in SoilFlex-LLWR. For better prediction of LLWR, we recommend development of specific pedo-transfer functions or of mechanistic models that can be incorporated in SoilFlex-LLWR.

Disk-till vs. no-till maize grass- and alfalfa-reference single (average) and basal (dual) crop coefficients

Disk-till (DT) and no-till (NT) maize (Zea mays L.) water use, crop growth characteristics, and microclimatic differences have been shown to differ. With these differences, it becomes essential that maize be managed differently under these tillage practices in terms of irrigation, and hence, it is indispensable that tools to effectively implement irrigation management be developed. However, water management tools such as crop coefficients that account for tillage practices are extremely rare. To investigate and develop better management tools, this research aimed to develop single (average) (Kc) and basal (dual) (Kcb) daily grass- and alfalfa reference crop coefficients (Kco and Kcr, respectively) using measured crop evapotranspiration at two carefully and cautiously -managed producer fields (disk-till and no-till fields) at Holdrege, Nebraska for 2011, 2012, and 2013 growing seasons. Both Kc and Kcb differed among DT and NT maize in that NT maize showed lower Kc and Kcb during pre-anthesis and higher Kc and Kcb during post-anthesis, and the period of maximum Kc and Kcb occurred later in the crop growing season. Specifically, the magnitude of these differences in Kc values were 56%, 29%, 1%, 8%, 47%, and 41% for May, June, July, August, September, and October, respectively, i.e., greater in early and late season, but smaller in mid-season. Kcb presented similar trends within the season. Kcb exhibited 70% lower magnitudes than Kc, due to minimized evaporation effects on or around precipitation events and hence had reasonably strong relationship with leaf area index. Daily crop coefficients were correlated with two types of base scales: days after planting (DAP) and cumulative growing degree days (CGDD). It is demonstrated with evidence that CGDD was a better predictor of seasonal variation in Kc and Kcb. The relationships between Kc (both Kcr and Kco) and Kcb (both Kcbr and Kcbo) vs. DAP and CGDD for both DT and NT maize during the three growing seasons in the form of transferable polynomial equations were also presented. The crop coefficients for DT and NT maize and their estimation equations presented in this research are novel and have immense application in the task of accurate quantification of maize evapotranspiration and manage irrigation under these two contrasting tillage systems.

No-tillage did not increase organic carbon storage but stimulated N2O emissions in an intensively cultivated sandy loam soil: A negative climate effect

Although numerous studies have been conducted on the effects of no-tillage on carbon (C) sequestration in agricultural systems, there is still no consensus on the balance between the potential of C sequestration and nitrous oxide (N2O) or nitric oxide (NO) emissions. A no-tillage field experiment in the North China Plain was established in 2006 and the influence of no-tillage on N2O and NO emissions was monitored under an annual wheat-maize cropping system. The study included four treatments: no-tillage (NT) and conventional tillage (CT) soils amended with N fertilizer at a rate of 225 kg N ha–1 for wheat and 195 kg N ha–1 for maize (NTN and CTN) and without N fertilizer (NT0 and CT0). Three years of no-tillage significantly (p < 0.05) increased soil organic C (SOC) content by 12.2% in the 0–5 cm soil layer, possibly due to the surface aggregation of organic C derived from crop roots and exudates, but did not alter SOC pool in the 0–30 cm profile. Annual N2O emissions in the NT0 and CT0 treatments were 0.53 and 0.57 kg N2O-N ha–1, respectively, and were significantly (p < 0.05) increased to 0.96 kg N2O-N ha–1 in CTN and to 1.23 kg N2O-N ha–1 in NTN. Remarkable differences in N2O emissions between CTN and NTN were observed during the maize growing season. In contrast, NO emissions were not affected by the tillage regimes regardless of N fertilization. The mean ratios of NO/N2O fluxes in N-unfertilized plots were 0.26–0.29 and 1.79–2.11 for the maize and wheat season, respectively, indicating that both NO and N2O were primarily derived from denitrification during the maize growing season and from nitrification under wheat cultivation. Under N-fertilized plots, the ratios increased to 1.44–2.02 and 5.00–6.03 for the maize and wheat season, respectively, with significantly (p < 0.05) lower values in NTN plots than in CTN plots. The N2O emission factors for N applied in the wheat-maize rotation system were 0.16% and 0.09% for NTN and CTN, respectively, which was far lower than the IPCC Tier 1 default value (1.0%), primarily due to the absence of irrigation after fertilization in maize season and low temperature in wheat season. The results suggest that the 3-year no-tillage regime with residue removal did not substantially increase C storage in the 0–30 cm profile, but stimulated N2O emissions primarily by increasing denitrification.

Soil Health of Recently Converted No-till Corn Fields in Maine

ABSTRACTNo-till (NT) forage production in Northeast United States is growing due to farmers’ desire to reduce costs. Soil samples (15cm deep), soil penetrometer values (depth to 300 psi), and earthworm midden counts were collected from 59 fields on 14 dairy farms in Maine planted to corn. Of the 59 fields sampled, 13 fields received light tillage in the sampling year, 40 had not been tilled within 5 years, and 6 fields had not been tilled for a minimum of 12 years. Median soil health scores (SHS) varied among farms, from 23 to 43 based on the 0 to 50 Woods End SHS scale, based more on past soil management. Most soil quality attributes were significantly correlated indicating that they were useful predictors of soil quality. Among fields not tilled in 5 years, we found no relationship of SHS to time in NT. Fields with greater earthworm activity had higher SHS indicating increased biological activity and potentially improved productivity resulting from better drainage and aeration. Farmers were asked to identify their highest and lowest soil quality fields, but according to the SHS, they were 56 percent successful. Three cornfields on three different farms were NT planted into herbicide killed long-term perennial hay fields; each of these had the highest SHS, but no farmer recognized that. More education on rotating perennial forage crops with NT corn is needed. No-till forage production can improve soil health, reduce fuel and labor costs by more than $50/acre, and residue cover can reduce soil erosion impacts.

The Use of Different Hot Foam Doses for Weed Control

Thermal weed control technology plays an important role in managing weeds in synthetic herbicide-free systems, particularly in organic agriculture. The use of hot foam represents an evolution of the hot water weed control thermal method, modified by the addition of biodegradable foaming agents. The aim of this study was to test the weeding effect of different five hot foam doses, in two sites of different weed composition fields [i.e., Festuca arundinacea (Schreb.), Taraxacum officinale (Weber) and Plantago lanceolata (L.)], by evaluating the devitalisation of weeds, their regrowth, the weed dry biomass at the end of the experiment and the temperature of hot foam as affected by different foam doses. The results showed that the effect of the hot foam doses differed with the different infested weed species experiments. In the Festuca arundinacea (Schreb.) infested field, all doses from 3.33 L m−2 to 8.33 L m−2 led to a 100% weed cover devitalisation and a lower weed dry biomass compared to the dose of 1.67 L m−2, whereas the weed regrowth was similar when all doses were applied. In the Taraxacum officinale (Weber) and Plantago lanceolata (L.) infested fields, doses from 5.00 L m−2 to 8.33 L m−2 in site I and from 3.33 L m−2 to 8.33 L m−2 in site II led to 100% of weed cover devitalisation. The highest doses of 6.67 L m−2 and 8.33 L m−2 led to a slower weed regrowth and a lower weed dry biomass compared to the other doses. The time needed for weeds to again cover 50%, after the 100% devitalisation, was, on average, one month when all doses were applied in the Festuca arundinacea (Schreb.) infested field, whereas in the Taraxacum officinale (Weber) and Plantago lanceolata (L.) fields, this delay was estimated only when doses of 6.67 L m−2 and 8.33 L m−2 were used in site I and a dose of 8.33 L m−2 in site II. Thus, in the Festuca arundinacea (Schreb.) field experiments hot foam doses from 3.33 L m−2 to 8.33 L m−2 were effective in controlling weeds, and the use of the lowest dose (i.e., 3.33 L m−2) is recommended. However, for Taraxacum officinale (Weber) and Plantago lanceolata (L.) the highest doses are recommended (i.e., 6.67 L m−2 and 8.33 L m−2), as these led to 100% weed devitalisation, slower regrowth, and lower weed dry biomass than other doses. A delay in the regrowth of weeds by 30 days can lead to the hypothesis that the future application of hot foam as a desiccant in no-till field bands, before the transplant of high-income vegetable crops, will provide a competitive advantage against weeds.

Dynamics of Measured and Simulated Dissolved Phosphorus in Runoff from Winter-Applied Dairy Manure.

Agricultural P loss from fields is an issue due to water quality degradation. Better information is needed on the P loss in runoff from dairy manure applied in winter and the ability to reliably simulate P loss by computer models. We monitored P in runoff during two winters from chisel-tilled and no-till field plots that had liquid dairy manure applied in December or January. Runoff total P was dominated by nondissolved forms when soils were bare and unfrozen. Runoff from snow-covered, frozen soils had much less sediment and sediment-related P, and much more dissolved P. Transport of manure solids was greatest when manure was applied on top of snow and runoff shortly after application was caused by snowmelt. Dissolved P concentrations in runoff were greater when manure was applied on top of snow because manure liquid remained in the snowpack and allowed more P to be available for loss. Dissolved runoff P also increased as the amount of rain or snowmelt that became runoff (runoff ratio) increased. The SurPhos manure P runoff model reliably simulated these processes to provide realistic predictions of dissolved P in runoff from surface manure. Overall, for liquid dairy manure applied in winter, dissolved P concentrations in runoff can be decreased if manure is applied onto bare, unfrozen soil, or if runoff ratio can be reduced, perhaps through greater soil surface roughness from fall tillage. Both management approaches will allow more manure P to infiltrate into soil and less move in runoff. SurPhos is a tool that can reliably evaluate P loss for different management and policy scenarios for winter manure application.

Dryland Organic Farming Partially Offsets Negative Effects of Highly Simplified Agricultural Landscapes on Forbs, Bees, and Bee-Flower Networks.

Industrialized farming practices result in simplified agricultural landscapes, reduced biodiversity, and degraded species-interaction networks. Thus far, most research assessing the combined effects of farming systems and landscape complexity on beneficial insects has been conducted in relatively diversified and mesic systems and may not represent the large-scale, monoculture-based dryland agriculture that dominates many regions worldwide. Specifically, the effects of farming systems on forbs, bees, and their interactions are poorly understood in highly simplified dryland landscapes such as those in the Northern Great Plains, United States, an area globally important for conventional and organic small grain, pulse, forage, and oilseed production. During a 3-yr (2013-2015) study, we assessed 1) the effects of dryland no-till conventional and tilled organic farming on forbs, bees, and bee-flower networks and 2) the relationship between natural habitat and bee abundance. Flower density and richness were greater in tilled organic fields than in no-till conventional fields, and forb community composition differed between farming systems. We observed high bee diversity (109 taxa) in this highly simplified landscape, and bee abundance, richness, and community composition were similar between systems. Compared with tilled organic fields, bee-flower interactions in no-till conventional fields were poorly connected, suggesting these systems maintain relatively impoverished plant-pollinator networks. Natural habitat (11% of the landscape) did not affect small-bodied bee abundance in either farming system but positively affected large-bodied bees within 2,000 m of crop-field centers. In highly simplified agricultural landscapes, dryland organic farming and no-till conventional farming together support relatively high bee diversity, presumably because dryland organic farming enhances floral resources and bee-flower networks, and no-till management in conventional farming provides undisturbed ground-nesting habitats for wild bees (Hymenoptera: Apoidea).

Compositional tracking of dissolved organic matter in semiarid wheat-based cropping systems using fluorescence EEMs-PARAFAC and absorbance spectroscopy

We conducted this study to quantify long-term cropping related changes in soil organic carbon (SOC) stocks and characterize the optical properties of dissolved organic matter (DOM) after a decadal on-farm experiment in Montana, USA. Soil samples (0–50 cm) were collected from minimum till (MT) and no-till (NT) fields under fallow-winter wheat (Triticum aestivum L.; F-W) and pea-winter wheat (Pisum sativum L.; P-W) rotations. Stocks of SOC(0–50 cm) averaged 65.6 Mg C ha−1 and 60.6 Mg C ha−1 for P-W and F-W, respectively. The net SOC accretion rate for P-W equated to 0.61 Mg ha−1 yr−1 relative to F-W. We used absorbance spectroscopy and excitation-emission matrices to characterize DOM composition of samples collected from MT F-W and NT P-W. The two cropping systems exhibited similar estimates of aromaticity (absorbance at 254 nm; 0.33–0.39 a.u.) and humification index (1.83–1.86). Parallel factor (PARAFAC) analysis revealed humic-like (C1, C2), monolignol/amino acid-like (C3), and amino acid-/tannin-like (C4) components with equivalent fluorescent intensities among MT F-W and NT P-W. Fluorescence efficiencies increased with depth, suggesting a shift from larger, plant-like material to smaller, microbial-derived precursors. Overall, we found DOM composition to be minimally affected by cropping systems in this semiarid climate of the northern Great Plains.

Gypsum amendment effects on micromorphology and aggregation in no-till Mollisols and Alfisols from western Ohio, USA

Synthetic gypsum, a by-product of electricity generation, is used as a soil amendment to overcome water ponding, improve soil and water quality, improve field conditions to support farm equipment, and reduce the variability of crop yield in no-till fields by improving hydrology. Gypsum is a source of soluble calcium (Ca) that improves physical properties of the soil by promoting clay aggregation, thereby increasing water infiltration rates and movement through the soil profile. Undisturbed soil samples from Brookston and Celina soils in Ohio, USA were collected to a depth of 75 cm in agricultural fields treated with gypsum for 0, 4, and 12 years to determine changes in chemical and physical properties. Gypsum applications increased exchangeable Ca and Ca: Mg ratios, and promoted clay flocculation and improved soil structure. Mean weight diameter of aggregates increased with gypsum treatment at most depths in both soils. Micromorphological analysis showed variations in porosity (ɸ), pore size distribution, pore shape and aggregate size related to gypsum treatment, soil, and soil depth. There were no consistent responses to years of gypsum application. Gypsum treated soils had higher porosity than untreated soils in all depths <75 cm and a higher percentage of micropores and mesopores compared to the control. Also, gypsum treated soils had larger aggregates than the control for all soil depths examined. Aggregates <100 μm predominated in the Brookston control soils, and < 200 μm aggregates dominated the Celina control soils. However, there was no prevailing aggregate size for gypsum treated soils. In conclusion, our study found positive effects of gypsum on most properties measured; although, not consistently related to years of gypsum applications to both soils.

WIND-ERODED NITROGEN BALANCE IN AN ENTIC HAPLUSTOLL UNDER DIFFERENT TILLAGE CONDITIONS

Little information is available on the combined effect of weather conditions and tillage systems on nitrogen lost from wind erosion. A field study was carried out on an Entic Haplustoll to analyze N content in the eroded material. Field measurements were made during the winter fallow (WF) and summer fallow (SF) periods in conventional (CT) and a no-till (NT) fields. Winters are more humid and less windy than summers. Results showed that there were N losses and gains by the wind with both tillage systems and in both seasons. Highest N gains in the crop cycle were 17.1 kg ha-1 and maximum losses 7.5 kg ha-1. N gains were detected under high mass flow (the amount of wind-transported material entering the plots from external sources), vegetation cover and soil surface roughness conditions. When these variables were low, N was lost (or gains were low). Tillage system affected N transport more than season, through its effect on the soil surface cover (mainly with NT) or soil surface roughness (mainly with CT). Only when the mean wind speed was 2.3 times higher than the threshold wind speed was the effect of tillage on N transport by wind negligible under both NT and CT.

Harvester ant nest distribution depends on soil disturbance regime

Nest densities of harvester ants (Messor barbarus) are high in rain-fed cereal fields in north-eastern Spain where the ants remove large quantities of seeds, contributing to reductions in weed populations. The distribution of harvester ant nests within a field can influence the effectiveness of ants as weed seed predators because areas with low ant nest density have lower weed seed removal rates. Tillage can disturb or even kill ant colonies and may be an important factor explaining the distribution of nests within fields. During the summers of 2011–2013, the number of nests in a 50 × 50 m area in 4 tilled and 3 no-till fields were counted. Tilled fields were disturbed twice a year, in November before cereal seeding and in July, after cereal harvest, whereas no-till fields had no soil disturbance. Ant nests were evenly spaced in no-till fields whereas nests were randomly distributed in tilled fields. Our results provide evidence that no-till in cereal fields promotes a more even distribution of M. barbarus nests, which should result in higher and more regular levels of weed seed predation across the field.

Response of Organic Matter Decomposition to No-Tillage Adoption Evaluated by the Tea Bag Technique

Organic matter (OM) decomposition is a fundamental ecosystem service in conservation agriculture, but the response of this process to the conversion from conventional tillage (CT) to no-tillage (NT) systems is not fully understood, especially during the transition period. Here, using a litterbag experiment (tea bag technique), we studied OM decomposition in a chronosequence of NT fields of different ages since conversion from CT (1 to 7 years) around Beauvais (northern France). We found that, in contrast with physico-chemical soil properties, the decomposition of both high quality (green tea) and low quality (rooibos tea) organic matter was significantly correlated with the NT age. Irrespective of the OM quality, the OM mass losses linearly increased with the time span since conversion from CT to NT. Taken together, our results suggest that adopting NT practices provides more favorable habitats for microorganisms involved in OM decomposition.

Weeds on Soybeans Crop After the Application of the Association of the Herbicides Imazapic + Imazapyr on Different Liming Rates in a No-till Cropping System

The repeated use of the herbicide glyphosate has selected weed resistant species to this molecule. The combination of the tank-mix imazapic + imazapyr (Cultivance® technology) turns out being an alternative on the management of glyphosate resistant weeds. The interaction of these molecules with the soil’s chemical properties with the spraying frequency, and the weed diversity are yet unknown. This study evaluated the effects of liming at the weed incidence on the soybeans crop treated with the association of herbicides imazapic + imazapyr in a no-till cropping system. The experiment was installed at the field in a RCBD with four replications. The experiment was conducted in a factorial arrangement 5 × 2 with five rates of calcitic limestone (0, 2.5, 5, 12.5, and 30 ton/ha) and two corresponding to the presence or absence of the herbicides imazapic + imazapyr (rate of 100 g/ha of the commercial product Soyvance®) sprayed in a spray-plant system. After 40 months of surface-liming, the soybean cultivar Lancer® was planted in a no-till field, and it was evaluated: frequency and abundance of weeds, and the chemical soil parameters: pH, Ca, H+Al, and Mg at the depth of 0-10 cm. The most abundant weeds observed were: Desmodium spp., Schlechtendalia luzulifolia, Digitaria horizontalis, Raphanus sativus and Cyperus spp., with predominance of dicot species. In conclusion, as the surface-liming rate was increased, the greater the frequency of dicot weeds, and the lesser the monocots were found in the area.