No-till Cropping Systems Research Articles

Carbon (δ

Following cultivation, substantial loss of soil organic matter occurs in surface soil layers. No-till is an agronomic practice to reverse or slow the loss of soil organic matter. We reviewed 95 research papers that used 13C natural abundance of soils to quantify the impact of tillage on the C dynamics of cropping systems. New C (from current cropping systems) accumulated in the surface soil under no-till, whereas the most extreme cultivation (mouldboard ploughing) mixed new C throughout the soil. There was a decline in soil C with years of cultivation. Compared with land that had been tilled, no-till generally had little impact on the accumulation on soil organic C. Tillage and residue retention caused stratification in C stocks that depended on tillage depth, with the highest C concentrations and stocks found in the surface under no-till. Shifts in the δ13C signature indicated significant exchange of ‘new’ C for the original (old) C. Tillage methods had no impact on the size and δ13C signature of the microbial biomass pool. Change in δ13C indicates that microbial biomass rapidly incorporates new carbon. The largest change in the δ13C values (Δ13C) was observed in the coarse sand fraction, whereas the smallest change occurred in the clay fraction. Comparison of conventional vs no-till showed inconsistent results on the effect of tillage on C in the different particle size fractions. Natural 13C abundance data show that no-till cropping systems do not result in increases in soil organic C in the top 0.30 m of soil.

Acúmulo e eficiência no uso de nutrientes em sistemas de produção de safrinha em plantio direto

Abstract: The objective of this work was to evaluate phytomass production, nutrient cycling, and efficiency of nutrient use by single and intercropped crop systems, in the second crop, under no-tillage. The experiment was carried out during the second crop of 2014 and 2015 in the Cerrado biome of the state of Mato Grosso, Brazil, in a randomized complete block design, with nine treatments and four replicates. In 2014, the systems were evaluated at 63, 93, 124, and 157 days after sowing; and, in 2015, they were evaluated at flowering and senescence. The concentrations of nitrogen, phosphorus, potassium, calcium, and magnesium were determined. In 2014, the single crop systems Urochloa ruziziensis, Cajanus cajan, and Pennisetum glaucum showed the largest accumulations of phytomass and nutrients. In 2015, the intercropped systems showed the largest accumulations of phytomass, the largest nutrient cycling, and the highest nutrient use efficiency. In the no-tillage crop systems, U. ruziziensis, either in single cultivation or intercropped with corn and sunflower, increased phytomass. The most efficient systems for the use of all nutrients, in the Cerrado of Mato Grosso, are the intercropping of sunflower with U. ruziziensis, corn with U. ruziziensis, and corn with Crotalaria spectabilis.

Multispecies cover cropping promotes soil health in no-tillage cropping systems of North Carolina

Moving agricultural production systems toward a greater level of soil health is needed for sustainability. Conservation agricultural systems utilizing no or minimum tillage are an important step forward, but enhancing carbon (C) inputs with diverse cover crops and facilitating biologically active nitrogen (N) cycling are also needed. Summer cash-crop systems, particularly in the warm-humid region of the southeastern United States, may benefit from multispecies winter cover cropping if sufficient biomass were produced. We implemented a research and demonstration project utilizing multispecies cover cropping in 15 counties of North Carolina during 2015 to 2019 to assess biomass production and its effect on surface-soil properties. Winter cover crop biomass production was variable among locations, but exceeded 3,790 kg ha–1 in one-third of trials. Nitrogen contained in aboveground cover crop biomass exceeded 60 kg ha–1 in the upper third of trials. Of 30 soil properties measured in each site-year (n = 31) at depths of 0 to 5 and 5 to 15 cm, soil-test biological activity, C mineralization during 24 days, total soil N, and Mehlich-III phosphorus (P) and potassium (K) were most consistently affected when comparing multispecies cover cropping with either no or single-species cover cropping. Despite relatively short duration of evaluations (i.e., mostly one to two years), we were able to elucidate that winter multispecies cover cropping has potential to improve soil health conditions in the region. Soil-test biological activity demonstrated the living nature of soil and was sensitive to conservation agricultural management. The support of a hands-on farmer and adviser network encouraged success.

Soybean growth and foliar phosphorus concentration mediated by arbuscular mycorrhizal fungi from soils under different no-till cropping systems

Soil use and management modify mycorrhizal interactions, but how these changes affect the growth and nutrition of crops under different contexts has been poorly studied. The objective of this study was to evaluate the effects of arbuscular mycorrhizal fungal (AMF) spore communities belonging to two no-till cropping systems (soybean monoculture and soybean-maize rotation), and uncultivated grasslands replicated at four locations along a regional geographic gradient on soybean mycorrhizal colonization and performance. At a regional scale, AMF spore richness was higher in uncultivated grasslands, intermediate in crop rotations, and lower in monocultures. Arbuscular mycorrhizal colonization in soybean roots was also higher in uncultivated soils but did not differ between no-tillage systems. Soybean growth was positively affected by AMF from uncultivated grasslands in comparison to control without AMF. Instead, there were no significant effects of AMF from no-till cropping systems. Foliar P concentration was lower in monocultures irrespective of AMF. At the local scale, patterns were highly variable and differed between locations. These results highlight the importance of scales for management decisions in agriculture and add further support for the context-dependent nature of mycorrhizal interactions.

Soil management and diverse crop rotation can mitigate early-stage no-till compaction and improve least limiting water range in a Ferralsol

No-till management systems tend to cause soil compaction in the early years of their establishment. Soil compaction reduces crop production due to restrictions on root development. Management strategies combining crop rotation and soil conservation practices still need to be researched as potential strategies to mitigate no-till soil physical constraints in tropical regions with prolonged drought periods and still promote agricultural sustainability. The objective of this study was to determine if soil specific management could mitigate early-stage no-till compaction and improve least limiting water range in a Rhodic Ferralsol. We hypothesized that no-till cropping systems with concomitant conservation practices –soil fertilization, crop rotation, and intercropped brachiaria grass– would improve soil physical quality (SPQ) and still achieve high crop yields in a tropical region with dry winters and frequent dry spells during wet season. Six no-till cropping systems were tested: soybean monoculture (T1); corn monoculture (T2); corn and soybean rotation (T3); corn and soybean rotation with intercropped brachiaria (T4); and two more with increased fertilization: corn and soybean rotation with intercropped brachiaria (T5), and corn and soybean rotation (T6). Least limiting water range (LLWR) was used as an indicator of SPQ. LLWR is computed as a function of bulk density (Bd), and it is defined as the range of soil water content in which physical constraints to plant growth are at minimal. Its critical limits are water contents associated with field capacity and air-filled porosity (upper limits), along with wilting point and soil resistance (lower limits). For each Bd, there is a LLWR value: the span between the upper limit and the lower limit. An adaptation of LLWR, in which we substituted the wilting point by the critical water content (θ*), was also tested (LLWR*). Critical Bd (BdC) value was 1.30 Mg m−3 for LLWR and LLWR*. In monoculture treatments (T1 and T2) the maximum Bd values exceeded the BdC (LLWR = LLWR * = 0) and negatively correlated with crop yield. Alternatively, cropping systems with diverse crop rotation (corn/soybean/brachiaria) showed greater values of LLWR and LLWR* and less soil compaction than monoculture systems. Usage of LLWR* evinced water stress was the main limiting plant growth factor; viz. θ* was more limiting than mechanical resistance and deficient aeration. These results support the hypothesis that the use of soil conservation practices and crop rotation during initial years of no-till farming contributes favorably to SPQ without compromising crop production.

The dos and don'ts of no-till continuous cropping: Evidence from wheat yield and nitrogen use efficiency

Abstract When crop-pasture rotation is converted to a single fallow/soybean or winter crop/soybean annual cropping, wheat grain yield declines progressively as the annual cropping phase lengthens, regardless of the tillage system. This decline can be attributed to i) depletion of the soil nutrient supply capacity and ii) subtle but cumulative degradation of soil physical properties. The objectives of this study were to disentangle and quantify the limitations on wheat yield imposed by these processes, and to identify the cropping sequence that preserves soil quality and enables high wheat yield. Wheat was grown for two years at three nitrogen (N) fertilization rates (0, 80 and 190 kg ha−1) in soils after a 20-years experiment with six cropping systems. The cropping systems are crop-pasture rotations with tillage (ROT_CT) or no-till (ROT_NT), continuous cropping with no-till and high frequency of sorghum and maize (CC_NTC4) or soybean and sunflower (CC_NTC3) or winter fallow (CC_NTWF), and continuous annual cropping under conventional tillage (CC_CT). Soil quality was assessed based on chemical (soil organic carbon, total soil N concentration and potentially mineralizable N) and physical properties (field water infiltration rate and soil aggregate stability). In each system, we estimated the yield gap due to N supply ( Y g N ) limitations and the yield gap due to soil properties other than N supply limitations ( Y g o t h e r s ), so that the total yield gap ( Y g T ) is the sum of Y g N and Y g o t h e r s . Systems that degraded chemical and physical properties had lower yield, grain N concentration and fertilizer N use efficiency (NUEf, kg of grain kg−1 of N added). Only two systems, ROT_NT and CC_NTC4, achieved Y m a x (7.2 Mg ha-1). For these two systems Y g T = Y g N . For the other systems, the percentage of Y g T explained by Y g o t h e r s varied between 23 % and 50 %. Rotations that increased the soil N supply (N uptake with no N fertilizer) also increased NUEf. Wheat under ROT_NT reached the maximum yield obtained under CC_CT with 45 % less N fertilizer (104 vs 190 kg ha−1) and higher NUEf (50 vs 27 kg kg−1). Comparing ROT_NT and CC_NTC4 to other continuous no-till cropping systems (CC_NTWF and CC_NTC3), the N fertilizer required was increased from 104 and 107 to 152 and 163 kg ha-1, respectively. In conclusion, rotating annual crops under no-till is not enough to preserve soil productivity. Sustainable intensification under continuous no-till would require either re-balancing crop sequences towards crop-pasture rotations or a shift towards a lower frequency of soybean in favor of higher frequency of maize and sorghum in the summer phase of the rotation.

Changes in soil-pores and wheat root geometry due to strategic tillage in a no-tillage cropping system

Tillage management can influence soil physical properties such as soil strength, moisture content, temperature, nutrient and oxygen availability, which in turn can affect crop growth during the early establishment phase. However, a short-term ‘strategic’ conventional tillage (CT) shift in tillage practice in a continuous no-tillage (NT) cropping system may change the soil-pore and root geometry. This study identifies the impact of a tillage regime shift on the belowground soil-pore and root geometry. Micro X-ray computed tomography (µXCT) was used to quantify, measure and compare the soil-pore and root architecture associated with the impact of tillage shift across different plant growth stages. Soil porosity was 12.2% higher under CT in the top 0–100 mm and 7.4% in the bottom 100–200 mm of the soil core compared with NT. Soil-pore distribution, i.e. macroporosity (>75 μm), was 13.4% higher under CT, but mesoporosity (30–75 μm) was 9.6% higher under NT. The vertical distributions of root biomass and root architecture measurements (i.e. root length density) in undisturbed soil cores were 9.6% higher under the NT and 8.7% higher under the CT system respectively. These results suggest that low soil disturbance under the continuous NT system may have encouraged accumulation of more root biomass in the top 100 mm depth, thus developing better soil structure. Overall, µXCT image analyses of soil cores indicated that this tillage shift affected the soil total carbon, due to the significantly higher soil-pore (i.e. pore surface area, porosity and average pore size area) and root architecture (i.e. root length density, root surface density and root biomass) measurements under the CT system.

Biology and Management of Vulpia myuros-An Emerging Weed Problem in No-Till Cropping Systems in Europe.

Recently, Vulpia myuros has become a problematic grass weed species in parts of Europe. It is most common in no-till cropping systems. The inherent tolerance to several selective grass weed herbicides is of serious concern to the successful management of V. myuros in arable farming. Here, we reviewed the available knowledge about the biology of V. myuros to identify knowledge gaps and assess management efforts to identify best practices for control. V. myuros is a winter-annual species producing seeds with a short dormancy that can germinate at a wide range of conditions. Seed longevity in the soil is short. Little information is available on the influence of V. myuros on crop yield but some results suggest that yield losses can be significant. The findings provide a better understanding of the weedy characteristics of V. myuros and highlight that management strategies in Europe need to be diversified and integrate preventive and cultural control methods. Finally, we identify some of the management tools that should be considered to minimize the impact of V. myuros on European farming and future needs for research to develop sustainable integrated weed management strategies.

Germination ecology of hairy fleabane (Conyza bonariensis) and its implications for weed management

AbstractHairy fleabane [Conyza bonariensis (L.) Cronquist] is a problematic weed in Australian no-till cropping systems. Consequently, a study was conducted to examine the effect of temperature, light, salt stress, osmotic stress, burial depth, and sorghum crop residue on germination and emergence in two populations (C and W: collected from chick pea [Cicer arietinum L.] and wheat [Triticum aestivum L.] fields, respectively) of C. bonariensis. Both populations were able to germinate over a wide range of alternating day/night temperatures (15/5 to 35/25 C); however, the C population had optimum (and similar) germination over the range of 20/10 and 30/20 C, while the W population showed maximum germination at 25/15 C. A negative relationship was observed between osmotic potential and germination, with 31% and 14% germination of the C and W populations at −0.6 MPa, respectively. These observations suggest that population C was more tolerant to higher osmotic potentials than population W. Seeds of both populations germinated when exposed to a wide range of sodium chloride levels (NaCl, 0 to 200 mM); however, beyond 200 mM NaCl, no germination was observed in either population. Maximum germination of the C (70%) and W (41%) populations was observed on the soil surface with no emergence from a burial depth of 1 cm. The application of sorghum residue at an amount of 6,000 kg ha−1 reduced emergence of the C and W populations by 55% and 58%, respectively, compared with the no-residue treatment. Knowledge gained from this study suggests that the following strategies could be used for more efficacious management of C. bonariensis: (1) a shallow-tillage operation to bury weed seeds in conventional tillage systems, and (2) retention of sorghum residue on the soil surface in no-till systems.

Response of soybean and corn to halauxifen-methyl

AbstractPreplant (PP) herbicide applications are an important tool within an integrated weed management system, specifically in no-till production. An understanding of crop tolerance regarding PP applications is important for effectively integrating a new herbicide into no-till cropping systems. Twelve field trials (six in corn and six in soybean) were conducted over a 2-yr period (2018 and 2019) near Exeter and Ridgetown, ON. The purpose of these studies was to evaluate the tolerance of soybean and corn to halauxifen-methyl applied PP, PRE, or POST at the registered rate (5 g a.i. ha−1) and twice the registered rate (10 g a.i. ha−1), hereafter referred to as the 1× and 2× rate, respectively. All trials were kept weed-free throughout the growing season to remove the confounding effect of weed interference. Halauxifen-methyl applied 14 d preplant (DPP), 7 DPP, 1 DPP, and 5 d after seeding (DAS) at the 1× and 2× rates caused ≤10% visible soybean injury. In contrast, halauxifen-methyl applied POST (cotyledon–unifoliate stage, VE-VC) caused 67% to 87% visible soybean injury, a 50% to 53% reduction in height, 65% to 81% decrease in population, 56% to 67% lower biomass, and 53% to 63% decline in yield. Halauxifen-methyl applied 10 DPP, 5 DPP, 1 DPP, 5 DAS, and POST (spike–one leaf stage, VE-V1) at the 1× and 2× rate caused ≤3% visible corn injury and caused no effect on corn height or biomass. Halauxifen-methyl applied at VE-V1 at the 2× rate reduced corn yield 10%. Based on these studies, the current application restriction of 7 DPP in soybean and 5 DPP in corn is conservative and could be expanded. Expanding the application window of halauxifen-methyl would increase the utility of this herbicide for producers.

Management Strategies on an Upland Soil for Improving Soil Properties

ABSTRACTUpland soils marginal in organic matter, low in soil quality, vulnerable to water and nutrient losses. This study was conducted to determine whether the integration of winter cover crops and soil amendments into no-till cropping systems improve upland soil quality. The effects of winter cover crops (WCCs), broiler litter (BL) and flue gas desulfurization (FGD) gypsum in no-till (NT) corn-soybean rotation on soil physical and biological properties were investigated at Pontotoc, MS on an upland Falkner silt loam soil (fine-silty, siliceous, active, thermic Aquic Paleudalfs). After harvest, soil samples were collected and analyzed for total C (TC) and selected physical and biological properties. Averaged across fertilization treatments, WCCs increased TC, cumulative infiltration and reduced bulk density (BD) and penetration resistance (PR) at 0–5 cm depth as compared to winter fallow (WF). Averaged across WCCs treatments, BL increased infiltration by 51%, and reduced BD and PR by 3% and 24%, respectively, as compared to unfertilized control. Co-application of FGD gypsum with BL reduced BD and PR at 5 cm soil depth by 4% and 5%, respectively. Interestingly, BL did not affect soil microbiological parameters, but the co-application of FGD gypsum with BL resulted in a significant response in soil dehydrogenase activity. On the other hand, cover crop increased ureC (urease C) genes, probably due to conserved soil moisture by cover crop residues. Integration of WCCs, organic and inorganic amendments into no-till corn-soybean appear to improve soil physical, hydrological and microbial properties, which may enhance the efficiency of cropping systems in upland soils.

Effects of long-term grazed crop and pasture systems under no-till on organic matter fractions and selected quality parameters of soil in the Overberg, South Africa

There is limited soil research on semi-arid, grazed no-till crop and pasture systems. The long-term (10 years) effect of three grazed no-till dryland crop and pasture rotation systems, and perennial lucerne pasture were assessed on soil carbon (C) and nitrogen (N) stocks, soil organic matter functional pools and selected soil quality parameters in the Overberg, South Africa. The largest soil C and N stocks (0–30 cm) were found in crop–pasture systems containing wheat and medic/clover (70.2–74.9 Mg C ha−1 and 8.3–8.4 Mg N ha−1), compared with perennial lucerne pasture (63.4 Mg C ha−1 and 7.7 Mg N ha−1) or cropping-only systems (54.7–58.9 Mg C ha−1 and 6.3–6.7 Mg N ha−1). Significantly higher labile C and N (free particulate organic matter fraction) contents were observed in crop–pasture systems (1.37–1.74 g C kg−1 and 0.107–0.110 g N kg−1) than in continuous cropping systems (0.9–1.0 g C kg−1 and 0.042–0.045 g N kg−1), attributed to higher annual C and N inputs and lower extent of soil disturbance. Significant positive correlations were found between soil C and N functional pools and soil quality parameters (soil respiration, effective cation exchange capacity and aggregate stability) and wheat yields. The results show the importance of the medic/clover pasture and wheat rotations in enhancing soil quality in the Overberg region.

Stacking Agricultural Management Tactics to Promote Improvements in Soil Structure and Microbial Activities

Linking agricultural management tactics to quantifiable changes in soil health-related properties is a key objective for increasing adoption of the most favorable management practices. We used two long-term, no-till cropping studies to illustrate the variable patterns of response of soil structure indices and microbial activity to additional management tactics, including crop rotational diversity, residue management and cover cropping. We found that observable effects of management tactics on soil properties were often dependent on the current crop phase sampled, even though the treatments were well-established. In some cases, a single additional management tactic produced a response, two tactics each produced a response and sometimes there were interactions between tactics. However, importantly, we never observed a negative effect for any of the response variables when stacking soil health building practices in no-till cropping systems. The collective results from the two field studies illustrate that soil health improvements with stacking management tactics are not always simply additive and are affected by temporal relationships inherent to the treatments. We conclude that the implementation of multiple positive management tactics increases the likelihood that improvements in soil properties can be documented with one or more of the proxy measures for soil health.

Mining the Drilosphere: Bacterial Communities and Denitrifier Abundance in a No-Till Wheat Cropping System.

Earthworms play important roles in no-till cropping systems by redistributing crop residue to lower soil horizons, providing macropores for root growth, increasing water infiltration, enhancing soil quality and organic matter, and stimulating nitrogen cycling. The soil impacted by earthworm activity, including burrows, casts, and middens, is termed the drilosphere. The objective of this study was to determine the effect of earthworms on soil microbial community composition in the drilosphere at different landscape slope positions. Soil cores (50 cm depth) were extracted from three landscape locations (top, middle, and bottom slope positions) on a sloping aspect of a no-till wheat farm. Soil was sampled at the bottom of the soil core from inside multiple earthworm (Lumbricus terrestris) channels (drilosphere) and from adjacent bulk soil. Bacterial communities were characterized for 16S rRNA gene diversity using high-throughput sequencing and functional denitrifier gene abundance (nirK, nirS, and nosZ) by quantitative PCR. Bacterial communities were structured primarily by the landscape slope position of the soil core followed by source (bulk versus drilosphere soil), with a significant interaction between core position and source. The families AKIW874, Chitinophagaceae, and Comamonadaceae and the genera Amycolatopsis, Caulobacter, Nocardioides, and Variovorax were more abundant in the drilosphere compared to the bulk soil. Most of the individual bacterial taxa enriched in the drilosphere versus bulk soil were members of Actinobacteria, including Micrococcales, Gaiellaceae, Solirubrobacterales, and Mycobacterium. In general, the greatest differences in communities were observed in comparisons of the top and bottom slope positions in which the bottom slope communities had significantly greater richness, diversity, and denitrifier abundance than the top slope position. Populations of denitrifiers (i.e., ratio of nirK+nirS to 16S rRNA) were more abundant in earthworm-impacted soils and there was a significant impact of L. terrestris on soil community composition which was observed only in the top landscape position. There were significant correlations between the abundance of nirK and nirS and taxa within Proteobacteria, Acidobacteria, Actinobacteria, Verrucomicrobia, and Chloroflexi, suggesting a broad diversity of denitrifying bacteria. Earthworms influence the soil microbial communities, but the impact depends on the slope location in a variable landscape, which likely reflects different soil characteristics.

Efecto de la secuencia de cultivos sobre la población nativa de Trichoderma spp. en agricultura sin laboreo

La agricultura ha experimentado un fuerte proceso de cambios que han significado un aumento de las problemáticas sanitarias causadas por patógenos necrotróficos. Diversos trabajos muestran que manejando microorganismos benéfi-cos es posible reducir el impacto de las enfermedades. En base a esto, el objetivo de este trabajo fue determinar el efecto de los cultivos sobre la población de Trichoderma spp. en suelo y en rastrojo, en un sistema agrícola sin laboreo. El monitoreo de la población de Trichoderma spp. se realizó en un experimento con cuatro secuencias de cultivos. Se realizaron muestreos de rastrojo y suelo en primavera y otoño, durante tres años consecutivos. La densidad poblacional de Trichoderma spp. fue determinada mediante el método de dilución y recuento en placa. A su vez, se determinaron las propiedades químicas del suelo de cada tratamiento. Los resultados mostraron que el rastrojo de cebada presentó mayor densidad poblacional de Trichoderma spp. que el rastrojo de otras especies. Las distintas secuencias de cultivo afectaron significativamente la densidad poblacional de este hongo en el suelo. Sin embargo no tuvieron efecto sobre las propiedades químicas del suelo, ni hubo una asociación entre estas y la población de Trichoderma spp. Estos resultados establecen la posibilidad de manejar la población nativa de Trichoderma spp. mediante la elección de los componentes de las secuencias de cultivos, y permiten identificar ambientes más propicios para mantener altas poblaciones de Trichoderma. La identificación de ambientes que favorecen altas poblaciones de Trichoderma podría indicar situaciones más favorables para eventuales inoculaciones del antagonista.

Monitoring soil quality changes in diversified agricultural cropping systems by the Soil Management Assessment Framework (SMAF) in southern Brazil

Assessment and monitoring impacts of agricultural systems on soil quality are imperative to establish best management practices and sustainable land use for mitigating climate change, conserving biodiversity and achieving food and energy security. The SMAF has successfully been tested as an objective tool to quantify land use and management effects on soil quality, including under some Brazilian soil conditions. Nevertheless, the SMAF potential to properly address soil quality changes under contrasting soil and climate conditions, and integrated farming systems must still must be investigated. Thus, a field study was conducted to apply the SMAF guidelines as a strategy for assessing land use (native vegetation, pasture, sugarcane, no-tillage, and integrated crop-livestock systems) effects on soil quality in southern Brazil. Soil samples were taken in three layers (0.0–0.10, 0.10–0.20, 0.20–0.30 m) of clay Ferralsol (traditional agricultural region), Sandy loam Ferralsol and Arenosol (new agricultural frontiers), in the state of Paraná, Brazil. The soil quality indicators investigated were: chemical attributes (pH, phosphorus and potassium), physical (bulk density) and biological (soil organic carbon). Using the SMAF scoring curves, the measured values were transformed (0 to 1 range) and an overall soil quality index (SQI) was calculated. Our findings revealed that long-term conversion from native vegetation to agricultural land uses (i.e., pasture, no-tillage/integrated crop-livestock system, or sugarcane) reduced soil quality assessed by SMAF scores, compromising the soil’s capacity to perform its functions. Nevertheless, conservationist systems, e.g. the no-tillage, associated or not with the integrated crop-livestock system are promising alternative to enhances soil quality by increasing C content and soil chemical fertility compared to degraded pasture or conventional sugarcane cultivation. However, soil physical changes should be monitored to alleviate soil compaction in no-tillage cropping systems. In conclusion, this study provided important insights about soil quality changes induced by land use and diversified cropping systems. In that direction, new studies including a large number of sites, soil types and cropping systems are needed for validating our conclusions in a regional scale, enabling to support decision-making towards more sustainable expansion and intensification of agriculture in Brazil.

A novel framework to detect conventional tillage and no-tillage cropping system effect on cotton growth and development using multi-temporal UAS data

Recent years have witnessed enormous interest in the application of Unmanned Aerial Systems (UAS) for precision agriculture. This study presents a novel approach to use multi-temporal UAS data for comparison of two management practices in cotton, conventional tillage (CT) and no-tillage (NT). The plant parameters considered for the comparison are: canopy height (CH), canopy cover (CC), canopy volume (CV) and Normalized Difference Vegetation Index (NDVI). Initially, the whole study area was divided into approximately one square meter size grids. Measurements were extracted grid wise using high resolution UAS data captured ten times over whole crop growing season of the cotton. One tailed Z-test hypothesis reveals that there is a significant difference between cotton growth under CT and NT for almost all the epochs. With 95% confidence interval, the crop grown under NT found to have taller canopy, higher canopy cover, bigger biomass and higher NDVI, as compared to those under CT cropping system.

Combining roller crimpers and flaming for the termination of cover crops in herbicide-free no-till cropping systems.

The termination of cover crops in conventional no-till systems is mostly conducted mechanically in combination with herbicides. Combining flaming and roller crimpers could be a viable solution to avoid using herbicides for cover crop termination in farming systems where herbicides are banned, or at least to reduce their use in an integrated management approach. This research tested the effects of flaming used in combination with three different types of roller crimpers to terminate a fall-sown cover crop mixture of winter pea and barley. The cover crop termination rate was visually assessed in terms of percentage of green cover provided by cover crop plants at different intervals from the termination date, and estimated using a log-logistic non-linear regression model with four parameters. Machine performance data are also reported. The results show that, irrespective of the roller type, flaming significantly boosted the effect of the roller crimpers. In fact, an economic threshold for cover crop suppression of 85% was reached only when the rollers were used in combination with flaming. Nevertheless, none of the methods were able to reach the 100% of cover crop suppression. In some case, the combined use of flaming and roller crimpers allowed reaching the 90% of cover crop devitalisation, which happened six weeks after the termination date. More importantly, the use of flaming in combination with rollers shortened the time needed to achieve the estimated levels of devitalisation, compared with the rollers used alone. We conclude that flaming is an effective tool to increase the effectiveness of roller crimpers. Nevertheless, further research is needed to identify solutions to overcome the barrier of the high operational costs of flaming, which is constraining its wider adoption by farmers. Future studies could focus, for instance, on the development of a new prototype of combined machine for crimping and flaming the cover crops simultaneously, which could potentially reduce the operational costs.

Rhizobial Inoculation and Molybdenum Fertilization in Peanut Crops Grown in a No Tillage System After 20 Years of Pasture

ABSTRACT: Peanut (Arachis hypogea) is an important legume grain consumed by humans and utilized for effective nutrient cycling in a diverse cropping system. Areas that have been cultivated with perennial pasture for decades may have nutritional deficiencies and lack a sufficient population of atmospheric nitrogen-fixing bacteria. Molybdenum is an essential micronutrient that is part of the enzyme nitrogenase contained within symbiotic Bradyrhizobium bacteria, which are responsible for fixing nitrogen in legumes. Our objective was to evaluate the effects of application of Mo at different rates and a rhizobial inoculant on peanut growth characteristics. The experiment was conducted in the 2009/2010 growing season in a no-tillage cropping system following 20-year use as pasture [Urochloa brizantha (Syn. Brachiaria brizantha)]. The experimental design was a randomized complete block with four replicates. The main plots were characterized by peanut inoculation with Bradyrhizobium inoculant or without, and the split plots were characterized by different rates of molybdenum (0, 50, 100, and 200 g ha-1) applied to leaves in the form of ammonium molybdate. The nutritional status of plants, nodulation (number of nodules and nodule dry matter per plant), nitrogenase activity, and nitrogenase specific activity were evaluated at 45 and 64 days after emergence (DAE). The yield components and kernel yield were evaluated at the end of the growing season. Nitrogenase enzyme activity at 64 DAE approximately doubled, and the number of pods per plant was greater with inoculation than without, both of which led to greater yields of pods and kernels. In long-term pasture areas, inoculation and molybdenum fertilization greater than the currently recommended rate appear to be necessary to increase pod and kernel yield per hectare of peanut when managed under no-tillage.

Response of sunflowers (Helianthus annuus L.) to varying seeding rates and nitrogen fertilizer rates in a no-till cropping system in Saskatchewan

In the past, most sunflower research was conducted in tilled cropping systems and was based on wide row configurations established using precision planters. Little agronomic information is available for the no-till systems predominant in Saskatchewan, where crops are typically seeded in narrow rows using an air drill. Two studies were conducted in Saskatchewan to determine the optimum seeding and nitrogen (N) rates for short-season sunflowers in a no-till cropping system. The N rate study used 5 N rates (10, 30, 50, 70, and 90 kg N ha−1) with the hybrid 63A21. The seeding rate study used 7 seeding rates (37 000, 49 000, 61 000, 74 000, 86 000, 98 000, and 111 000 seeds ha−1) with two cultivars, AC Sierra (open pollinated) and 63A21 (hybrid). There was a linear yield increase as the N rate increased from 10 to 90 kg N ha−1. Based on the N rates tested in this study and current N fertilizer costs below $1 kg−1, sunflower yields and gross returns were most favorable at 90 kg N ha−1. Future N response research with a wider range of N rates is warranted to best determine the optimum N rate. The optimum seeding rate was between 98 000 and 111 000 seeds ha−1 for AC Sierra and between 74 000 and 86 000 seeds ha−1 for 63A21. The optimum plant density, approximately 70 000 to 75 000 plants ha−1, was similar for both cultivars. These results are higher than the current recommended seeding rates for wide-row precision planting systems in areas with a longer growing season.