Reduced Tillage Systems Research Articles

Soil Physical Properties and Soybean Yield as Influenced by Long-Term Tillage Systems and Cover Cropping in the Midsouth USA

A better understanding of the effect of long-term tillage management on soil properties and yield is essential for sustainable food production. This research aimed to evaluate the 37-year impact of different tillage systems and cover cropping on soil hydro-physical properties at 0–15 and 15–30 cm, as well as on soybean [Glycine max (L.) Merr] yield. The long-term experiment was located in Jackson, TN, and the different treatments involved in this study were no-tillage (NT), disk (DP), chisel (CP), moldboard plow (MP), and no-tillage with winter wheat [Triticum aestivum (L.)] cover crop (NTW). Forty-five days after the tillage operation, MP showed a comparable bulk density (BD) with NT, NTW, and CP at 0–15 cm depth. At surface depth, No-tillage systems increased cone penetration resistance (PR) by 12% compared with the reduced tillage systems, and 47% relative to MP. Wet aggregate stability (WAS) at surface depth was 27% and 36% greater for NT systems than for reduced and conventional tillage systems, respectively. Similarly, the geometric mean diameter (GMD) of aggregates was significantly higher under NT and NTW. However, water infiltration and field-saturated hydraulic conductivity (Kfs) did not differ significantly among tillage systems. The greatest soybean yield was obtained from CP and DP, producing 10% higher yield than NTW. Overall, 37 years of no-tillage, with or without simplified cover cropping did not result in a consistent improvement in soybean yield and soil physical properties with the exception of having improved soil aggregation.

Effect of tillage systems on pea crop infestation with weeds

ABSTRACTIn a multi-year experiment, weed infestation of pea crop in three tillage systems was analyzed: a) conventional tillage (CT), b) reduced tillage (RT), and c) no-tillage (NT), and in two terms: 1) at 2–3 pea leaves stage (23–25 stage in BBCH scale) and 2) at the flat pod stage (75–79 BBCH). Treatments conducted in the CT system included shallow ploughing and pre-winter ploughing in the autumn. In the RT system, both these treatments were replaced by double cultivation, whereas only glyphosate treatment was applied in the NT system. In both terms of weed infestation assessment, the highest number and air-dry weight of weeds were determined in the RT system, lower ones in CT and the lowest ones in the NT system. In the first term, the number of weeds m−2 in the RT system was higher by 43.9% than in NT and by 26% than in CT system. Also in the second term was the weed number m−2 in RT higher by 58.6% than in NT and by 27.9% than in CT. Tillage systems differentiated also weed mass in pea crop. In RT, it was 4-fold higher than in NT and over 2-fold higher than in CT.

Modelowanie bilansu węgla organicznego w glebie oraz emisji gazów cieplarnianych w skali regionalnej oraz w Polsce

Celem pracy były symulacje uproszczonego bilansu węgla oraz pochłaniania i emisji gazów cieplarnianych (CO2, CH4, N2O) dla scharakteryzowania potencjału mitygacji zmian klimatu w rolniczym użytkowaniu gruntów ornych. Symulacje wykonywano przy użyciu modelu DNDC dla województw i Polski z użyciem dwudziestoletnich serii danych meteorologicznych. Stwierdzono, że system uprawy płużnej ze zbiorem resztek pożniwnych (a) powodować będzie w Polsce emisję netto tych gazów wynoszącą 0,203 t CO2 ekw. ∙ ha-1 ∙ r-1. Natomiast system uprawy uproszczonej z pozostawieniem na polu resztek pożniwnych (b) oraz system uprawy płużnej z regularnym stosowaniem obornika i zbiorem resztek pożniwnych (c) pochłaniać będą CO2 w ilościach wynoszących odpowiednio: 1,225 i 0,172 t CO2 ekw. ∙ ha-1 ∙ r-1. Uzyskane wyniki sugerują, że w perspektywie średnioterminowej (20 lat), badane systemy uprawy mogą być uznane za praktyki mitygujące zmiany klimatu. Zastosowanie systemów uprawy w pożądanej proporcji w stosunku do areału gruntów ornych w Polsce mogłoby pozwolić na średnie pochłanianie gazów cieplarnianych rzędu 0,556 t CO2 ekw.∙ha 1∙r-1.

Suppression of weeds and weed seeds in the soil by stubbles and no-tillage in an arid maize-winter wheat-common vetch rotation on the Loess Plateau of China

Reduced tillage provides ecological and economic benefits to arable land on the Loess Plateau of China, where soil erosion has long been a serious problem and soil water availability is largely restricted. However, high abundances of weeds in reduced tillage systems cause significant yield losses. In this study, we explored the effects of no-tillage and stubble retention on the number and density of weeds and weed seeds in a 12-year maize-winter wheat-common vetch rotation on the Loess Plateau. Four treatments including conventional tillage, no-tillage, conventional tillage+stubble retention and no-tillage+stubble retention were designed and applied. We found that no-tillage increased the number of weed species and weed density in most of the crops, while stubble retention decreased weed density in maize and tended to suppress weeds in both no-tillage treatments (no-tillage and no-tillage+stubble retention). No-tillage led to an increase in the number of weed species in the weed seedbank and tended to increase seed density during the spring growth of winter wheat, but it decreased seed density during post-vetch fallow. Stubble retention tended to reduce seed density during the spring growth of winter wheat and post-vetch fallow. We concluded that no-tillage can promote weeds in the experimental crop rotation, while stubble retention suppresses weeds in untilled fields. The combined effects of stubble retention and no-tillage on weed suppression varied among the three crops. Based on these results, we recommend stubble retention in untilled legume-crop rotations on the Loess Plateau to improve the control of weeds.

Characterization of Acetolactate Synthase (ALS)-Inhibitor Resistance in Pennsylvania smartweed (Persicaria pensylvanica)

AbstractPennsylvania smartweed [Persicaria pensylvanica(L.) M. Gómez] is a common weed of rice (Oryza sativaL.) in the midsouthern United States and has recently become a concern for farmers because of reduced tillage systems. Acetolactate synthase (ALS) inhibitors have been extensively used for controlling smartweeds in imidazolinone-resistant and conventional rice. In the present study, we confirmed resistance to commonly used ALS inhibitors in rice and characterized the underlying resistance mechanism in aP. pensylvanicabiotype from southeast Missouri. A dose–response experiment was conducted in the greenhouse using bensulfuron-methyl, imazethapyr, and bispyribac-sodium to determine the resistance index (resistance/susceptibility [R/S]) based on GR50estimates. The target-siteALSgene was amplified from R and S plants, and sequences were analyzed for mutations known to confer ALS-inhibitor resistance. TheP. pensylvanicabiotype in question was found to be resistant to bensulfuron-methyl (R/S=2,330), imazethapyr (R/S=12), and bispyribac-sodium (R/S=6). Sequencing of theALSgene from R plants revealed two previously known mutations (Pro-197-Ser, Ala-122-Ser) conferring resistance to sulfonylureas and imidazolinones. This is the first report of ALS-inhibitor resistance inP. pensylvanica.

Soil macrofauna diversity as a key element for building sustainable agriculture in Argentine Pampas

The agricultural activity in the Argentine Pampas, characterized by an important trend towards no-till soybean monocropping, has completely transformed the original Pampas landscape into a monotonous scenario with a continuous succession of farms of very low crop diversity. This process has led to soil physical, chemical and biological degradation in those systems. The increase of crop rotation rates in no-till and reduced tillage systems has been proposed as an alternative with reduced negative impact on soils in the context of conventional agriculture. On the other hand, extensive organic farming is also suggested as an alternative to high-input agriculture systems. In this article, we aim to explore how different variations of farming practices and systems impact soil macrofauna, along an edaphoclimatic gradient in the Pampas region. We studied the following systems: natural grassland (Gr) as indicator of the original community, extensive organic farming (Org), conventional agriculture with no-tillage and three crop rotation levels (Nt-R1, Nt-R2 and Nt-R3), and reduced tillage with two levels of crop rotation (Til and Til-R). We assessed soil macrofauna, with emphasis on earthworm, beetle and ant communities; and soil physical and chemical properties. Macrofaunal taxa composition was significantly affected by both management systems and edaphoclimatic conditions. The Gr community had pronounced differences from all the agricultural systems. The earthworm community from Gr had distinctive features from those of most agricultural systems, with Org and Nt-R3 being the most similar to Gr in native and exotic earthworm species, respectively. The beetle community in Org was the most different one, and the communities from the other systems did not show a pattern related to management. Ant community composition was not determined by management systems, but it was affected by edaphoclimatic conditions. All the studied macrofauna groups had a significant co-variation with soil physical and chemical properties, showing that both the characteristics of each soil relative to the geographic location and the effect of management on abiotic soil attributes have an important effect on soil macrofauna. This study confirms that biodiversity is being lost in Pampas soils, which implies a possible threat to the soil capacity to perform the processes that sustain soil functioning and hence plant productivity. Further considerations about the sustainability of the current agricultural model applied in the Argentine Pampas are needed.

Soil organic matter dynamics under irrigated perennial forage–annual crop rotations

AbstractReduced soil disturbance and increased organic matter inputs in forage production systems may improve soil quality and crop production through their effects on soil organic matter (SOM) dynamics and nutrient cycling. We evaluated the effects of conventional (CV), organic (OR) and reduced‐tillage (RT) management systems on SOM pools in perennial forage–annual crop rotations established on soils previously under long‐term monocropped corn (Zea mays L.) field. The SOM pools evaluated include potentially mineralizable carbon (PMC) and nitrogen (PMN), dissolved organic carbon (DOC) and nitrogen (DON), microbial biomass carbon (MBC) and nitrogen (MBN), inorganic nitrogen (inorganic‐N), soil organic carbon (SOC) and soil total nitrogen (STN). The crop rotation was 3 years of alfalfa (Medicago sativa L.)–grass mixture (2009‐2011) followed by a fourth year of corn (2012) across all management systems. While soils under the RT system had the highest rate of labile carbon (C) and nitrogen (N) accrual, all management systems accumulated SOC and STN during 2009‐2011. The response of different C and N pools was not consistent in 2012 when the fields were transitioned from alfalfa‐grass mixture to corn production. Soil PMN and inorganic‐N contents were significantly greater under CV than other management systems, whereas PMC and MBC remained greater under RT than other management systems. This suggests CV may provide immediate benefits to crop production by increasing N availability, but RT has potential to increase SOC accumulation and improve soil quality in the long‐term under perennial forage–annual crop rotations.

Alternative Management Practices Improve Soil Health Indices in Intensive Vegetable Cropping Systems: A Review

An increase in intensive cropping would benefit society by providing food to a growing population, and vegetable production is an excellent example of intensive cropping systems that are indeed on the rise. Vegetable cropping systems are high-input and generally require large quantities of fertilization, frequent irrigation, and repeated tillage operations. Consequently, an increase in global vegetable production may have seriously negative impacts on soil health and ecosystem services. Yet, not only maintaining but improving soil health is critical to enhancing the sustainability of food production systems. Previous agricultural research mainly focused on field crop systems and largely ignored vegetable cropping systems; consequently, this represents a conspicuous research gap, one that must be addressed in order to make progress towards sustainable food production. Here, we review the literature to gain a better understanding of how management has influenced various soil health indices (soil biology, chemistry, and physical dynamics) and to evaluate the implications for soil ecosystem services in vegetable cropping systems. We found that alternative modifications to conventional vegetable production systems, which resemble methods used in organic or conservation agriculture, tended to improve aspects of soil health. For example, soil amendments generally improved soil chemical indices of health – soil carbon levels and nitrogen reserves in particular. Incorporation of cover crops to vegetable crop rotations tended to improve nitrogen recycling via reduced nitrate leaching risks, increased soil carbon levels, and weed suppression. Reduced tillage systems were rare, presenting an important challenge and opportunity for further improving soil health dynamics in vegetable production. Notably, adopting alternative practices generally had no effect on crop yields, which implies little risk of yield penalties when agronomic management is carefully planned. Our results indicate that future sustainable vegetable cropping systems may embody a blend between organic and conventional ideologies to better maintain or improve soil ecosystem functioning.

Maize responses to reduced tillage, different plant residue mulch and nitrogen fertiliser on granitic sandy soils of Zimbabwe

Mulching in smallholder conservation agriculture (CA) systems is constrained by lack of adequate crop residues. A three-year study assessed the effects of reduced tillage systems combined with different plant residue mulch and nitrogen (N) fertiliser on nitrogen uptake using the normalised difference vegetation index (NDVI), maize growth and yield, and agronomic efficiency. A split plot design with three or four replicates was used. Maize, Hyparrhenia grass, leaf litter, sunnhemp and Tephrosia residue mulch in CA and a conventional control were the main treatments. The N subtreatments were 0, 60 and 120 kg N ha−1. The main treatments had a similar effect on NDVI, and N increased NDVI across the treatments. The conventional practice had taller plants compared with CA. The conventional and CA treatments had a similar effect on maize yields. The different plant residues in CA had a similar effect on yields. Nitrogen increased yield, and 60 and 120 kg N ha−1 had a similar effect. The 60 kg N ha−1 subtreatment had a higher agronomic N efficiency than 120 kg N ha−1. The study demonstrated that CA with different plant residues and the conventional practice give similar yields in the short term.

Impact of agronomy practices on the effects of reduced tillage systems on CH4 and N2O emissions from agricultural fields: A global meta-analysis.

The effect of no- and reduced tillage (NT/RT) on greenhouse gas (GHG) emission was highly variable and may depend on other agronomy practices. However, how the other practices affect the effect of NT/RT on GHG emission remains elusive. Therefore, we conducted a global meta-analysis (including 49 papers with 196 comparisons) to assess the effect of five options (i.e. cropping system, crop residue management, split application of N fertilizer, irrigation, and tillage duration) on the effect of NT/RT on CH4 and N2O emissions from agricultural fields. The results showed that NT/RT significantly mitigated the overall global warming potential (GWP) of CH4 and N2O emissions by 6.6% as compared with conventional tillage (CT). Rotation cropping systems and crop straw remove facilitated no-tillage (NT) to reduce the CH4, N2O, or overall GWP both in upland and paddy field. NT significantly mitigated the overall GWP when the percentage of basal N fertilizer (PBN) >50%, when tillage duration > 10 years or rainfed in upland, while when PBN <50%, when duration between 5 and 10 years, or with continuous flooding in paddy field. RT significantly reduced the overall GWP under single crop monoculture system in upland. These results suggested that assessing the effectiveness of NT/RT on the mitigation of GHG emission should consider the interaction of NT/RT with other agronomy practices and land use type.

Cotton Varietal Responses to Tillage Type in the Upper Southeastern U.S. Coastal Plain

Core Ideas Evaluation of cotton varieties across tillage systems in the upper Southeast coastal plain.Cotton variety selection had a greater impact on development and yield than tillage system.No‐till systems produced slightly lower yields then other conservation tillage systems.No‐till resulted in greater soil compaction than other tillage systems.Current reduced tillage systems produced the highest lint yield during the study. Current understanding of the effects of tillage systems on cotton growth and development of contemporary varieties is limited for producers of the Upper Southeast Coastal Plain of the United States. Tillage studies were conducted in Suffolk, VA, from 2013 to 2016 evaluating conventional, minimal, no‐tillage, and strip‐tillage systems on early season growth, soil compaction, and lint yield of four contemporary varieties using a split‐plot design. Soil compaction was greatest in the no‐till system with yearly depths to a root restrictive layer ranging from 8–26 cm. No‐till resulted in shorter plant heights compared to other tillage methods in 2 out of 4 yr. Relative yield for no‐till was 0.78, an 8% reduction compared to the other tillage systems. Deltapine 1321 B2RF was consistently taller than other varieties in all years; with significant varietal differences being present during all sampling intervals each year except 2013. Fibermax 1944 GLB2 was shorter than other varieties. In‐season plant development was affected more by variety than tillage. Lint yield differed among varieties in 2013, 2014, and 2016. Deltapine 1321 B2RF produced the highest lint yields of 1746 kg ha−1, 1467 kg ha−1, and 693 kg ha−1 in 2013, 2014, and 2015, respectively. Differences in lint quality parameters were influenced more by variety than tillage system. In the short term there was no significant growth or yield penalty associated with no‐till cotton production as compared to other tillage systems. Variety selection and environment were the most important factors contributing to cotton yield during this four year study.

Impact of reduced tillage on CO2 emission from soil under maize cultivation

Carbon dioxide is an important greenhouse gas, which is released through human activities such as deforestation, burning fossil fuels, agriculture, and degradation of soil. The type of soil tillage systems has a very important impact on soil CO2 emissions. Usually higher soil CO2 emission have been observed under conventional tillage compared to reduced tillage. Maize is one of the main cereals grown around the world that reacts positively on conservation tillage. We hypothesized that reduced tillage with sub-soil fertilizer application could increase maize yield and reduce carbon emissions compared to conventional plowing. Therefore we studied CO2 emissions from soil under a conventional and innovative, environmentally safe, low-cost maize production system dedicated both to reduce time and resources and to manage the field sustainably with a lower CO2 footprint. We observed that the magnitude of grain yield depended on soil and climate conditions but not on the cultivation system. The CO2 emission level depended on the year of the study and the soil tillage method and was subject to considerable changes during the growing season. The use of reduced soil tillage significantly limited emissions of the analyzed gas into the atmosphere. Depending on the year of the study, CO2 emissions in the reduced tillage system were 7 to 35% lower than those in the conventional system. The extent of the reduction in CO2 emissions achieved under reduced tillage is very large relative to conventional tillage, which is probably due to the relatively low organic matter content of the both investigated soils in the conventional tillage. We could show that on sandy soils with a low organic matter content reduction in tillage is a factor significantly diminishing CO2 emissions.

Probabilities of having minimum amounts of available soil water at wheat planting

Winter wheat (Triticum aestivum L.)-fallow (WF) remains a prominent cropping system throughout the Central Great Plains despite documentation confirming the inefficiency of precipitation storage during the summer fallow period. Wheat yield is greatly influenced by available soil water at planting, and that quantity is influenced by cropping intensity, tillage intensity, crop grown prior to winter wheat planting, and length of the non-crop period prior to winter wheat planting. The objective of this study was to determine the effect of cropping system intensity, tillage, and crop prior to wheat planting on available soil water at planting and the probabilities of having certain minimum amounts of available soil water at wheat planting. Available soil water was measured at wheat planting for nine cropping systems varying in fallow frequency, tillage intensity, and crop prior to wheat over a 25-yr period at Akron, CO. Available soil water at wheat planting was found to be greatest (average 218 mm) for no-tillage (NT) and reduced-tillage (RT) systems in which a fallow period of 12–14 months preceded wheat planting. The lowest amounts of available soil water at wheat planting were found for the continuously cropped rotations (average 100 mm). The cumulative probability exceedance graphs of available soil water at planting fell into three groupings: 1) the five rotations that had a NT or RT fallow period prior to the next wheat crop; 2) the WF (conventional till) rotation; 3) the three rotations with either pea (Pisum sativum L.) or proso millet (Panicum miliaceum L.) prior to the next wheat crop. These graphs provide a valuable decision support tool for helping farmers assess risk in moving from a WF cropping system to a system of greater cropping intensity and diversity.

Comparison of a premix of atrazine, bicyclopyrone, mesotrione, and S-metolachlor with other preemergence herbicides for weed control and corn yield in no-tillage and reduced-tillage production systems in Nebraska, USA

A premix of atrazine, bicyclopyrone, mesotrione, and S-metolachlor (ABMS) has recently been registered for broad-spectrum weed control in corn (Zea mays L.) in the USA. The objectives of this study were to compare the efficacy of ABMS applied preemergence (PRE) with other commonly used PRE herbicides for weed control, corn injury, and yield in no-tillage (no-till) and reduced-tillage (reduced-till) corn production systems, and to determine the biologically effective doses of ABMS for controlling Palmer amaranth (Amaranthus palmeri S. Wats.) in field conditions. Field experiments were conducted in 2015 and 2016 at South Central Agricultural Laboratory, Clay Center, Nebraska, USA. ABMS applied at the labeled dose (2.89 kg ai ha−1) resulted in 92–99% Palmer amaranth control in both tillage systems. A similar level of Palmer amaranth control (86–99%) was observed with mesotrione plus rimsulfuron in the no-till system; however, the control was higher with ABMS than with other premixes in the reduced-till system at 42 days after treatment (DAT) and at harvest. Applications of ABMS at 2.89 kg ai ha−1 provided 99 and 81% control of velvetleaf (Abutilon theophrasti Medik.) and foxtail (Setaria spp.), respectively, in the no-till system at 28 DAT, whereas control was ≥93% in the reduced-till system. ABMS applied at 2.89 kg ai ha−1 resulted in 3% corn injury at 14 DAT regardless of the tillage system, whereas 15% corn injury was observed with acetochlor plus clopyralid plus flumetsulam, and dimethenamid-P plus saflufenacil in the reduced-till. ABMS or mesotrione plus rimsulfuron at labeled doses resulted in 16.0–16.3 t ha−1 corn yield, comparable to the weed-free control (16.4 t ha−1). The biologically effective doses of ABMS to provide 90% control (ED90) of Palmer amaranth at 42 DAT were 2.44 and 2.81 kg ai ha−1 in no-till and reduced-till systems, respectively. The efficacy of ABMS for broadleaf weed control and early-season grass weed control, and corn yield was the same or sometimes better than most of the PRE herbicides tested in this study; therefore, ABMS can be considered as an additional option for management of problem weeds, including Palmer amaranth in corn in the USA.

Tillage and Nitrogen Placement Effects on Yields in a Short-Season Corn/Wheat/Double-Crop Soybean Rotation

Conventional tillage resulted in greater corn yield in 2015 than with reduced tillage or no-till. A tillage × N fertilizer treatment interaction showed that N placement did not affect corn yield in conventional or reduced tillage systems, but subsurface knife N placement in no-till resulted in greater yield than when N was surfaceapplied.

Spatial Response of Near‐Surface Soil Water Contents to Newly Imposed Soil Management

Core Ideas Reports on soil water content semivariograms among soil management practices are rare. Semivariogram ranges shifted after only 2 yr of newly imposed soil practices. Findings have implications for scaling remotely sensed soil water in agriculturally mosaic areas. Near‐surface soil water content (SWC) and its spatial patterns are important for landscape hydrological responses to precipitation as well as our ability to remotely sense and model such responses. Our objective was to measure and evaluate near‐surface SWC semivariograms of agricultural fields with newly imposed (i.e., &lt;2 yr) side‐by‐side soil and residue management practices (i.e., reduced tillage systems and cover crops) in the midwestern United States. Range parameters were consistently smaller when cover crops were planted (20–25 m less) and tillage area and/or intensity was reduced (12–27 m less) compared with no cover crop and chisel plowing, respectively, except in a clayey Vertisol. Nugget and sill parameters did not have consistent trends across soil management practices or sites. These data, although brief and preliminary in scope, provide clear proof of concept that spatial pattern shifts can be clearly detected in newly imposed soil‐management systems even though differences in SWC means are not always evident.

Long‐Term Tillage on Yield and Water Use of Grain Sorghum and Winter Wheat

Core Ideas Average sorghum yield advantage was 120% for no tillage over conventional tillage and 55% for reduced tillage over conventional tillage.Average wheat yield advantage was 31% for no tillage over conventional tillage and 12% for reduced tillage over conventional tillage.Available soil water at planting in soil profile was less for conventional tillage than both no tillage and reduced tillage for both crops.There was a decline in wheat yield over time due to increased seasonal temperature. Tillage is among crop management factors that affect yield, profitability, and environmental quality. The objective of our study was to evaluate the effect of three long‐term tillage intensities; conventional tillage (CT), reduced tillage (RT), and no‐till (NT), on winter wheat (Triticum aestivum L.) and grain sorghum (Sorghum bicolor L.) yield, available soil water (ASW), and water productivity. The study was conducted near Tribune, KS, from 1991 through 2015 in a wheat–sorghum–fallow (WSF) rotation. The CT plots were tilled (primarily with a sweep plow), on average, four to five times per fallow season; NT plots used herbicides for weed control during fallow. The RT plots used a combination of herbicides and tillage for weed control during fallow prior to both crops for years 1991 to 2000; and, for the years 2001 to 2015, the RT system was NT before sorghum planting (short‐term NT) and CT before wheat planting. On average, there was a 31% wheat yield advantage for NT over CT, 16% NT over RT, and 12% RT over CT. On average, there was a 120% sorghum yield advantage for NT over CT, 41% NT over RT, and 55% RT over CT. Sorghum yields were 80% greater for continuous NT compared with short‐term NT (2001–2015 RT). The average of profile ASW at planting was less for CT compared with NT and RT. There was a significant yield and water productivity benefit in the order NT &gt; RT &gt; CT for both crops, but greater for sorghum than wheat.

Yield and Nutrient Removal in Potato‐Based Conservation Agriculture Cropping Systems in the High Altitude Andean Region of Ecuador

Core Ideas Conservation agriculture practices evaluated in this study were agronomically effective, but expensive. Reduced tillage resulted in similar yields in all crops of the potato–oat/vetch–barley–faba rotation to conventional tillage. Retaining crop and cover crops residues in the field rather than for animal fodder will make the greatest contribution to soil nutrient cycling, but likely to be the least accepted conservation agriculture practice evaluated in this study by regional farmers. The Illangama region of Ecuador's highlands is typical of much of the Andean region throughout South and Central America. Steep slopes, frequent soil disturbance and the short fallow periods threaten the sustainability of soil quality and crop production in this region. We evaluated several conservation agricultural practices, including deviation ditches, crop residue retention, and reduced tillage in the context of a potato (Solanum tuberosum L.)–oat/vetch (Avena sativa L./Vicia sativa L.)–barley (Hordeum vulgare L.)–faba bean (Vicia faba L.) rotation from 2011 to 2014 on crop productivity, crop and soil nutrient concentration, and nutrient removal from the system. Crop productivity tended to be higher in plots that had deviation ditches, and where crop and cover residues were retained in the field. Reduced tillage systems had yields similar to conventional tillage systems in all crops. Retaining crop and cover crop residues in the field had the greatest impact on recycling nutrients back to the soil, but was also the most costly conservation practice that we evaluated. Overall, conservation agricultural practices showed considerable agronomic promise for cropping systems in the Illangama region of Ecuador, but will require a longer evaluation period and a comprehensive outreach plan to help gain acceptance with regional farmers. Retaining crop and cover crops residues in the field rather than for animal fodder will make the greatest contribution to soil nutrient cycling, but likely to be the least accepted conservation agriculture (CA) practice evaluated in this study.

Sorptivity of an Inceptisol under Conventional and Reduced Tillage Practices

The amount of water captured and stored in the soil profile until the next precipitation events is of great importance in dryland agro-ecosystem for successful crop production. The soil’s ability to rapidly capture and store water precipitation can be accessed through measuring soil sorptivity. The objectives of this study were to evaluate the effects of tillage, i.e. reduced and conventional tillages, on soil sorptivity, and to understand how sorptivity is related to surface soil bulk density and water stable aggregates. The experiment was conducted on a site, which has been continuously planted with corn twice a year for more than 10 years. The predominant soil in the study site is Typic Haplusteps. Ponded infiltration measurements were used to determine soil sorptivity. Six positions, 15 meters a part, were chosen within each treatment to measure sorptivity, bulk density and water stable aggregates. Conventional tillage resulted in higher sorptivity (p&lt;0.05), lower surface bulk density (p&lt;0.05), and significantly lower water stable aggregates (p&lt;0.01) than reduced tillage treatment. Sorptivity was negatively correlated to bulk density and positively correlated to water stable aggregates. Better correlations were found between sorptivity and both bulk density (R2 = 0.67) and water stable aggregates (R2= 0.81) under reduced tillage than under conventional tillage treatment. Conventional tillage was found to enhance soil sorptivity in comparison to reduced tillage system. Appropriate soil management is important to maintain proper soil porosity in the field for better rainfall harvesting and plant growth especially in the dryland ecosystem.

Soil N&lt;sub&gt;2&lt;/sub&gt;O emissions under conventional and reduced tillage methods and maize cultivation

The study concerned the determination of nitrous oxide (N&lt;sub&gt;2&lt;/sub&gt;O) emissions under conventional and reduced tillage conditions. In the reduced cultivation, a soil cultivating seed drill was used for simultaneous sowing of seeds and subsurface application of fertilizer. The emission levels of the gas tested were dependent on the year of the study and the method of soil tillage, and were subject to considerable changes during the growing season. The use of reduced soil tillage significantly limited emissions of the analysed gas into the atmosphere. Depending on the year of the study, N&lt;sub&gt;2&lt;/sub&gt;O emission in the reduced tillage system was from 15% to 40% lower than in the conventional system. Low levels of easily mineralized components in soil could have been the cause of the reduction in N&lt;sub&gt;2&lt;/sub&gt;O emissions to the atmosphere.