Continuous No-till Systems Research Articles

Why no-till system sequesters more carbon and is more resilient and productive with contrasting fertilization regimes in a highly weathered soil?

Land management systems that comprise the principles of conservation agriculture (CA) can lead to soil organic carbon (SOC) gains over time. Nonetheless, how fertilization regimes interfere with their performance in highly weathered soils is still uncertain. This study presents results on SOC storage, crop yield, and soil resilience from a long-term experiment in southern Brazil (Ponta Grossa – Paraná State) 26 years after its establishment in 1989 combining a gradient of soil disturbance through diverse soil management strategies with contrasting fertilization regimes. We hypothesized that preserving soil structure rebuilt over time through no-till system plays a significant role in SOC persistence and the fertilization regime can impact land management performance on soil resilience and crop yield. The experimental design was laid out as a split plot through completely randomized blocks. The main plots comprised the treatments related to soil management systems: 1) conventional plow-based tillage – CT; 2) minimum tillage (Chiselling replacing plowing) – MT; 3) no-till with one chisel plowing every three years – NTch; and 4) continuous no-till system – NTS. The sub-plots comprised full crop fertilization (FCF) for all crops and low crop fertilization (LCF) by suppressing K and P fertilization and maintaining N in broadcast application. SOC stocks significantly improved as the soil disturbance diminished, resulting in higher soil resilience indexes for NTS and NTch. Differences in SOC stocks between the contrasting treatments NTS and CT were higher under low fertilization, resulting in C and N sequestration rates of 1.14 and 0.14 Mg ha−1 year−1 under LCF compared to 0.77 and 0.08 Mg ha−1 yr−1 in FCF at the 0–100 cm layer. Such higher differences were induced by overall higher SOC stocks of CT when under FCF and higher SOC stocks in subsoil depths promoted by NTS when under LCF. High fertilization treatments produced cumulative yields 1.5 times higher for soybeans and 2.5 times higher for corn throughout the 26 years of the experiment. Labile C fractions extracted by hot water (HWEOC) and K-permanganate (POXC) were systematically increased as the disturbance diminished. Gains in labile fractions were promoted in deeper layers in lower disturbance treatments (NTch and NTS). We conclude that combining conservation agriculture principles ultimately defined the potential for SOC sequestration. The high soil resilience under the NTS in this research indicates a considerable potential to reverse the soil degradation and decline of the SOC and labile fractions by conversion to intensive NTS (high and diversified annual C input) associated with absence of soil disturbance.

Trade-offs in nutrient and sediment losses in tile drainage from no-till versus conventional till cropping systems.

Nutrient and soil loss from agricultural areas impair surface water quality globally. In the Great Lakes Region, increases in the frequency and magnitude of harmful and nuisance algal blooms in freshwater lakes have been linked to elevated phosphorus (P) losses from agricultural fields, some of which are transported via tile drainage. This study examined whether concentrations and loads of P fractions, total suspended sediments (TSS), nitrate (NO3 - ) and ammonium (NH4 + ) in tile drainage in a clay soil differed between a continuous no-till system combining cover crops and surface broadcast fertilizer (NTCC), and a more conventional tillage system with shallow tillage, fertilizer incorporation and limited use of cover crops (CT). Both sites had modest soil fertility levels. Year-round, high-frequency observations of tile drainage flow and chemistry are described over four full water years and related to management practices on the associated fields. There were similar water yields in tile drainage between the two systems; however, losses of TSS, particulate P (PP) and NO3 - were consistently greater from the CT site, which received larger quantities of fertilizer. In contrast, dissolved reactive P (DRP) losses were considerably greater from the NTCC site, offsetting the lower PP losses, such that there was little difference in TP losses between sites. Approximately 60% of the DRP losses from the NTCC site over the four years were associated with incidental losses following surface application of fertilizer in fall. This study provides insight into trade-offs in controlling losses of different nutrient fractions using different management systems. This article is protected by copyright. All rights reserved.

Preservation of labile organic compounds is the pathway for carbon storage in a 23-year continuous no-till system on a Ferralsol in southern Brazil

No-till (NT) system has the potential to sequester soil organic carbon (SOC) in the topsoil and increase soil quality. However, SOC accumulation in the soil profile and the mechanisms for SOC stabilization in NT are still a matter of debate, especially for soils of the tropics. Therefore, this study was conducted to investigate the long-term effects of two tillage systems (conventional tillage – CT and no-till – NT) on chemical and physical mechanisms of SOC stabilization and how these are related to the accumulation of SOC in the soil profile. Soils were sampled (0–100 cm depth) from a long-term experiment (23 years) established on a Rhodic Ferralsol in southern Brazil. Soils under native vegetation (NV) were used as a baseline. Results showed that conversion of NV to agriculture decreased on average the SOC stock by 70.8 Mg ha−1 (−33%) in the 0–100 cm soil layer. Between tillage systems, higher SOC stock was observed under NT than that under CT in the 0–5 and 5–10 cm soil layers, resulting in higher SOC stock in the entire topsoil (0–20 cm) in the conservation system. In the subsoil (20–100 cm), SOC was similar for both tillage systems. Fourier-transform infrared spectroscopy showed differences in the C composition between the tillage systems; an accumulation of labile compounds in the uppermost layer was observed under NT, which resulted in a lower SOM aromaticity index under this treatment than that in soil under CT management. Adoption of NT increased the proportion of large macroaggregates (> 2.0 mm) in 0–5 cm soil layer, resulting in a greater mean weight diameter (MWD) than under CT. Principal component analysis (PCA) and correlation analysis of data for 0–20 cm soil layer showed that SOC stock is positively associated with labile compounds, the proportion of large macroaggregates, and MWD, and negatively with small macroaggregates, aromatic compounds, and aromaticity index. These results indicated that the pathway for SOC accumulation in the topsoil of NT is influenced less by selective preservation but driven by the maintenance of labile organic compounds, a process achieved by the low turnover of large macroaggregates in the NT system.

Nitrogen fertilization and potassium requirement for cereal crops under a continuous no-till system

Nitrogen (N) and potassium (K) are the most required nutrients for corn and wheat production. Increasing the N application rate usually boosts crop yields. However, many uncertainties remain for K management. Potassium deficiency results in yield losses, but K application rate based on the percentage of K+ in the cation exchange capacity (CEC) is doubtful, especially in soil with high CEC. A field trial was conducted to examine the effects of KCl application before sowing corn and wheat, by raising the percentage of K+ in CEC at pH 7.0 (CECpH7.0) to approximately 2.5%, 3.5%, and 4.5%, and adding N as a topdressing (75, 150, and 225 kg ha−1 to corn and 40, 80, and 120 kg ha−1 to wheat) on the nutrition and yield of corn and wheat under a continuous no-till system (30 years). Exchangeable K+ content increased in the topsoil (0–20 cm depth) up to 7.2 mmolc dm−3 after K application at the highest rate, which, however, did not result in significant increases in nutrient uptake and yields for both corn and wheat. The N application rate positively affected the uptake and removal of all macronutrients by corn and wheat. Applying N as a topdressing increased yields of corn and wheat by up to 83% and 22%, respectively. Our results suggest that in the soil with a high CECpH7.0 (162.1 mmolc dm−3), the recommendation for K application made by considering the percentage of K+ in the CECpH7.0 may result in excessive application of K fertilizer to crops with high K-recycling potential grown under a continuous no-till system.

Strategic tillage on a Grey Vertosol after fifteen years of no-till management had no short-term impact on soil properties and agronomic productivity

Over half of the arable land in the northern grains region of Australia is managed using no-till (NT), a farming method which has improved crop yields and soil quality while reducing the input and labour costs. However, concerns have arisen among farmers over the control of weeds in continuous NT systems. An occasional targeted tillage operation (termed strategic tillage — ST) has been proposed as a management tool to reduce problem weed populations but may adversely influence soil properties and those of associated microbial communities. To assess the potential impacts of a ST operation on soil properties, a Grey Vertosol with fifteen years of NT in Northern New South Wales, Australia was tilled using either a chisel cultivator or disc chain on March 15th 2013 or on April 5th 2013. We hypothesised that ST using these minimal or low soil inversion implements at either timing would not adversely influence soil properties in the short-term (4–7weeks). The measured soil properties were soil volumetric moisture content (VMC), pH, bulk density (BD), electrical conductivity (EC), available phosphorus (P), soil organic carbon (SOC), microbial biomass carbon (MBC), metabolic activity (MA), genetic structures of bacterial communities and wheat yield (tha−1). We found that ST with either a chisel cultivator or a disc chain has great potential to assist in weed management as it did not statistically influence crop productivity or the physical, chemical and biological properties of the soil, regardless of the tillage timing.

Impact of preceding crop on alfalfa competitiveness with weeds

AbstractOrganic producers would like to include no-till practices in their farming systems, but they are concerned about managing weeds without tillage. We are seeking to develop a continuous no-till system for organic farming, based on a complex rotation that includes a 3-yr sequence of alfalfa. In this study, we evaluated impact of preceding crop on weed infestation in alfalfa. Alfalfa was established with no-till following spring wheat, corn or soybean. The study involved a 4-yr interval, with weed dynamics measured in the fourth year. Alfalfa established after soybean suppressed weeds more than alfalfa established after spring wheat or corn. Weed biomass in alfalfa following spring wheat was 18% of the plant community, but only 1% when alfalfa followed soybean and 6% when alfalfa followed corn. Weed biomass increased because alfalfa density following spring wheat was only 71% of alfalfa following soybean. Weeds such as downy brome (Bromus tectorumL.) and dandelion (Taraxacum officinaleWeber) were able to establish and produce biomass where alfalfa stand was sparse. Alfalfa forage yield across 3 yr was also higher following soybean than either spring wheat or corn. Alfalfa competitiveness with weeds can be improved by choice of preceding crop.

Surface liming and nitrogen fertilization for crop grain production under no-till management in Brazil

Supplying a large amount of NO3− in the subsurface can be a strategy to combat subsoil acidity under no-till systems. However, soil acidification caused by ammoniacal fertilizers can increase both aluminum toxicity and lime requirement. A field experiment was performed in the period from 2004 to 2012 in Parana State, Brazil, on a loamy, kaolinitic, thermic Typic Hapludox to evaluate the effects of surface liming and ammoniacal fertilization on soil chemical attributes and yields of crops in rotation under continuous no-till. The region has a mesothermal, humid subtropical climate, with mild summer, frequent frosts during the winter, and no defined dry season. The average altitude is 970m and the annual precipitation is about 1550mm. The treatments consisted of annual applications of NH4NO3 at 0, 60, 120, and 180kgNha−1 to subplots within plots with surface-applied lime previously at 0, 4, 8, and 12Mgha−1, calculated to raise the base saturation in the topsoil (0–20cm) to 40, 65, and 90%. Lime was broadcast on the soil surface in May 2004. The nitrogen rates were applied during the period from 2004 to 2011 in top dressing at tillering of winter crops [black oat (Avena strigosa Schreb.) or wheat (Triticum aestivum L.)], before growing corn (Zea mays L.), soybean (Glycine max L. Merr.) or bean (Phaseolus vulgaris L.) during the summer (2004–2012).Surface-applied lime under no-till was effective in alleviating soil acidity from the soil surface to a 20cm depth. The soil pH increased in the layers below the soil surface to 20cm depth during a 6 years period following surface lime application. Ammoniacal fertilization had an acidifying effect and did not change the effectiveness of surface applied lime to alleviate subsoil acidity. Soil organic matter content was higher in the upper few centimeters under no-till and remained unchanged over time after surface liming and ammoniacal fertilization. Increasing the rate and frequency of ammoniacal fertilizer application increased crop response to surface liming, but did not change the lime requirement to achieve higher crop grain yields. The lime rate estimated by the soil base saturation method at 70% in the 0–20cm depth was appropriate for surface liming recommendation, even when substantial amounts of ammoniacal fertilizer were applied in a no-till system. The results suggest that nitrogen fertilizer use for winter crops could be dramatically reduced in areas under a continuous no-till system, particularly where lime has been applied.

Soil Structural Disturbance Effects on Crop Yields and Soil Properties in a No‐Till Production System

The development of well‐structured soils is a goal for achieving sustainable and productive agricultural systems. Nevertheless, the maintenance of soil structure in continuous no‐till (NT) soils has sometimes been thought to induce soil conditions that are detrimental to crop yields. The objectives of this research were to characterize the effects of periodic tillage disruption in otherwise NT systems on soil properties and the yields of winter wheat (Triticum aestivum L.), double‐cropped soybean [Glycine max (L.) Merr.], and maize (Zea mays L.) in rotation and to determine if soil structural changes occurring in tilled soils are independent of changes in other soil properties. A field experiment was established in 1992 on a Huntington silt loam soil (Fluventic Hapludoll) at the University of Kentucky Research and Education Center in Princeton (KY) under a NT crop sequence with two seedbed preparation methods for winter wheat, (a) NT or (b) chisel plus disk tillage (Till). In fall 2000, similar soil chemical properties were observed between disrupted and continuous NT systems over the 0‐ to 20‐cm layer. The geometric mean diameter of dry fragments and the soil water content retained between 0.0003 and 0.03 MPa water potential was greater in NT soils than in soils tilled for winter wheat. Tillage for winter wheat enhanced winter wheat yields (4.2% increase), mostly under low‐yielding conditions, but it resulted in a reduction of subsequent summer crop yields (i.e., 3.7% for soybean and 7.0% for maize). The yields obtained in our study translate to an economic benefit for the continuous NT system. Net returns per hectare were estimated to be $73 higher for the winter wheat/double‐crop soybean–maize rotation under NT than under Till treatments. The differences in maize yields between NT and tilled treatments were attributed to a better water supply in NT soil due to the maintenance of a larger number of mesopores and a great hydraulic conductivity. In the absence of significant changes in other physicochemical properties, periodic tillage appears to disrupt soil structure, which negatively affects crop productivity.

Effect of soil texture, organic carbon and water retention on the compactability of soils from the Argentinean pampas

The Mollisols from the Pampas Region of Argentina have been described as presenting different compactability behaviors under agricultural systems. The purpose of this study was to provide information on the inherent soil factors related to the susceptibility to compaction. Total organic carbon (TOC), texture (CLAY, SILT, SAND), water retention at 0.33 kPa (WR), Proctor maximum bulk density (BD MAX) and critical water content (CWC) were determined for 26 top-soils selected from the semiarid, subhumid and humid Pampas Region. The selected sites crossed three soil textures (loamy sand, loam and silty loam). It was observed that the compactabilty of these soils could be assessed by inherent properties routinely measured in the laboratory. Their behavior under experimental compaction revealed that TOC had a dominant effect on the susceptibility of these soils to compaction. Higher TOC levels reduced the BD MAX ( r 2=0.75, p<0.01) and the CWC ( r 2=0.82, p<0.01), independently of textural class. The increase in BD MAX per unit of water content (susceptibility to compaction, SC) depends on SILT and TOC levels ( r 2=0.49, p<0.01). Although the BD MAX levels were lower than those considered critical for rooting and diminished with increasing TOC, water and SILT contents, in addition to TOC, can determine the potential for compaction in these soils. Based on the need to prevent shallow compaction, continuous no-till systems are possible on soils from the semiarid Pampas Region but not in soils from the subhumid and humid Pampas Region with low TOC.

Long Term Tillage Effects on Grain Yield and Soil Properties in a Soybean/Grain Sorghum Rotation

In Nebraska, early adopters of conservation tillage, especially those using no-till planting, had some concerns regarding planter performance, early season weed control, and possible yield reductions. Selected tillage and planting systems were used long term to evaluate effects on soybean [Glycine max (L.) Merr.] and grain sorghum [Sorghum bicolor (L.) Moench] yield, soil properties, and residue cover in a nonirrigated rotation. The six tillage and planting systems selected for evaluation were: no-tilI, no-till with row-crop cultivation, disk, double disk, chisel, and plow. In 1981, two sets of field plots were established near Lincoln, NE, on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls) so that both crops could be evaluated each year