Surface Application Of Lime Research Articles

Soil and Crop Effects of a Subsurface Fluid Lime Applicator

Highlights Continuous no-tillage with fertilizer deep-banded below the seed can result in stratified soil acidity that cannot be rapidly addressed with surface-applied lime. We modified a tractor-driven sweep implement to inject fluid lime that targets sub-surface soil acidity with minimal disturbance that maintains surface crop residues, and tested it prior to seeding winter peas at 4 liming rates. Soil chemistry, microbiology, and crop growth were monitored over the season. Abstract. Deep-banding ammonia and urea-based nitrogen fertilizers under continuous no-tillage can result in stratified acidification at the fertilizer-injection depth. Currently, producers address this acidification through primary tillage operations that mix the soil and dilute the acidification, but increase the hazard of soil erosion. Typically, lime is required to ameliorate soil acidity; however, surface-applied lime does not immediately address subsurface acidity, and often tillage is used to incorporate lime and correct acidified layers created through deep-banded fertilizer placement under no-tillage. Here, we designed, developed, and tested a subsurface applicator for fluid lime that can target specific soil depths and rates. The liming system was tested in Eastern Washington on a field that had been under continuous no-tillage for 25 years, had stratified soil acidity, and was to be planted to winter pea, a crop known to be sensitive to acid soil conditions. Soil pH and carbon distribution, microbial changes, biomass, and leaf area index (LAI). Results indicated that the lime targeted the seed zone and raised pH significantly; effects on biomass were marginally significant; and effects on LAI and vegetation cover were insignificant. Topography had a significant effect on all variables due to changes in applicator effectiveness with changes in soil mechanics, meaning as-applied rates varied from desired rates. Keywords: Liming, No-tillage, Precision agriculture, Soil acidity, Soil microbiology.

Long term co-application of lime and phosphogypsum increases 15 N recovery and reduces 15 N losses by modulating soil nutrient availability, crop growth and N cycle genes

In no-tillage rotation systems, the recovery of nitrogen (N) fertilizer in the soil–plant system is affected by soil fertility and biological changes caused by the surface application of lime (L) and phosphogypsum (PG). Here we assessed the effect of surface-applied L and/or PG on the fate of 15N-labeled fertilizer, soil chemical properties, microbial gene copy number (16 S rRNA of prokaryotes and genes of N cycle) and grain yield of maize (Zea mays L. intercropped with ruzigrass) in rotation with soybean [Glycine max (L.) Merrill] during two growing seasons. We found that applying L improved soil fertility, particularly when combined with PG (LPG treatment), resulting in higher grain yield. Moreover, compared with the control, the recovery of 15N-labeled ammonium sulfate [(15NH4)2SO4] increased in maize and ruzigrass dry matter but decreased in soybean grown on the residue of the first growing season in two treatments (L and LPG). The losses of 15N-labeled fertilizer were highest in the control and PG treatments. A large amount of 15N-labeled fertilizer was found in the deep layers of PG-amended soil, indicating leaching of fertilizer-derived 15N. Conversely, the analysis of soil microbial N cycle genes revealed that the abundances of denitrifiers were highest in the control (no correctives applied), suggesting that the N fertilizer remaining in the soil increased denitrification rates. Surface application of a combination of L and PG is clearly a feasible strategy for increasing soil fertility, 15N recovery from fertilizer, and grain yield while reducing environmental pollution associated with nitrification and denitrification.

Lime, phosphorus and stocking rate of an extensively managed permanent pasture affect feed-on-offer, sheep growth rate, carrying capacity and wool production

Context Soil acidity constrains pasture productivity, limiting production from grazing animals. Lime application can ameliorate acidity, although the rate is increased when incorporated rather than surface applied. Soils in south-eastern Australia are generally highly erodible, containing valuable native grasses that might be lost if disturbed. Surface application is, therefore, the only option, but the extent to which lime can ameliorate acidity and increase pasture and animal production requires research. Aim This 10-year experiment studied three rates of surface-applied lime, two of superphosphate (P) and two stocking rates (SR) on continuously grazed sheep on acidic soils. Two flocks were studied, one from May 1999 to December 2002, and the second from August 2005 to July 2008. We hypothesised that wool production and animal liveweight would increase as (1) lime rate increased, (2) P rate increased, and (3) peak animal productivity would occur under the combination of the highest rates of lime and P. Key results The experiment coincided with the Millennium Drought reducing forage production, and slowing lime movement into the soil and consequent amelioration. During Flock 1, effective SR (dry sheep equivalents (DSE)/ha) of the low P, low SR and limed treatment became higher by 1 DSE/ha for 10 months during the final flock measurement months, as drought intensified. During Flock 2, effective SR of both high P, high SR and limed treatments were greater by 2 DSE/ha than non-limed counterpart for the first 9 months of 2006. Trends of higher animal production under lime became clearer with time, so were more apparent in Flock 2 than Flock 1, and at higher SR. High lime, high P and high SR had the greatest wool production. High P, low SR and nil lime was initially highly productive, but declined sharply when legumes disappeared, associated with soil aluminium toxicity. Lime maintained superior ground cover under drought, reducing the danger of sward death and soil erosion, demonstrating its sward preservation, sustainability and ecosystem service benefits. Implications With the ever-increasing price of land, farmers must increase their land’s productivity. This trial demonstrated production and environmental benefits associated with acid soil amelioration through lime application.

Dissection of the Contributing Factors to the Variable Response of Crop Yield to Surface Applied Lime in Australia

Modern agricultural farming systems acidify the soil profile due to application of fertilisers with acidifying properties. In most parts of Australia, lime has been used to improve agricultural soil conditions and restore its productive potential. The observed response of crop yield to applied lime often varies with soil type, acidity profile and seasonal conditions, so it is difficult to specify the expected yield response in a given situation. We conducted a meta-analysis of 86 agricultural field trials from Western Australia (WA), New South Wales (NSW) and Victoria (VIC) where various rates of lime had been applied to the soil surface and crop yield (wheat, barley, canola, lupin or field pea) measured for a number of years after the initial application. Information from the meta-analysis was then paired with output from a crop simulation model, where the water-limited yield potential was estimated for both a neutral and acidified soil profile. The average increase in yield to applied lime across all locations and crops was 12%, but the response ranged from 0 to 185%. A trend was observed, where sites with topsoil pH (CaCl2) < 5 and subsoil pH < 4.5 had the greater benefit to liming. Soil type had little effect on the percentage yield increase. Overall, responses to applied lime were most likely when the yield of the trial site was at 50% of water-limited yield potential (or less), the quantity of lime applied was greater than 2.5 t ha−1 and the time since lime had been applied was greater than three years (with the maximum response occurring from four and sometimes up to eight years after liming). Therefore, soil pH measurements, combined with an assessment of actual yield relative to potential yield, provide the best guide to the response to surface applied lime and this response is likely to take more than four years to be realised.

Short- and Long-Term Effects of Lime and Gypsum Applications on Acid Soils in a Water-Limited Environment: 3. Soil Solution Chemistry

Aluminum (Al) toxicity imposes a significant limitation to crop production in South Western Australia. This paper examines the impact of surface-applied lime and gypsum on soil solution chemistry in the short term (1 year) and the long-term (10 years) in water limited environments. In the experiments, we measured soil solution chemistry using a paste extract on soil profile samples collected to a depth of 50 cm. We then used the chemical equilibrium model MINTEQ to predict the presence and relative concentrations of Al species that are toxic to root growth (Al associated with Al3+ and AlOH2 or Toxic-Al) and less non-toxic forms of Al bound with sulfate, other hydroxide species and organic matter. A feature of the soils used in the experiment is that they have a low capacity to adsorb sulfate. In the short term, despite the low amount of rainfall (279 mm), sulfate derived from the surface gypsum application is rapidly leached into the soil profile. There was no self-liming effect, as evidenced by there being no change in soil solution pH. The application of gypsum, in the short term, increased soil solution ionic strength by 524–681% in the 0–10 cm soil layer declining to 75–109% in the 30–40 cm soil layer due to an increase in soil solution sulfate and calcium concentrations. Calcium from the gypsum application displaces Al from the exchange sites to increase soil solution Al activity in the gypsum treatments by 155–233% in the short term and by 70–196% in the long term to a depth of 40 cm. However, there was no effect on Toxic-Al due to Al sulfate precipitation. In the long term, sulfate leaching from the soil profile results in a decline in soil solution ionic strength. Application of lime results in leaching of alkalinity into the soil profile leading to a decreased Toxic-Al to a depth of 30 cm in the long term, but it did not affect Toxic-Al in the short term. Combining an application of lime with gypsum had the same impact on soil solution properties as gypsum alone in the short term and as lime alone in the long term.

Short- and Long-Term Effects of Lime and Gypsum Applications on Acid Soils in a Water-Limited Environment: 2. Soil Chemical Properties

Soil acidity or aluminum (Al) toxicity is a major limitation to crop production. In this paper, we examine the effects of surface-applied lime and gypsum on soil profile chemical properties that affect Al toxicity in short-term (1 year), medium-term (2 years and 8 months) and long-term (10 years) experiments. Sulfate applied to the soil surface as gypsum was leached rapidly to a depth of 40 cm in the short-term despite relatively low amounts (279 mm) of rainfall. In the medium and long-term experiments, 28–54% of the sulfate applied as gypsum was retained in the 0–50 cm soil layer due to adsorption and precipitation reactions. The combined application of lime and gypsum increased soil calcium, to a depth of 30 cm in the short-term and to a depth of 50 cm in the medium and long-terms. Increases in soil sulfate and calcium were associated with greater electrical conductivity to a depth of 50 cm for all sampling times. Application of lime alone had no impact on soil Al, pH, and calcium in the soil layers below 10 cm in the short and medium terms. In the long-term, increasing the rate of lime application from 2 to 8 t L ha−1 increased soil pH in the 10–20 cm soil layer while soil Al decreased to a depth of 30 cm. The combined use of lime and gypsum decreased soil Al in the 30–50 cm soil layer in the medium-term and the 20–30 cm soil layer in the long-term which was more than when only lime was applied. Hence, we recommend the use of lime plus gypsum for treating soils with subsoil Al toxicity. Additionally, soil Al measurements are a more sensitive measurement of the impact of surface application lime and lime plus gypsum than soil pH.

Slow movement of alkali from surface-applied lime warrants the introduction of strategic tillage for rapid amelioration of subsurface acidity in south-western Australia

Conventional surface-application of agricultural lime takes many years to increase pH deeper in the soil profile, which is a barrier to increased adoption of liming. We conducted a series of experiments to measure the rate of vertical movement of alkali and identify the factors that determine this movement into the subsurface, to evaluate the feasibility of ameliorating acidic subsurface soil using residual (undissolved) lime (CaCO3) at Wongan Hills (30.85°S, 116.74°E) and Merredin (31.48°S, 118.21°E) and to test whether deep tillage and lime incorporation can significantly speed up the amelioration of subsurface soil acidity at Kalannie (30.42°S, 117.29°E). Multiple applications of lime to the surface of the soil at higher rates (total 6–8.5 Mg ha–1) significantly increased subsurface soil pH but only in the 0.10–0.20 m depth by 0.049 pH units per year over 10–24 years. A large proportion of the surface-applied lime was stratified in the top few centimetres of the soil and incorporation of this undissolved lime with a rotary hoe to a depth of 0.25 m significantly increased soil pH (by 0.63 units) within a year in the Wongan Hills field experiment. Deep incorporation of 6 Mg ha–1 lime to a depth of 0.45 m through excavation and spading with a small rotary hoe also increased soil pH by more than a unit and decreased Al concentration to below the toxic level within two months in the Kalannie experiment, allowing wheat (Triticum aestivum L.) plants to produce root systems up to 0.59 m deep compared with 0.26 m for the control. Our soil column leaching experiment indicated that surface incorporation of lime in higher rainfall regions can be useful to treat subsurface soil acidity but that the rate of improvement in subsurface pH was slow. Therefore, deeper incorporation of lime using cost-effective strategic deep tillage is likely to be necessary.

Impact of novel materials on alkalinity movement down acid soil profiles when combined with lime

Subsurface soil acidity in conjunction with aluminium (Al3+) toxicity is a major limitation to agricultural production globally. The conventional use of surface-applied lime is often insufficient at correcting subsurface acidity; therefore, new practices and ameliorants are required. This 3-month leaching experiment investigated whether animal wastes and other novel ameliorants in combination with lime could improve alkalinity movement, leading to greater amelioration of acid subsurface soil layers compared with lime alone. Five ameliorants (mature dairy compost, vegetable garden compost, poultry litter, potassium humate and gypsum) were added at a rate of 18 mg dry matter g−1 to the topsoil layer either without or with lime (target pH 5.5). All ameliorants with lime improved alkalinity movement below the amended layer (0–10 cm), with pH increases of 0.03–0.10 units at 1 month and 0.02–0.20 units at 3 months. In comparison, the Al3+ concentrations in 10–12-cm and 12–15-cm layers were significantly decreased by 2–5.5 μg g−1. With lime, the improvements in alkalinity movement with ameliorants were in the order of gypsum > vegetable garden compost > potassium humate > poultry litter > mature dairy compost. Without lime, each amendment increased soil pH in the subsoil, with their effectiveness decreasing in the order of poultry litter > vegetable garden compost > mature dairy compost > gypsum > potassium humate. Some organic amendments are effective in addressing subsoil acidity. When combined with lime, their additive effects are limited.

Liming and Nitrogen Fertilization Effects on Soil Microbial Community in Long Term No-till

Abstract Soil management influences organic matter decomposition rates as well soil microbial community functional behavior. No-till (NT) is the most used management system by farmers due to its conservation practices and high productivity. The main objective of this study was to evaluate the impact of surface-applied lime, nitrogen (N) application, and black oat residues on soil microbial community of a Typic Hapludox under continuous NT. Therefore, soil chemical attributes, microbial biomass carbon, basal respiration, metabolic quotient, most probable number of diazotrophs, as well as bacterial functional analysis were performed. The effect of liming and N fertilization amendments inputs were saw in soil respiration and metabolic quotient measurements, showing them to be good indicators of soil quality. Further studies should be carried out in order to molecularly identify microbial communities present in soils with different liming and N fertilization management to evaluate the behavior of specific bacterial taxa under such conditions.

Effects of lime, phosphorus and stocking rate on an extensively managed permanent pasture: botanical composition and groundcover

Low phosphorus (P) constrains productivity of many of the permanent pastures of south-eastern Australia where wool and meat production are important. Whereas the need for fertilisation with P is indisputable for many soils, the benefits of liming to ameliorate soil acidification are not always clear in terms of forage production or quality. This experiment, by measuring botanical composition and groundcover over 10 years, aimed to address the issue of forage composition and groundcover. Merino wethers were continuously grazed on a permanent pasture under two stocking rates (low and high) following treatments with three rates of surface-applied lime and two rates of P. The lime rates were: nil, and sufficient to raise the pHCaCl2 of the 0–10 cm soil layer to 5.0 and to 5.5. Phosphorus was added as two rates of single superphosphate: 125 kg ha–1 every 2–3 years, and 250 kg ha–1 every year. Two hypotheses were proposed: (i) as lime application rate increased, it would lead to the pasture swards having a higher percentage of species favourable for grazing animal production, and a higher level of sward groundcover would be maintained; and (ii) legume presence would be favoured by a higher level of applied P over the long term. The Millennium Drought (1997–2008), which coincided with this experiment (1998–2008), tended to mask or reduce lime effects; nevertheless, the higher legume content in the sward, as well as the superior groundcover found in the high lime–high P treatments at various times throughout the experiment and at its completion compared with the nil-lime control, indicated positive forage effects of lime application. Moreover, by the termination of the experiment in 2008, groundcover generally tended to be lower under nil lime than in treatments that had received lime. The higher proportion of legume in the sward was closely linked to greater applied P, although this did not occur at the low stocking rate in the absence of lime. By contrast, similar high P–low stocking rate treatments but with applied lime had the highest clover contents. It is proposed that the poor persistence of the treatment without lime may be due to a combination of poor legume seedset, because of excessive competition from accompanying grasses, and aluminium toxicity adversely affecting legume growth.

Lime and gypsum combination improves crop and forage yields and estimated meat production and revenue in a variable charge tropical soil

In tropical integrated crop-livestock under no-till (NT) systems, the surface application/reapplication of lime and/or gypsum can reduce re-acidification rate of the soil and improve plant nutrition, crop yields, and profitability. This study was conducted in the Brazilian Cerrado, which has dry winters, and aimed to evaluate the effects of surface application/reapplication of lime and/or gypsum on soil improvement, plant nutrition and crop yield improvement, as well as the forage dry matter (DM) yield, estimated meat production, and economic results. The crop rotation used between November 2004 and August 2008 was as follows: peanut (Arachis hypogaea) and white oat (Avena sativa) cultivated alone (on the first and second spring/summer and autumn/winter, respectively) and corn (Zea mays) intercropped with palisade grass [Urochloa brizantha cv. ‘Marandu’] and pasture (on the third and fourth spring/summer and autumn/winter, respectively). The experimental design was a randomized block with four replications. The treatments consisted of natural conditions of a sandy clay loam kaolinitic and thermic Typic Haplorthox (control) and the surface application of lime and/or gypsum in October 2002 and reapplication in November 2004. Surface liming was an efficient practice for increasing pH and reducing the exchangeable acidity (H + Al) and concentration of Al extending to a depth of 0.60 m. Gypsum application increased Ca2+ levels through the soil profile. Liming (with or without gypsum) had a positive effect on the nutrient acquisition by peanut, white oat, and corn crops, producing on average 48%, 52%, and 61% more pod and grain yield, respectively, than that obtained in the absence of soil amendments and with gypsum alone. The surface application of lime + gypsum also promoted forage DM yield of corn-palisade grass intercropping 22% higher than lime application and 164% higher than control; estimated meat production 26% higher than lime application and 225% higher than control, and increased economic results during four growing seasons. The surface application of lime + gypsum is an essential tool for food production in NT tropical agriculture with high soil acidity.

Effect of gypsum rates and lime with different reactivity on soil acidity and crop grain yields in a subtropical Oxisol under no-tillage

The low solubility of lime (CaCO3) and the absence of soil disturbance in fields under no-tillage (NT) may diminish the effectiveness of surface liming to reduce exchangeable Al3+ (toxic to plants) and increase the base saturation in deep soil layers. However, the effects of subsurface soil acidity can be attenuated by applying agricultural gypsum (CaSO4⋅2H2O), which is more soluble than lime, and thus, can leached bases (exchangeable Ca2+, Mg2+ and K+) and S-SO42− to deeper soil layers as well as decrease Al3+ toxicity to plants. Therefore, gypsum can be applied individually or in combination with lime. Herein, we conducted a field experiment aiming to evaluate short- (1 year) and long-term (11 years) effects of surface liming and gypsum application on the chemical properties of the 0.00–0.10, 0.10–0.20, 0.20–0.40 and 0.40–0.60 m soil layers and also on crop yield of 22 crop seasons (i.e., 10 soybean, 3 maize, 4 white oat, 3 wheat and 2 barley crops). The study was performed in a clayey Typic Hapludox of moderate acidity managed under NT for more than 25 years in Guarapuava, Paraná State, southern Brazil. Three soil surface-applied lime strategies were tested in order to raise base saturation to 70%, namely: (a) 4.62 Mg ha–1 rate of lime of low effective calcium carbonate equivalent (ECCE = 75%); (b) 3.47 Mg ha–1 rate of lime with a high ECCE value (101%); and (c) the same rate of high-ECCE lime split in three applications (i.e., 1/3 at the start of experiment; 1/3 after 1 year and 1/3 after 2 years). A control treatment without liming was also conducted. The liming strategies were combined with four rates of agricultural gypsum (i.e., 0, 3, 6 and 9 Mg ha–1) applied at the start of the experiment. Our findings did not reveal synergistic effect of lime and gypsum on soil chemical properties nor on crop yield. Gypsum resulted in very slight gains in grain yield (4% on average) and limited to just 25% of cereal (corn and winter cereals) crop seasons. On the other hand, liming increased soybean yields by 14% in 40% of crop seasons. Gypsum was more efficient than lime in raising exchangeable Ca2+ levels up to −0.60 m in the short term; however, lime promoted greater reduction of soil acidity and had a more marked residual effect on exchangeable Ca2+ contents than gypsum. The liming strategies did no promote substantial differences in crop yield, but low-ECCE lime sustained better soil chemical condition to plant growth for a longer period. Surface liming efficiently reduced subsurface acidity in a moderately acidic Oxisol managed under NT even in the short-term, promoting increments on soybean crop yields. In this case, the application of gypsum rates did not bring additional benefits to soil or plant yield.

Surface Lime Application in Long-Term No-Till Crop Production with Stratified Soil pH

Surface Lime Application in Long-Term No-Till Crop Production with Stratified Soil pH

Influence of surface lime application and seeding red clover with timothy in the old-growth stands of birdsfoot trefoil on its productive longevity

Influence of surface lime application and seeding red clover with timothy in the old-growth stands of birdsfoot trefoil on its productive longevity

Soil pH, exchangeable aluminium and legume yield responses to deep-placed lime at Omarama Station

The passive moment of lime down the soil profile in dryland is slow so a machine was developed to directly inject lime into soil, and was tested it at Omarama Station. Pelleted lime was injected at simultaneous depths of 5-10 cm and 20-25 cm below the soil surface at rates of 0 (control), 500, 1000, and 2000 kg/ha and these treatments were compared with 1000 kg/ha of surface-applied pelleted lime. The growth of lucerne, ‘Russell’ lupins and festulolium was recorded over 3 years. The deep-placed lime increased soil pH and reduced Al levels at soil depths of 25 and 30 cm, whereas for the surface-applied lime this was only the case in the top 7.5 cm of the soil. The deep-placed lime increased the growth of lucerne in the second and third years of the experiment. The lucerne was out-yielded by ‘Russell’ lupins in each year, which were unaffected by the application of lime.

Surface Application of Lime on a Guava Orchard in Production

ABSTRACT Several complications can arise, either directly or indirectly, from implementation of measures to correct soil acidity in established fruit orchards, such as impaired roots, lower root volume, risk of plant infection, propagation of diseases, promotion of pest development (especially nematodes), and soil disaggregation and compaction. These factors can have a negative effect on crop yield. Therefore, it becomes critical to implement an effective method of neutralizing soil acidity, especially at the level of the tree roots. To assess the [...]

Stratification of soil chemical and microbial properties under no-till after liming

Soils under continuous no-till (NT) often produce stratified soil acidification due to fertilizer placement and subsequent lack of mixing. Because aluminum (Al) becomes more bioavailable with lower soil pH, Al toxicity is an emerging problem in many soils throughout the Palouse region in the dryland cropping areas of the inland Pacific Northwest of the United States. When various lime materials are surface applied to NT soils, the depth to which these materials may impact soil pH, available Al, and microbial community response has not been explored in the fine-silty soils of this arid region. The objectives of the current study were to: (1) determine if soil sampling at small, discrete depth increments captures stratification of chemical and microbial properties in NT soils and (2) evaluate the impacts of two types of surface-broadcast lime on Al availability and microbial community composition at each depth interval. In April 2014 and 2015 (6 mo and 18 mo after liming), soil samples were collected at 2-cm depth increments and analyzed for soil pH and metals bioavailability, as well as microbial community composition using terminal restriction fragment length polymorphism analysis. In 2015, surface soil (0–2 cm) pH increased from 4.6 in untreated control to 6.6 in limed plots, and KCl-extractable Al decreased from approximately 50 mg kg−1 to below 10 mg kg−1 in the 2–4 cm depth of soil. The surface soil microbial community composition changed significantly in response to lime application, and was highly correlated with soil pH and Al concentrations. No significant effects of treatment were detected when data were pooled across the 10 cm depth. The 2-cm sampling increments provided statistically significant resolution in soil chemical stratification and related shifts in microbial community composition, revealing different effects at different depths. We are able to conclude from this study that (1) A finely resolved, spatially explicit sampling design is necessary to capture soil chemical stratification complexity within a variety of variables, and microbial community response over time; and (2) Surface application of lime in Palouse NT systems will take >18 mo to be effective at depths below 6 cm.

Long-term effect of surface and incorporated liming in the conversion of natural grassland to no-till system for grain production in a highly acidic sandy-loam Ultisol from South Brazilian Campos

The rate and method of lime application modify soil chemical attributes, but the re-acidification process after liming remains poorly understood in the long-term. This study aimed to assess the long-term effect of surface and incorporated liming on shifting soil use from native grassland of South Brazilian Campos to no-tillage system (NTS) for grain production in a highly acidic sandy-loam Ultisol. In 1994, an experiment in a randomized block with split plot design and four replications was installed in Southern Brazil. The main plot consisted of lime application method (surface or incorporation by soil tillage), while the subplots were lime rates (0.0, 2.0, 8.5 and 17.0 Mg ha−1), corresponding, approximately, to 0, 1/8, 1/2, and 1 fold the recommended dose to rise soil pH to 6.0 in the 0–20 cm soil layer. The 2 Mg ha‒1 treatment had reapplication every two years until soil accumulated 8 Mg ha‒1 of lime. In October 2006 and 2012 (i.e., 12 and 18 years after lime application), soil samples were collected at every centimeter from 1 to 10 cm depth, every 2.5 cm from 10 to 25 cm, every 5 cm from 25 to 50 cm and 50 to 60 cm. The chemical attributes related to soil acidity were evaluated. Even after 18 years of lime application, the re-acidification process recovered only 50% of the exchangeable Al and 30% of the potential acidity compared to native soil. Lime incorporation before NTS adoption proved to be more rapid and efficient to mitigate soil acidity than surface liming, and it is suitable for correction of deep-layered soil acidity in the soil profile. Surface lime application induced a lower alkalinization front in the soil profile, and even after 18 years there was no neutralization of total exchangeable Al in the 10–20 cm layer.

Changes in Soil Physical Properties and Carbon Protection Mechanisms by Surface Application of Lime in a Tropical No‐Tillage System

Core Ideas Liming helped avoid structural degradation. Liming effectively increased the stabilization of soil organic matter. More stable soil structure was achieved by liming. Long‐term no‐till soils often have layers that are severely affected by physical and chemical degradation. Soil acidity is associated with physical problems, such as higher bulk density, that restrict root growth and crop production, especially in tropical regions with dry seasons. Liming is the most common practice adopted to alleviate soil acidity, but limited information is available regarding the long‐term effect of lime applied superficially on soil physical attributes and the distribution of organic C in different aggregate size groups. In an Oxisol managed under a no‐tillage system for 12 yr, a trial was established with four lime rates (0, 1000, 2000, and 4000 kg ha–1) estimated using the base saturation method. The results showed that among the treatments, the rate calculated to increase the base saturation at 70% (2000 kg ha–1) provided a higher formation of water‐stable (WS) macroaggregates of >2.00 to 8.00 mm size class at 0‐ to 0.40‐m depth, and a significant decrease in the stability of the largest aggregates when the highest rate was applied. Increased values of mean weight diameter (MWD) and geometric mean diameter (GMD) were estimated with the application of rates varying from 1500 to 2500 kg ha–1. Liming increased carbon‐protection mechanisms, resulting in an accumulation of organic C in all aggregate size classes, mainly in the >0.105 to 0.25 and >0.25 to 2.00 mm size classes. Improving the formation of WS aggregates and total organic carbon (TOC) content with liming influenced positively the total porosity, macroporosity, and soil bulk density in the deepest soil layers (0.20–0.40 and 0.40–0.60 m).

Residual effect of surface-applied lime on soil acidity properties in a long-term experiment under no-till in a Southern Brazilian sandy Ultisol

The changes in soil chemical properties caused by surface lime application depend on the application dose, reaction time, and are limited to the top few centimeters of the soil profile. The present study aimed to monitor and to interpret the impacts of surface lime re-application at different rates and splitting rates on the amelioration of soil acidity and its distribution and migration through soil profile in a sandy Ultisol from Southern Brazil under long-term no-tillage (NT) system. The experiment was installed in an area where the conventional tillage (CT) was practiced till 1988 when the soil was limed (3.1Mgha−1) and then the area was maintained under NT. In October 1994, the soil was sampled and lime was reapplied at four rates: 0, 3.6, 5.4, and 6.0Mgha−1. The full dose to raise soil pH to 6.0 was applied in 1994 once. The rate of 5.4Mgha−1 was split in three times, applying 1.8Mglimeha−1 in 1994, 1995, and 1999, and the rate of 6.0Mgha−1 was split in five times, applying 1.2Mglimeha−1 in 1994, 1995, 1996, 1999, and 2000. The experimental design was randomized blocks with five replications. In October 2006 and 2012, i.e. after 18 and 24years of the start of NT or 12 and 18years after lime re-application (beginning of the experiment), soil samples were taken at each 1cm depth up to 10cm layer, each 2.5cm depth up to 10 to 25cm layer, and each 5cm depth from 25 to 60cm layer. Soil acidity attributes including active acidity (pH-H2O), aluminum (Al) saturation, exchangeable Al, exchangeable calcium (Ca), exchangeable magnesium (Mg) and base saturation were also evaluated. Results show that the re-acidification of the soil is extremely slow. Even after 24years without re-application of lime, the re-acidification process resulted in only 20% of the original potential acidity observed in the area under natural grassland. The surface application of lime in a re-acidified soil under NT promoted the formation of an alkalizing front by statistically modifying the soil acidity attributes up to 60cm. However, it was much less deeper (<35cm) when considering the agronomic interpretation of the soil acidity properties. Nevertheless, for both interpretations, the lime migration and its residual behavior were proportional to the lime application rate and its split application.