Correct Soil Acidity Research Articles

Deep tilling and localized liming improve soil chemical fertility and sugarcane yield in clayey soils

The selection of an appropriate soil tillage system for improving yields and longevity is an important decision in sugarcane cultivation. In the present study, the effects of different soil tillage systems and methods of applying lime on sugarcane stalk and sugar yield performance as well as soil fertility parameters were evaluated throughout the sugarcane crop cycle. The experiments were established in two locations in April 2015 and conducted until August 2019, corresponding to a total of 4 growing seasons. A field study with a randomized block design was established with four replicates considering 4 treatments: conventional soil tillage system (CT), deep strip-tillage system (DT) and modified deep strip-tillage system (MDT), all with the same lime rate; and a standard treatment (control, CT without liming). Immediately after harvesting plant cane (18 months (mo) after planting), first ratoon (30 mo after planting), second ratoon (42 mo after planting) and third ratoon (54 mo after planting), soil samples were collected from a depth of 0.0–1.00 m, stratified every 0.2 m. Leaf material was sampled during the period of full vegetative growth. Analyses of soil chemical fertility, leaf concentrations of elements, and sugarcane yield components were performed. MDT was found to correct soil acidity most efficiently, mainly due to the positioning of the lime application. Under high aluminum saturation (AS), especially in deeper layers, deep lime placement was more effective and resulted in the best distributions of calcium (Ca2+) and magnesium (Mg2+), the highest base saturation (BS) and the lowest AS compared with the other treatments. Lime application was more important than the tillage system for improving the sucrose concertation and total recoverable sugar (TRS), whereas the tillage system affected the stalk yield and, consequently, the yield of sugar. Compared with DT and CT, the average stalk yield was 4.1% and 9.4% higher, respectively, under MDT at Macatuba and 6.3% and 15.3%, higher, respectively, under MDT at Piraju. Similarly, MDT improved average sugar yield by 3.7% and 10.4% at Macatuba and 6.1% and 16.3% at Piraju. Overall, long-term assessments, which are important for semi-perennial crops like sugarcane, showed that the both deep strip-tillage were most effective.

Soil acidity and soy phytometry under application of limestone and agricultural gypsum

The soybean is one of the main agricultural crops in Brazil, because the use of its grains is an important source of protein and vegetable oil. One of the main limiting factors for obtaining high yields in soybean in tropical soils is related to the need to correct soil acidity. The objective of this study was to evaluate the growth of (Glycine max (L.) Merrill) and the variation of soil pH values under the application of limestone and agricultural gypsum. The experimental design was completely randomized, distributed in a 4x4 factorial scheme. The treatments consisted of doses of 0, 1.5, 3.0 and 4.5 t ha-1 of only limestone, only gypsum and the combination of limestone and gypsum, repeated four times, totaling 64 experimental units. The soil pH was evaluated at 30, 45, 60, 75 days before sowing. The growth variables were: number of pods, shoot dry mass, root dry mass, root length and shoot/root ratio. The variables pH 75 days, root length and shoot/root ratio were significantly influenced by the treatments, alone or in interaction. For pH 30, pH 45 and pH 60 days, number of pods and shoot dry mass, there were isolated effects of treatments for gypsum and limestone. In root dry mass, the effect of the treatment was verified only with the use of limestone. As a conclusion, the application of limestone and gypsum reduces the soil acidity, obtaining higher pH values from the doses of 3000 kg ha-1, with the combination of limestone and gypsum. The use of gypsum consortium with limestone promotes significant results in the growth of soybean plants.

Assessment of suitable dose of calcium silicate to rice and its impact on soil properties in laterite soils of Odisha

A field experiment was conducted in the central farm, Regional Research and Technology Transfer Station, Coastal Zone OUAT, Bhubaneswar during kharif 2020 using cv-Lalat variety of rice. The experiment was laid out in randomized block design (RBD) with ten treatments and three replications. In this experiment, Basic Oxygen Furnace (BOF) slag was used as a source of silica for application in rice crop. 200, 300 and 400 kg SiO2ha-1 was applied in combination with 50% Soil Test Dose (STD) and 75% STD in order to assess the efficacy of Silica with reduction in fertilizer dose by 50% and 25%. The result indicated that there was significant increase in number of effective tillers per plant and length of the panicle, but no significant increase was observed in case of 1000 grain weight over control. In case of grain yield, straw yield and harvest index, 100% STD registered maximum (36.9q/ha) grain yield which was 29.4% more than that of control. In case of 50% or 75% STD with 300kg SiO2ha-1 grain yield was at par with 100% STD, which indicated that silica application has the capability to reduce the fertilizer dose. Harvest index was not significantly affected by Si treatments. However, maximum HI (0.478) was observed in 75% STD + 300 kg SiO2ha-1. The present study showed increase in pH and organic carbon content in post-harvest soil which suggests that application of silica has the capacity to correct soil acidity and improve soil organic carbon in acidic laterite soils.

The short-term effects of surface-applied dolomitic lime and gypsum on soil chemical properties and yields of sugarcane ratoon crops in KwaZulu-Natal, South Africa

This study investigated the effects of surface-application of lime and gypsum on soil properties and yields of ratoon sugarcane crops. Treatments involved once-off surface application of dolomitic lime (L), gypsum (G) and dolomitic lime plus gypsum (LG) in factorial combination, with four replications. Soil chemical properties were measured on samples collected at intervals of 20 between depths of 0 and 80 cm in the first and fifth years after treatment application. Yield parameters were measured annually. In the first year, treatment effects were mainly restricted to a depth of 0–20 cm. The LG increased pH(CaCl2) from 3.9 to 4.5, and calcium from 123 to 350 mg L−1. Little treatment effect was observed on yield parameters in the first year. In the fifth year, L and LG generally showed similar impacts on soil properties. The L treatment led to markedly increased pH(CaCl2) and calcium and somewhat decreased magnesium levels in the topsoil. The sucrose and cane yields in LG were significantly higher than in other treatments, which all had similar results. It was, therefore, concluded that LG may be a viable option for the correction of soil acidity through surface application in the sugarcane ratoon crops grown in the sandy soils of KwaZulu-Natal.

Limestone and Silicate Applications by Different Methods to Correct Soil Acidity

The study aimed to measure the variation in the values of pH, P, K, Ca, Mg, Al, H+Al, V, and Ca and Mg saturation after limestone and silicate applications as a function of different soil correction methods and incubation periods under a controlled environment. The research was carried out in a greenhouse at the FCA of the Federal University of Grande Dourados (UFGD). The experiment was completely randomized in a factorial scheme (5 × 3 × 5), with four replications. The main factors consisted of five incubation times: 0, 30, 60, 90, and 120 days; three soil classes: dystrophic Red Latosol (LVd), Dystroferric Red Latosol (LVdf), and dystrophic Gray Argisol (PACd); and five soil acidity correction methods: control, Ca/Mg balance for limestone and silicate, and 50% and 70% base saturation. Chemical analysses were performed after each incubation period. A regression analysis was carried out once a significant difference was observed between the means of the main factors of the analysis of variance, being adjusted to quadratic models for pH, P, Al, K, Ca, Mg, H+Al, and V. Statistical analyses were performed in the AgroStat software. The ideal soil incubation time to reach the maximum efficiency of correction of the chemical attributes of LVd, LVdf, and PACd soils by the studied methods ranges from 78 to 86 days. The application of limestone by balance of 60% Ca and 20% Mg and calcium and magnesium silicates achieved the best correction indexes of soil chemical attributes, enabling the proposed equation as a calcium and magnesium silicate calculation.

Exploring the synergism between surface liming and nitrogen fertilization in no‐till system

AbstractSurface liming to correct soil acidity may have limited effectiveness in subsurface layers in no‐till systems (NTS). The possibility of downward movement may be increased when liming is combined with fertilization with urea (ammoniacal N), as NO3– formed by nitrification of NH4+ can form ion pairs with exchangeable Ca2+ and Mg2+. Liming can also increase the nitrogen use efficiency (NUE) of crops and reduce dependence on soil N. In this work, we investigated the effects of surface application of lime under NTS and N topdressing on soil chemical properties and the nutrition, productivity, and NUE of maize (Zea mays L.) and upland rice (Oryza sativa L.). The treatments comprised four lime rates applied superficially (0, 1,500, 3,000, and 6,000 kg ha–1), and absence (–N) or presence of N fertilization (+N) as urea by topdressing. The treatments were applied during two agricultural years (2011/2012 and 2012/2013), with maize in the first crop season and upland rice in the second crop season. At 18 mo after liming, the application of 6,000 kg lime ha–1 significantly improved the chemical attributes of the soil (pH, soil organic matter (SOM), K, Ca2+, Mg2+, and base saturation [BS]). The application of urea increased the mobility of Ca2+ and Mg2+ to greater depths. The combination of 3,000 kg lime ha–1 with N fertilization synergistically increased the nutrition (N, P, and S), grain yield, and N‐related efficiency indexes in the maize and upland rice crops.

Physiological, biochemical and nutritional changes in soybean in response to application of steel slag

Steel slag is a powdery industrial residue that has CaO, MgO and SiO2 in its composition, which enables its use in agriculture for soil acidity correction. Most studies involving this residue have focused on understanding its effects on the soil, not always considering its action on the plant metabolism. Thus, the present study aimed to evaluate physiological, biochemical and nutritional changes in soybean plants due to application of lime and steel slag on the soil surface or by incorporation. The experiment was carried out in the field, with six soil acidity corrective materials: stainless steel slag, steel slag, ladle slag, wollastonite rock, dolomitic lime and calcined dolomite, plus a negative control, which did not receive correctives. Two application methods were adopted: soil surface application or incorporation. Sixty days after application, the soybean crop was established. Soybean response changed with the application method, since incorporation of corrective materials provided greater production of fresh and dry leaf mass and stem fresh mass, increased chlorophyll b and leaf K levels, and contributed to a greater number of plants per hectare and pods per plant, compared to surface application. Besides such benefits, there was no difference between the effect of application methods on soybean yield, indicating that both incorporation and surface application are efficient in increasing soybean grain yield. The correctives steel slag, wollastonite and calcined dolomite provided significant increases in soybean yield

Correction of Soil Acidity in an Organic System of Shadowed Coffee

Through sustainable agriculture it is possible to explore the coffee culture in consortium with native forests in more rugged reliefs, as coffee is a permanent crop in addition to the climatic conditions offered by the swamps that favor its development. Given the above, the present work proposes, based on the acidity results, to quantify the need for correctives in the soil to obtain a better nutritional use offered by agroforestry cultivation of organic coffee in the shade with favorable results to increase productivity and, consequently, the farmer's profit. The research was carried out at the Várzea da Onça farm, in the Yaguara Ecological Complex, located in the municipality of Taquaritinga do Norte, Borborema plateau, in the Agreste Pernambuco mesoregion. Altitude, it is necessary to adopt appropriate management techniques that guarantee production, soil conservation and biodiversity, proposing soil correction to guarantee the ideal nutritional conditions for coffee growth. For this purpose, soil samples were collected in the Top (T), Hillside (E) and Pedimento (P) ranges at depths of 0-20, 20-40 and 40-60 cm when planting shaded coffee and soil samples from Native Forest (MN) preserved and legally protected from the Brejo de Taquaritinga. Active, exchangeable and potential acidity were analyzed, as well as the sum of bases, the potential and effective cation exchange capacity, base saturation and aluminum saturation. The results obtained were subjected to analysis of variance and the means were tested at 5% by the Tukey test. A potential of the system was found with low to very low natural fertility, with a strongly acidic reaction. Thus, adequate soil management and correction techniques are necessary for the crop to absorb all the nutrients made available by the organic matter present on the surface, concluding that all slopes require liming, the slope of Hillside and Mata Nativa they also need plastering for the culture to develop properly.

Crop yields in no-tillage are severely limited by low availability of P and high acidity of the soil in depth

The combination of high aluminium (Al) saturation and severe phosphorus (P) deficiency in sub-surface soil in no-tillage (NT) systems is an obstacle hampering crop yields in Brazil. The introduction of NT without proper soil chemical correction affects crop yields in several parts of the country. The aim of this study was to evaluate the changes in soil chemical properties and response of crops to different application methods of lime and phosphate fertiliser in an Ultisol under NT. The field experiment consisted of combining surface and incorporated liming and P application (without P, surface P and P in the sowing line), plus a treatment with incorporated lime and P. The correction of soil acidity and availability of P at depth was effective with the incorporation of lime and phosphate fertiliser. Five months after lime incorporation, it was possible to increase soybean productivity by more than 40% (from 3.9 to 5.6 Mg ha−1). The surface application of P and limestone restricts the correction of soil fertility only in the uppermost soil layer evaluated (up to 5 cm). The relationship between soybean yield and soil chemical properties in different layers clearly demonstrates that neither the 0–10 cm soil layer nor the 0–20 cm soil layer is suitable for diagnosing soil fertility and the crop productive potential in NT system with chemical restrictions in subsurface. Further studies are need to establish critical levels of available P and Al saturation for subsurface soil layers in different soil types under no-tillage.

Application Technology in the use of Correctives in Corn Culture

Corn is one of the most cultivated cereals in the world and is used for various purposes and its production is linked to its economic importance, requiring the use of means and methods that enable the increase of its production and one of them is the correction of the ground. The objective of this work is to carry out a brief literature review on the application technology in the use of correctives in the corn crop, highlighting the benefits of its use and the need for its use in the crop. The present study was developed based on a literature review and relevant research on the technology of application of correctives in corn crop, highlighting the benefits of its use and the need for its use in corn crop. Agriculture went through a long development, improving its production system and application technology came with one of the alternatives helping to maintain and improve soil quality, enabling the application of correctives in the soil with greater efficiency. The need for soil correction has to do with the relationship between the plant and the soil, highlighting the acidity, which in many cases is a problem for the cultivation of crops. The use of correctives to correct soil acidity brings many benefits to the physical and chemical characteristics of the soil, reduces fertilizer losses caused by leaching, provides calcium and magnesium to the soil adjusting the soil profile so that plants can benefit from available nutrients. Thus, application technology is essential for the corn crop and for the entire production system, even more in the application of correctives, as acidity is one of the causes of yield limitations. Thus, application technology favors soil correction, ensuring the benefits provided by proper application, becoming a means of increasing crop productivity and corn as well, due to the various productive aspects provided by the correct application in the soil.

Fermentation profile and chemical composition of cassava root silage

ABSTRACT The use of cassava root silage for animal feeding is a suitable option for farmers who grow cassava as an alternative product and for cattle ranchers who have to deal with high prices of corn. Our objective was to determine the effects of cassava genotypes and the correction of soil acidity on the microbial population, fermentation characteristics, chemical composition, aerobic stability and losses of cassava root silage. We used a 2 × 3 factorial design in completely randomized blocks, with four replications. We evaluated two cassava genotypes (Caeté and Manteiguinha) and three methods of soil acidity correction (lime, gypsum, and lime+gypsum). The roots were harvested 11 months after planting, ensiled in PVC silos, and stored for 45 days. No interaction was observed between genotypes and soil acidity correction for any of the evaluated parameters. The silage of Caeté genotype showed the highest concentration of dry matter (421 g kg-1 fresh matter) and non-fibrous carbohydrates (893 g kg-1 dry matter), and the lowest concentrations of neutral detergent fiber (37.1 g kg-1 dry matter) . No significant differences were observed among treatments for lactic acid bacteria, yeast and mold counts in silages. Both genotypes resulted in silages with an adequate fermentation profile and considerably high aerobic stability, but with high effluent loss. The Caeté genotype showed to be potentially better for silage production due to its higher dry matter recovery. Due to the high level of effluent loss, it is recommended to test the effect of a moisture-absorbing additive during the ensiling process of these cassava roots.

Multivariate analysis of chemical attributes of an oxisoil under Saccharum spp. and Pinus spp., Batatais, São Paulo

This study aims investigate the correlations of soil chemical attributes in watersheds in order to highlight the changes caused by soil management, differentiating them by multivariate statistical analysis. The watersheds of the first order of magnitude were selected three occupied with sugarcane, three with the Pinus reforestation and a witness with greater occupation of native forest. The composite samples of soil were collected at five points around each major source in depth 0-0,2 m, on two occasions (April and December). The first two factors aggregated 58.09% of the total variance of the initial data (F1 = 44.80%; F2 = 13.29%). The first factor shows a direct correlation between the pH, Ca, Mg, SB and V variables, which are inversely correlation with H+Al and Al variables, showing the process of soil acidity correction (lime) in the occupied watersheds with sugarcane crop. The second factor show a direct correlation between the T, OM and Cu variables, indicating high soil acidity in reforestation of Pinus. The multivariate analyses show the change of the agroecosystem of watersheds studied as a function of soil management.

Limestone and gypsum reapplication in an oxisol under no-tillage promotes low soybean and corn yield increase under tropical conditions

Limestone and gypsum combined use in no-tillage (NT) systems can favor soil acidity correction and improve nutrient availability in-depth with positive effects on crop production. There are still doubts about the necessity to restart the NT when the soil’s natural acidity was not corrected properly. The study evaluated i) the changes in the vertical distribution of nutrients and the acidity attributes in the soil solid phase, ii) the crop yields resulting from limestone reapplication strategies, associated or not with superficial gypsum application, and iii) the need to restart the NT system, with limestone incorporation to correct the re-acidification of an Oxisol in the Cerrado biome. Six treatments were evaluated, following the NT maintenance: i) no limestone reapplication and no gypsum application (NL), ii) superficial gypsum application (NL+), iii) superficial limestone reapplication (SL), and iv) superficial limestone reapplication and superficial gypsum application (SL+); or restarting the NT: v) limestone reapplication and incorporation (IL), and vi) limestone reapplication and incorporation followed by superficial gypsum application (IL+). Seven years after the experiment implementation, the soil was sampled in eight stratified layers down to the 50 cm depth in the experimental plots and under the Cerrado natural vegetation (CNV). The chemical attributes related to soil acidity, nutrient availability, and the soybean and corn yields were evaluated. The soil under CNV has lower pH and greater aluminum saturation (Alsat) than the NL treatment, whose natural potential acidity was corrected 36 years ago and remained without limestone reapplication for 11 years. Such results indicate that the soil re-acidification process is slow. Superficial limestone reapplication (SL and SL+) reduced soil Alsat down to 25 cm but did not neutralize it completely. Limestone incorporation (IL and IL+) had little effect on Alsat distribution in-depth when compared to superficial limestone application. Gypsum application increased Ca content and lead to Mg displacement in soil depth, but did not affect Al dynamics, nor the crop yields. The effects of limestone and gypsum reapplication on the soil surface under NT provided a greater nutrient accumulation in the soil superficial layer, especially Ca and Mg. Soybean showed a low but positive yield response to the limestone reapplication, regardless of the method (average yield increase of 252 kg ha−1 year−1), but corn yield was less affected. There is no need to incorporate the limestone neither to apply gypsum in agricultural lands that had their natural acidity corrected properly in the past.

Crescimento e produção de matéria seca de raiz e parte aérea em mudas de Poncirus trifoliata (L.) Raf. sob efeitos da gessagem e calagem

A qualidade da formação dos pomares de citros está diretamente relacionada ao porta-enxerto utilizado. A espécie Poncirus trifoliata (L.) Raf., conhecida como trifoliata, tem-se mostrado como boa opção de porta-enxerto, sendo usada na região Sul do Brasil. O calcário e o gesso agrícola são os principais insumos usados para manejar a acidez do solo em superfície e subsuperfície, respectivamente, podendo melhorar o desenvolvimento de raízes e parte aérea das plantas. Objetivou-se avaliar o crescimento e produção de matéria seca de raízes e parte aérea em mudas de trifoliata cultivadas sob efeitos da gessagem e calagem. As mudas foram cultivadas em colunas de tubo de PVC (vasos), com 15 cm de diâmetro e 35 cm de altura, seccionadas em dois anéis: o anel superior, 0-15 cm de profundidade, e o anel inferior, 15-35 cm de profundidade. O experimento foi realizado em esquema fatorial (2×4)+1, sendo dois tratamentos de calagem e quatro tratamentos de doses de gesso agrícola, que foram aplicados apenas no solo do anel superior, e um tratamento adicional que recebeu calagem no solo de ambos os anéis, superior e inferior. O delineamento experimental foi em blocos ao acaso com quatros repetições. A calagem e as doses de gesso não afetaram o desenvolvimento da parte aérea das mudas de trifoliata, porém houve maior teor de clorofila aos 55 dias após transplantio com a gessagem sem a calagem. A calagem aumentou a produção de matéria seca de raiz na camada superficial do solo (0-15 cm de profundidade), mostrando a importância da correção da acidez do solo para o desenvolvimento do sistema radicular em mudas de trifoliata.

Preliminary analysis of steelworks residues and their application in a sandy soil

The steel residues application (SR) in sandy soils, under a proper handling management, can result in a benefits range, among which, the soil acidity correction. This study investigated the gralunometric composition of three slags and one exhaustion powder from a steel mill, in the municipality of Marabá-PA, in addition to the ability of soil pH correction. To identify the granulometric fractions were used number 8, 10, 16 and 18 mesh sieves. The pH correction experiment were made in factorial scheme, evaluated 3 doses of each RS (1.5 t ha-1, 2.0 t ha-1 and 2.5 t ha-1) in vases with Neosol, for 60 days. Residues from the steel refining (EAFS, LDS and EAFD) showed a particle size predominantly under 1.00 mm, and promoted pH values above to 7.0. The blast furnace slag obtained domain of particle sizes > 2.00 mm, with 77% of the material retained in the sieves, and their soil disposition promoted similar results to dolomitic limestone, used traditionally to pH correction in acid soils, representing an alternative in soil preparation. Others residues also showed the soil pH correction capacity, although the used dosages proved to be above the ideal, with values above 7 and alkalinity tendency. The necessity of an investigation of EAFS, LDS and EAFD residues dosage are essential to pH soil correction, in order to condition the soil to pH ranges considered ideals (6-6.5).

Delineating the nutrient constraints and developing nutrient norms for cashew (Anacardium occidentale L.) in coastal India

Sub-optimal productivity in cashew is common in tropical India due to inadequate attention on plant nutrient management. Identifying the nutrient constraints, its diagnosis and management are important for maximizing production in a sustainable manner. We established nutrient diagnostic norms for cashew that shall be useful for quick diagnosis of the nutrient requirement of cashew for devising rapid nutrient management schedule to improve the productivity. The optimal leaf nutrient status in cashew for nitrogen, phosphorus, potassium, calcium, magnesium and sulfur ranged from 2.23 to 2.82, 0.13 to 0.18, 0.91 to 1.47, 0.92 to 1.39, 0.46 to 0.70 and 0.75 to 1.14% respectively. The optimal leaf status for micronutrients such as iron, manganese, zinc, copper, boron and molybdenum ranged as 285 to 398, 200 to 409, 54 to 74, 47 to 60, 22 to 46 and 3.0 to 4.4 mg kg−1. The regional survey on soil and leaf nutrient status of cashew in prominent cashew growing areas along coastal India revealed the nutrient constraints causing lower productivity levels. The cashew growing soils in India were predominantly deficient in nitrogen, potassium, calcium, magnesium, zinc and copper. The study indicated the ill effects of neglect of fertilizer and manure application in cashew on soil organic carbon, nitrogen and potassium, which adversely affected the nutrient uptake by cashew as evident from the leaf nutrient status. The study also highlighted the need to pay attention to soil ameliorants to correct soil acidity to make available calcium, magnesium and micronutrients such as zinc, copper and manganese.

Effect of Soil Compaction and Application of Lime and Gypsum on Soil Properties and Yield of Soybean

ABSTRACT Lime and gypsum application is one strategy for correcting soil acidity and improving soil fertility. However, soil compaction in no-till systems can influence these dynamics. This study aimed to assess the effect of lime and gypsum application under different soil compaction levels on soybean yield and soil chemical attributes. The application of lime and gypsum under artificial compaction levels and the movement of exchangeable calcium (Ca2+), magnesium (Mg2+), potassium (K+), and soil pH were monitored in the 0–0.05, 0.05–0.10, 0.10–0.20, and 0.20–0.40 m soil layer depths. Soybean grain yield was not influenced by the gypsum and lime applications and artificial compaction levels. In the 0.05–0.1, 0.1–0.2, and 0.2–0.4 m soil layers, the exclusive surface application of lime was effective in increasing the soil pH. Ca2+ and Mg2+ carbonates had low solubility and mobility in the soil; however, a rapid reaction to the surface over a relatively short period was observed. K+ concentration in the 0–0.05 m soil layer did not vary after the gypsum and lime applications. Therefore, the superficial application of lime is effective in acidity correction in no-till systems when the soil is not compacted.

Comparison between Limestone and Silicate Corrective Associated Gypsum in the Growth of a Forage Grass

ABSTRACT Soil acidity is one of the most limiting factors in crop yield. We evaluated the effect of soil acidity correction with magnesium limestone and calcium (Ca) and magnesium (Mg) silicate associated gypsum application, on the growth of a forage grass. The experiment was conducted in a greenhouse with a soil sample from B horizon of a Rhodic Hapludox. The experimental, design was completely randomized blocks with seven treatments each replicated four times. Two sources of amendments (magnesium limestone and calcium and magnesium silicate) were incorporated in a surface (0 to 0.20 m) soil sample using three application methods: amendment without gypsum, amendment with gypsum incorporated in the sample, amendment with superficial application of gypsum, and a control treatment without amendment and gypsum. The limestone and silicate were effective in correcting acidity and increasing exchangeable soil bases in the 0.20 m layer. The use of acidity correctors combined with gypsum, mainly incorporated, neutralized toxic aluminum and increased the levels of sulfate and Ca in depth and the concentrations of Ca, Mg, nitrogen and phosphorus in dry weight of the shoot (DWS). The silicate increased the concentrations of silicon (Si) the soil up to 0.20 m depth and Si concentration in the plant. The silicate with gypsum provided greater production of DWS, while limestone with gypsum increased the production of dry weight of roots the plant. The application of silicate in complement to limestone, combined with incorporated gypsum is the most suitable method for soil correction in the implantation of mombaça grass.

Correction of soil acidity with shell lime and dolomitic limestone in a Latossolo Vermelho distrófico in Paraná state, Brazil

Soil acidity is a limiting factor for agricultural production, and the correction is carried out by liming, with the variable response with characteristics of the soil and the source used. The study aimed to analyze the effect of liming on a Latossolo Vermelho distrófico (stands for the oxisols in soil taxonomy and Ferralsols in WRB-FAO). The experiment was conducted in a completely randomized design in a 2x2x3 factorial scheme, with two soil textures (medium and clayey), two types of limestone (dolomitic and shell), and three soil cover conditions (without cover, with corn residues, and with soy residues). Liming carried out considering the chemical characteristics of the soil, the neutralization power of the sources, and the quantity determined by the base saturation method. The data were submitted to analyses of variance, and the means were compared by the Scott-Knott test, with 5% significance. The acidity correction occurred in less time in clayey soil. The coverage on the soil surface influenced the acidity correction, with a dynamic response concerning the analyzed conditions. Shell and dolomitic lime showed adequate efficiency in correcting acidity in both soil textures, with non-standard differences in conditions.

Efficiency of a mine by-product as agricultural liming material and source of zinc

Most Brazilian soils have restrictions on agricultural use related to acidity and nutrient availability. This study aims to evaluate a zinc (Zn) and lead (Pb) mining by-product (Zincal™), regarding its capacity to correct soil acidity, and to serve as a source of Zn. For evaluation of its efficacy, a comparison with dolomite + Zn sulfate was conducted. The experiment was set up in two soils, a Quartzarenic Neosol and a Red Latosol, and conducted under controlled conditions in the laboratory. Treatments consisted in the application of two doses, aiming at 75 and 95% base saturation of both liming materials, as well as in a control treatment without acidity correction. The effect of said treatments on pH, base saturation, Al3+, H+Al, Ca2+, Mg2+, Zn, Mn and Pb contents were evaluated over 120 days. Similar responses were obtained from both liming materials, regarding their capacity to increase the pH of the soil, reduce Al3+ and potential acidity (H+Al), and increase base saturation. Differences observed in these attributes were dose-related. In regard to Ca and Mg, the content released in soil correlates with the content present in the liming materials. Zincal™ released more Mg and less Ca than dolomite, hence proving to be efficient in releasing Zinc.