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Eucalyptus (Eucalyptus spp.) leads to depletion of nutrients from the soil due to its fast growing nature. Therefore, a pot experiment was conducted to study the effect of zinc (Zn) application on clonal eucalyptus growth, biomass output and its uptake, as well as response of eucalyptus to Zn in soils of three textures. The treatments consisted of eight levels of Zn (0, 5, 10, 15, 20, 25, 30, and 35 mg kg−1 applied through ZnSO4.H2O) in a completely randomized design triplicated in soils of three distinct textures (loamy sand, sandy loam and sandy clay). The plant height, collar diameter, dry weight of shoot and roots, soil plant analysis development (SPAD) readings, Zn concentration and uptake by leaves, stem+branches and roots increased significantly with Zn application. Average dry weight of shoot and roots (31.93 and 15.12 g plant−1, respectively) was significantly highest at 15 mg Zn kg−1 whereas Zn concentration and uptake (18.35 mg kg−1 and 286.2 µg plant−1, respectively) by roots were highest at 20 mg Zn kg−1. The above parameters differed significantly among soils as sandy clay>sandy loam>loamy sand except Zn content and uptake by roots and SPAD values which were highest in sandy loam soil. Loamy sand and sandy loam soil exhibited higher Zn use efficiency, shoot biomass response and uptake response to applied Zn than sandy clay soil. It is concluded to apply 20 mg Zn kg−1 in light soil and 15 mg Zn kg−1 in heavy textured soil for better growth and productivity of eucalyptus. [ABSTRACT FROM AUTHOR]

The agricultural frontier in Brazil advances mainly in areas of sandy soils, where the management of soil fertility is still a challenge, including the practice of liming. Limestone dissolution was investigated under varying doses (0–40 t ha−1) in soil samples with a wide range of textural gradients (5%–74% clay). In view of textural variations and limestone rates, the objective was to generate information regarding pH, the residual liming effect, and exchangeable calcium (Ca) and magnesium (Mg) levels, including under overliming conditions. Throughout the textural gradient, the pH was between 4.2 and 8.5. On more sandy soils (5%–18% clay), overheating (pH > 7) was obtained with ~ 2 t ha−1 of limestone. On clayey soils (37%–74% clay), a similar effect was obtained with ~ 10 t ha−1 of limestone, indicating the marked difference in the acid buffering capacity of these soils. In addition, the equilibrium pH in the context of overliming in sandy soil was higher (8.2) compared with clayey soils (7.8). The residual liming effect was greater in sandy soils due to the lower potential acidity. Regardless of the soil texture, the Ca/Mg ratio increased in the context of overliming. Liming must be carefully applied and requires proper recommendations, especially on sandy soils, avoiding pH ≥ 6.5, a condition that is not suitable for most crops. [ABSTRACT FROM AUTHOR]

The effect of amending "barren" sandy and clay soils with different organic origins on soil organic carbon (SOC) accumulation and permeability is not well known. Therefore, proposing desirable practices to improve their qualities and fertility is a major challenge. To improve soil organic carbon, permeability (PR) and productivity, the two barren soil textures were amended with 0.39 and 0.78 tha−1 (ton per hectare) of manure and lignite, respectively, and irrigated with treated wastewater. During the four years of experimentation, the ranges of increase in SOC of sandy and clay soils were 1.9–3.87 kgm−2, and 0.29–1.40 kgm−2, respectively, and in PR of 35.2–69.3% in sandy soils and 39.3–74.8% in clay soils. These improvements have a major effect on nutrient cycling, significantly improving water and nutrient availability to roots and plants. The levels of improvement increase with the amounts of organic compounds introduced, especially in the clay soil amended with 0.78 tha−1. The proportions of mineralized (lost) SOC were 35.3–62.3% in the sandy soils and 1.0–3.1% in the clay soils. The maximum crop weights produced were approximately 41.2 gm−2 in sandy soils and 1152 gm−2 in clay soils. Thus, amendment of barren sandy and clay soils by all three sources of organic carbon was beneficial, especially for the clay soil. achieved the desired objectives. The gain in clay soils is significantly greater than in sandy soils, which require further study. The type of practice desired by farmers will depend on cost and crop yield. Laboratoire Géoressources. Univerversité de Carthage-Centre des Recherches et Technologies des Eaux, B.P. 273, Soliman 8020 (Tunisia). [ABSTRACT FROM AUTHOR]

Soil hydraulic properties are the key indicators that govern soil functioning. However, sandy and clay soils that cover large areas in semi-arid climate regions have inadequate hydraulic properties for agricultural activities. Therefore, their managements are necessary to help in sustaining agricultural production at acceptable levels. The impact of amendments of these two soil textures with 0.39 t.ha−1 (ton per hectare) and 0.78 t.ha−1 of zeolite and manure and 0.78 t.ha−1 of lignite and irrigated with treated wastewater (TWW) on soil hydraulic properties and roots/crops ratios were investigated. TWW and inputted zeolite, manure and lignite have moderately declined hydraulic conductivities (Kf), and increased bulk densities (BD) and water retention capacities (Wr %) of sandy soils. While in clay soils, an increase of Kf and BD and Wr decreases were observed after addition of manure and lignite. Zeolite addition again decreased Kf. The soil hydraulic property improvements were proportional to the used quantities. The statistical analyses showed that there was a statistically significance for the bulk density indicating a strong interaction between the soil textures and the different amendments. The hydraulic property improvements increased agricultural soil productivities of clay soils. The highest obtained weight crop/root volume ratio was from amended clay soils with manure. The new sandy soil properties remained unfavorable for agricultural activities, except the soil amended with lignite. In the long term, to have a better economic profitability of amended clay soil, the use of 0.78 t.ha−1 of zeolite or lignite is more advisable because they remain longer than manure. [ABSTRACT FROM AUTHOR]

Brazil is an importer of fertilizers and the use of alternative sources is increasing in agriculture. The objective of this study was to evaluate the effect of Dunite rates on magnesium (Mg), silicium (Si), reducing sugars, sucrose and foliar starch, soil chemical attributes and soybean yield [Glycine max (L.) Merril] in two soil types. The treatments consisted in the five Dunite rates (0, 42, 208, 542, and 1542 mg kg−1) in a clayey soil, and five Dunite rates (0, 150, 238, 411, and 933 mg kg−1) in a sandy soil. In both crops and soils, the Mg and Si contents, reducing sugars and foliar glucose, as well as pH, Mg and Si of the soil, and yield components showed a positive response due to the increase of input rates. The Mg nutrition provides lower foliar starch levels, consequently, the best partition of metabolites to plant leads to better development, filling and yield of soybeans. [ABSTRACT FROM AUTHOR]

Soil boron (B) supply is usually used by farmers to correct B deficiency in many crops. The excessive application of this fertilizer may threaten environment components particularly underground water and soil. This study was undertaken to evaluate B migration at different soil characteristics and leaching levels. Three soils were collected from different southwestern Mediterranean areas. Then, three annual leaching rates were tested for each soil: 35 mm, 237 mm, and 565 mm in a sandy soil; 35 mm, 103 mm, and 247 mm in a silty-clay soil; 35 mm, 70 mm, and 140 mm in a clay-calcareous soil. The experiments were conducted in PVC columns filled with 30 cm of the studied soils. 0.5 mg kg−1 of B was applied to the surface of each soil. The results showed that B migration is mainly related to leaching rate and clay content. The soil B losses (y) can be predicted using the regression model: y (mg kg−1) = 0.001a–0.01b+0.14 (adjusted R2 = 0.92) where a = leaching rates (mm) and b = soil clay content (%). The B leaching threat is higher on sandy soil compared to other soils. However, soil B accumulation risk seems to occur particularly in silty-clay and clay-calcareous soils. Further, bioavailable B enrichment was recorded only on silty-clay soil. [ABSTRACT FROM AUTHOR]

Leaching of nutrients, particularly in sandy soil with low nutrient and water holding capacity (WHC), is a major threat to marine and fresh water pollution. Addition of clay soil to sandy soil could be an option to increase water and nutrient holding capacity of sandy soils, but the effect of clay soil addition may depend on the form in which the clay soil is added and the addition rate. Clay soil was added to sandy soil at rate of 10 or 20% (w/w) finely ground (<2 mm) or 2 and 5 mm peds with and without nitrogen (N) and phosphorus (P) fertilizer equivalent to 60 kg N ha−1and 15 kg P ha−1. The clay sand mixture for each treatment was weighed (30 g) in cores with nylon mesh at the bottom. The soils were incubated at 80% WHC for 7 weeks. To obtain leachate, 20 mL reverse osmosis (RO) water was added every week to each core. Leachate was analysed for inorganic N, P, and pH. Soil was analyzed for N, P, and pH before and after the leaching. Clay addition significantly reduced the leaching of N and P compared to sandy soil alone, with greatest reduction by finely ground clay soil and least with 5 mm peds. Compared to sandy soil alone, 83% more N was retained in clay-amended soil and P retention was doubled. This study showed that addition of finely ground clay soil can substantially reduce N and P leaching and thereby increase fertilizer retention compared to sandy soil alone. [ABSTRACT FROM AUTHOR]

Seven grassland experiments on sandy and clay soils were performed during a period of 4 years to estimate the nitrogen (N) fertilizer replacement value (NFRV) of concentrated liquid fractions of separated pig slurry (mineral concentrate: MC). The risk of nitrate leaching when applying MC was compared to when applying mineral fertilizers. Grassland yields in 2009–2012 fertilized with MC were compared with grassland fertilized with two mineral fertilizers: granulated calcium ammonium nitrate and liquid ammonium nitrate (LAN). The mineral fertilizers comprised 50% nitrate-N and 50% ammonium-N, and MC comprised 95–100% ammonium-N. Treatment application rates included zero N and three incremental rates of N fertilization. The liquid fertilizers were shallow injected (0–5 cm). The NFRV of MCs was 75% on sandy and 58% on clay soil with granulated ammonium nitrate as reference, and 89% on sandy and 92% on clay soil with LAN as reference. Risk of nitrate leaching after application of MC, measured in residual soil mineral N post-growing season and N in the upper groundwater in the following spring, was equal to that for mineral fertilizers. [ABSTRACT FROM PUBLISHER]

Salt accumulation has a negative effect on microorganisms, but plant residues may enhance the microbial activity and biomass. An experiment was conducted over 50 days to evaluate the effect of wheat and alfalfa residues on microbial activity and biomass and nitrogen (N) and phosphorus (P) availability in sandy and clayey soils at different salinity levels. Equivalent amounts of calcium (Ca+2) and sodium (Na+) salts were added to both soils. Values of electrical conductivity (EC1:5), denoted S1, S2, and S3 in each soil, were 0.16, 1.10 and 1.98 dS m−1in the sand and 0.19, 0.82 and 1.75 dS m−1in the clay. Residues of wheat and alfalfa were added at 2% (w/w). Cumulative respiration and microbial biomass decreased with increasing salinity, but with residue addition they increased with a greater rate in amended sandy soil than in clay soil, with a more pronounced effect for alfalfa than for wheat residue. After 10 days, with wheat residue available N values were 113, 86, and 71μg in the clay and 144, 114, and 94μg g−1soil in the sand in S1, S2, and S3, respectively. Relative to wheat residue, alfalfa residue increased N availability by 9, 13, and 19% and 22, 24, and 24% in the clay and in the sand in S1, S2, and S3, respectively. Compared to the control, in the clay P availability increased by 33, 57, and 100% with wheat residue and by 58, 128, and 175% with alfalfa residue, whereas in the sand it increased by 92, 45, and 40% with wheat residue and by 130, 145, and 280% with alfalfa residue in S1, S2, and S3, respectively. Availability of N and P increased from day 10 to day 50 in both soils, but with different magnitudes. Residue addition can increase microbial activity and nutrient availability in saline soils, particularly in coarser textured soils. [ABSTRACT FROM AUTHOR]