ABSTRACT Soil acidity is one of the main factors that reduces productivity in agricultural crops, and it is corrected with materials that neutralize acidification. Among soils affected by acidity are those of volcanic origin. At least 30 % of agricultural soils in Chile are of volcanic origin, and acidity correction practices must be constantly performed. This study aimed to evaluate the effectively of two materials that may neutralize soil acidification and increase yield production in Chilean volcanic soils. An experiment was conducted during the 2019-2020 season, in which different acidity correction materials derived from the cellulose industry [Ash + Dregs (AD) and Ash + Dregs + Sludge (ADS)] were applied in three volcanic soils cultivated with wheat in southern Chile (Chillán, Temuco, and Osorno). Treatments were a control, CaCO3 at an adjusted rate to reach pH 6.0 and AD and ADS at the same rate as CaCO3 and twice the rate. Results indicated that the application of AD and ADS produced similar effects on pH(H2O), Ca2+, Mg2+, and Al3+ contents, cationic exchange capacity (CEC), and Al saturation compared with CaCO3 at the same rate; the effect was directly proportional to the rate used with each AD and ADS. Wheat production at each location was similar for AD, ADS, and CaCO3 at the same rate; however, it fluctuated between 10.1 and 10.4, 5.4 and 6.5, and 10.0 and 10.3 Mg ha-1 at Chillán, Temuco, and Osorno, respectively. Results indicate that these materials are an alternative to be used as a soil acidity correction amendment.

ABSTRACT Organic food production has increased the demand for organic supplies in agriculture. Organic fertilizers are known to have an effect on crop and soil properties, but this effect has been little studied. This research evaluated the effect of seven nitrogen fertilizers allowed for use in organic production and one conventional fertilization treatment adjusted to a similar dose of total nitrogen (N), on chemical properties of two soils of contrasting physicochemical properties (sandy loam Mollisol and silty loam Andisol) incubated under aerobic conditions and controlled 6 times over 112 d. Treatments were: Compost (CO), Fertil (F), Purely Grow (PG), Purely Lysine (PL), Blood meal (BM), Lupine meal (LM), Sodium nitrate (SN), conventional fertilization (CF), and a control without fertilization (CT). The experiment was conducted in a split-plot design for each soil. The results showed that the fertilizers affected soil pH, salinity (electrical conductivity, EC), and the concentrations of phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sulfur (S). In general, the highest values of pH, available P, and exchangeable K, Ca and Mg were obtained using CO in both soils, whereas PL reported the lowest values for most parameters evaluated. The evolution of each parameter over time showed interactions with the fertilization treatment, with a steady decrease in pH and an increase in EC in both soils. Differences in the average values of chemical properties during incubation with respect to their initial values were related to the physicochemical and organic characteristics of each soil.

The Bradford-reactive soil protein (BRSP) fraction includes glomalin, a glycoprotein produced by arbuscular mycorrhizal (AM) fungi able to bind some metals, such as copper (Cu), which could promote the bioremediation of Cu-polluted soils. This study aimed to analyze the Cu-binding capacity of BRSP in Oenothera picensis that was inoculated or not inoculated with AM fungi. O. picensis plants were established in a Cu contaminated sterilized soil and treated with the following: i) uninoculated (-M); ii) inoculated with native AM fungal propagules (+M); or iii) inoculated with a Claroideoglomus claroideum (CC) strain isolated from non-contaminated soil. In each case, five Cu levels were applied to the soil (basal level 497.3 mg Cu kg-1): 0 (T1); 75 (T2); 150 (T3); 225 (T4); and 300 mg Cu kg-1 (T5). A high BRSP accumulation in AM inoculated treatments, especially with CC, was observed. A higher Cu-bound-to-BRSP content was found with increasing Cu concentrations, representing up to 20-22% of the total Cu in the soil. Moreover, a higher root Cu concentration in +M was observed. These results suggest a high Cu binding capacity by BRSP, which is a relevant aspect to consider in the design of bioremediation programs together with the selection of endemic metallophytes and AM fungal strains, which are able to produce glomalin at high quantities.