Combined effects of hydrothermally-altered feldspar and water regime on cadmium minimization in rice.

The accumulation of cadmium (Cd) in grains and edible parts of crops poses a risk to human health. Because rice is the staple food of more than half of the world population, reducing Cd uptake by rice is critical for food safety. HydroPotash (HYP), an innovative potassium fertilizer produced with a hydrothermal process, has the characteristics of immobilizing heavy metals and potential use for remediating Cd-contaminated soils. The objective of this study was to evaluate the HYP as a soil amendment to immobilize Cd in acidic soils and to reduce the accumulation of Cd in rice tissues. The experiment was performed in a greenhouse with a Cecil sandy loam soil (pH 5.3 and spiked with 3 mg Cd kg-1) under either flooding conditions (water level at 4 cm above the soil surface) or at field capacity. Two hydrothermal materials (HYP-1 and HYP-2) were compared with K-feldspar + Ca(OH)2 (the raw material used for producing HYP), Ca(OH)2, zeolite, and a control (without amendment). After 30 days of soil incubation, HydroPotashs, the raw material, and Ca(OH)2 increased both soil solution pH and electrical conductivity. These materials also decreased soluble Cd concentration (up to 99.7%) compared with the control (p < 0.05). After 145 days, regardless of the materials applied, plant growth was favored (up to 35.8%) under the flooded regime. HydroPotash-1 was more effective for increasing dry biomass compared with other amendments under both water regimes. HydroPotashs reduced extractable Cd in soil, Cd content in plant biomass at tillering and maturing stage, and were efficient in minimizing Cd accumulation in rice grains.

Effects of the amendment with almond shell, bio-waste and almond shell-based biochar on the quality of saline-alkali soils.

This study aimed to evaluate the effect of the amendment with almond shell bio-waste (AS) and almond shell-based biochar (ASB), in different mass ratios (5, 10, and 15%), on the physicochemical properties of three different saline soils, using the growth of arugula seedlings as a bioindicator of the enhancement achieved. Data were analyzed based on a completely randomized design in a factorial arrangement with four replications. The results showed that the low-salinity soil (T1) presented the best physicochemical characteristics and growth parameters. The addition of AS and ASB in low proportions to the saline soils reduced the pH and electrical conductivity values. An increase in the amendment proportion led to an increase in these variables. Moisture, organic matter, and organic carbon increased, and the cation exchange capacity decreased, generating positive effects on soil quality. The values of exchangeable sodium percentage (ESP) showed that T3 presented the highest sodicity, followed by T2 and T1. The treatment with 5% ASB produced better results regarding total plant length, fresh and dry weights, leaf area, and leaf chlorophyll content. Finally, linear regression models were applied to describe the dependence of the agronomic variables on the ratio of biochar added.

Insect frass and exuviae to promote plant growth and health.

Beneficial soil microorganisms can contribute to biocontrol of plant pests and diseases, induce systemic resistance (ISR) against attackers, and enhance crop yield. Using organic soil amendments has been suggested to stimulate the abundance and/or activity of beneficial indigenous microbes in the soil. Residual streams from insect farming (frass and exuviae) contain chitin and other compounds that may stimulate beneficial soil microbes that have ISR and biocontrol activity. Additionally, changes in plant phenotype that are induced by beneficial microorganisms may directly influence plant-pollinator interactions, thus affecting plant reproduction. We explore the potential of insect residual streams derived from the production of insects as food and feed to promote plant growth and health, as well as their potential benefits for sustainable agriculture.

Biochar impacts on soil chemical properties, greenhouse gas emissions and forage productivity: A field experiment.

Biochar is a promising alternative to agricultural productivity and climate change mitigation. However, quantitative data are needed to better understand the productivity and greenhouse gas (GHG) emissions from agricultural fields amended with biochar. To assess the impacts of the four biochars on soil properties, forage productivity, and GHG emissions, a 1-year field experiment was conducted in a Humic Haploxerands (Andisol). Three manure-derived biochars and one wood residue biochar (all pyrolyzed at 550 °C) were applied at rates of 1% (equivalent to 11 t ha-1) in two parallel and independent experiments. The changes in (i) soil chemical properties and yield of Sorghum sudangrass (S. bicolor×S. bicolor var. Sudanese) and (ii) soil CO2 and N2O emissions were monitored. Two controls, with and without NPK, were included. The added amendments produced from residues of poultry and pig systems increased soil pH by 0.73 and 0.19 units, respectively. Increased sorghum yield were associated with fertilizer and the liming potential of the added biochar. Soil total carbon (TC) increased with the addition of different biochars, especially during the wood biochar treatment. Biochar application, regardless of the feedstock, had no significant impact on the cumulative soil CO2 emitted after a year. Soil N2O fluxes decreased (23%-50%) in treatments containing biochars with low mineral N contents and high C stability (i.e., low H:OC and Cox:TC ratios). NPK treatment resulted in the highest N2O emissions. Wood residue-derived biochar has a great potential in mitigating climate change, reducing soil N2O emissions, and promoting soil C storage. Manure-derived biochars could be instrumental in circular economy livestock systems, where pyrolyzed animal manure can satisfy the demand for nutrients and/or liming of Andisols under sustainable forage models.

Hydrogel composed of potassium acrylate, acrylamide, and mineral as soil conditioner under saline conditions

Hydrogels have potential as soil conditioners due to their high capacity to retain water and mitigate soil salinity. However, investigations under saline conditions are necessary because there are losses in both water absorption and salinity mitigation depending on the composition of hydrogel and ions involved in salinity. In this work, we studied a commercial hydrogel in two experiments. The first experiment was conducted in the laboratory to evaluate the absorption by the hydrogel of water with electrical conductivity (EC) of 0.5, 1.5, 3.0, and 4.5 dS m-1, promoted by NaCl. The second experiment was conducted in a greenhouse in a 2 × 4 factorial scheme (with and without hydrogel × EC of the first experiment). Although salinity reduced water absorption by hydrogel by 84 %, the polymer applied in a sandy soil under saline conditions reduced water losses by 58 %. However, hydrogel did not increase the final soil moisture (~ 0.10 g g-1). The polymer reduced Na+ concentration in leachate from 1,499 to 1,219 mg L-1 at the highest salinity level (4.5 dS m-1), but it increased Na+ soil availability by 0.1 mg kg-1 in comparison with polymer absence. Hydrogel application increased Na+ content in plants from 9 to 13 mg kg-1 at the highest salinity, while K+ content was 10 to 16 mg kg-1 lower than that observed without a polymer. Hydrogel 0.07 % (w/w) reduced maize biomass, indicating damage by monovalent ions, compromising the polymer potential under salinity.

Identification of organic contaminants in vinasse and in soil and groundwater from fertigated sugarcane crop areas using target and suspect screening strategies.

This work evaluated for the first time the sustainability of vinasse reuse as a fertilizer in sugarcane crops by assessing the occurrence of organic contaminants and their potential for dissemination to soils and groundwater in fertigated areas. A comprehensive screening of organic contaminants was performed in vinasse, soil and groundwater using target analysis, to investigate the occurrence of multiple-class antibiotics, in combination with suspect screening using NORMAN Digital Sample Freezing Platform. Even though antibiotics are used in the ethanol production process and were expected to be ubiquitous contaminants, they were not detected in any of the samples. Nevertheless, the HRMS-based wide-scope suspect screening (including >7800 substances such as pharmaceuticals, agrochemicals, preservatives and industrial chemicals) allowed the tentative identification of 56 compounds, mostly pesticides, food additives, industrial and naturally occurring substances. Results showed no overlap between the compounds detected in vinasse and environmental samples, suggesting that the pollutants found in soil and groundwater might come from alternative sources other than vinasse reuse.

Agricultural use of Samarco's spilled mud assessed by rice cultivation: A promising residue use?

Mining activity is one of the main responsible for accumulation of potentially toxic elements in the environment. These contaminants are absorbed by plants served as food that could be a risk to human health, such rice. Rice is a staple food with known accumulation of toxic elements. The recent collapse of a mining dam operated by Samarco Mining Company spilled around 50 million m3 of Fe-mining waste in the environment, including rivers and farming areas. In the present study, concentrations of As, Cd, Hg, Pb, Co, Zn, Mn, Cu, Fe, Al, Se, and Sr were determined in soils, roots and grains of rice plants cultivated in soil containing Samarco's residual mud (0, 16, 34 and 50%). Further, rice plant agronomic parameters (chlorophyll, carotenoids, grain yield, mass, height) were assessed. Rice cultivated at Samarco's residual mud produced grains with low levels of As, Cd and Pb. However, the excess of mud (50%) during the rice cultivation reduced roots' growth and grains yield. Chlorophyll (a and b) and carotenoids contents were significantly lower in all mud cultivations, mainly mud-50%. Our findings suggest that plant alterations induced by the mud were associated to the deficiency of nutrients and the physical properties of the mud. Soil fertilization by organic matter and top soil provided conditions for plant development. Therefore, considering the experimental conditions here used, we showed that is possible the use of the affected land for agriculture and reforestation after soil amendment.

Effect of organic amendment on stem canker and black scurf disease of potato (Solanum tuberosum) / Efeito da alteração orgânica sobre o cancro da haste e doença dos tuberculos pretos da batata (Solanum tuberosum)

An experiment was conducted at Tuber Crops Research Centre, BARI, Bogra during 2008-2009 to evaluate the organic amendment for controlling the stem canker and black scurf of potato. The different kinds of organic amendments were: T1 =Poultry refuse (PR) at 4 t ha-1, T2 =PR at 5 t ha-1, T3 =PR at 6 t ha-1, T4 =Mustard oil cake (MOC) at 300kg ha-1, T5 =MOC at 500kg ha-1, T6 =Neem oil cake (NOC) at 300kg ha-1, T7 =NOC at 500kg ha-1, T8 =Sawdust burning and T9 = Control. The experiment was laid out in a randomized complete block design (RCBD) with four replications. The organic amendment significantly influenced the disease incidence, yield attributes and yield of potato. The lowest disease incidence (17.5%) and per cent disease index (9.99) were found in T3 (poultry waste at 6 t ha-1). The minimum russet, deformed and Sclerotia infected tubers were also recorded in poultry waste at 6 t ha-1. The highest healthy tubers and tuber yield were found in the same treatment. Therefore, poultry manure 6 t ha-1 along with recommended dose of chemical fertilizer can be recommended to produce healthy tubers and maximum tuber yield of potato.

O experimento foi conduzido no (Centro de Pesquisa em Tubérculos ) Tuber Crops Research Centre, Bari, Bogra durante 2008-2009 para avaliar a alteração orgânica e controlar o cancro da haste e Black Scurf da batata. Os diferentes tipos de alterações orgânicas foram: T1 = Poultry recusar (PR) a 4 t ha-1, T2 = PR a 5 t ha-1, T3 = PR em 6 t ha-1, T4 = bolo de óleo de mostarda (MOC) em 300 kg ha-1, T5 = MOC em 500 kg ha-1, T6 = bolo de óleo de Neem (NOC) em 300 kg ha-1, T7 = NOC em 500 kg ha-1, T8 = queima de serragem e T9 = Controle. O delineamento experimental foi em blocos casualizados (RCBD) com quatro repetições. A alteração orgânica influenciou significativamente a incidência da doença, os atributos de rendimento e produtividade da batata. A menor incidência da doença (17,5%) por cento do índice de doença (9,99) foram encontrados em T3 (resíduos de aves a 6 t ha-1). O russet mínimo, deformado e Sclerotia tubérculos infectados também foram registrados em resíduos de aves a 6 t ha-1. O rendimento mais elevado tubérculos saudáveis e tubérculos foram encontrados no mesmo tratamento. Portanto, aviário 6 t ha-1, juntamente com a dose recomendada de fertilizante químico pode ser recomendado para a produção de tubérculos saudáveis e rendimento máximo dos tubérculos de batata.