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 The use of wood residues to produce energy and steam in the pulp and paper industry generates ash waste and sewage sludge that contain nutrients for plants as a potential fertilizer. The objective of this study was to evaluate the possible toxic effects of pelletized waste from the pulp and paper industry using bioindicators. Two controlled experiments were conducted with radish seeds and perennial ryegrass seeds: an experiment to determine the germination index and root growth in soil extracts incubated with pelletized waste, and a pot experiment with ryegrass seeds sown in an amended Alfisol with pelletized wastes in which aerial and root biomass production was determined. The results indicate that the Alfisol amended with pelletized waste did not exhibit any acute or sub-acute toxic effects in radish germination. None of the evaluated pellets showed evidence of deterioration in root elongation, including at a 40 Mg ha-1 dose. The highest root growth was with pellet 2, with ash and sludge at the 40 Mg ha-1 dose, which was higher than that in the control treatment (p<0.05). Seed germination was between 93.9% and 100%. The highest ryegrass aerial biomass occurred with pellets 1 and 2 (p<0.05). Pelletized waste from the paper industry exhibited neither mild nor acute effects of toxicity in both radish seed germination and aerial and root biomass production of ryegrass sown in degraded soil.

Resumen El uso de residuos de madera para producir energía y vapor en industrias de pulpa y papel genera residuos de cenizas y lodos de depuradora que contienen nutrientes para las plantas con potencial fertilizante. El objetivo fue evaluar posibles efectos tóxicos de residuos peletizados de industrias de pulpa y papel mediante bioindicadores. Se realizaron dos experimentos controlados con semillas de rabanitos y ballica perenne; uno determinó el índice de germinación y crecimiento de radículas en extractos de suelo incubados con residuos peletizados. El segundo fue con semillas de ballica perenne sembradas en un Alfisol enmendado con residuos peletizados, determinando producción de biomasa aérea y raíces. Los resultados indican que el Alfisol enmendado con residuos no presenta efectos tóxicos en germinación de rabanitos, incluso con 40 Mg ha-1 no se evidencian deterioros en germinación o elongación de radículas para ningún tipo de pellets. El mayor crecimiento de radícula se obtuvo para pellet 2 con 40 Mg ha-1, siendo mayor al control (p<0.05). La germinación de semillas estuvo entre 93.9% y 100%. La mayor biomasa aérea de ballica se obtuvo con los pellets 1 y 2 (p<0.05). Los residuos peletizados de la industria del papel no presentan efectos de toxicidad leve ni aguda, tanto en la germinación de semilla de rabanito como en la producción de biomasa aérea y de raíces de ballica sembradas en un suelo degradado.

ABSTRACT Pulp and paper mill waste, such as biomass fly ash and sewage sludge, is commonly disposed of in landfills. This waste can be valuable as nutrients and C sources for degraded soils. Ash and sludge samples were chemically characterized before ash/sludge pellets were experimentally manufactured for use as soil amendment. An incubation experiment was carried out with controlled moisture and temperature; nutrient input and N mineralization were evaluated at 0, 15, 30, 45, and 60 d intervals using three pellet types with different proportions of ash, sludge, and gypsum (as a binder) and applied at four doses equivalent to 0, 10, 20, and 40 Mg ha-1. Results indicated that the Alfisol that was amended with pelletized residues increased P Olsen and exchangeable K and Ca contents, as well as soil pH (p < 0.05) in direct response to the applied doses. Organic matter decreased during incubation at all the doses and pellet types (p < 0.05); however, N mineralization did not show a clear pattern during incubation. Nitrogen mineralization potential (N0) was different depending on pellet types and application rates; Pellet 2 (10% sludge) exhibited the highest N0 values, while Pellet 3 (20% sludge) had lower N0 than the control. Pulp and paper mill waste can be used to amend degraded soils by creating sustainable use through pelletizing because it facilitates transport and can evenly distribute sludge and ash on soils in a single application.

Climate change could potentially affect agricultural and forest production in Chile through changes in soil moisture and temperature regimes. In Soil Taxonomy the Soil Moisture Regime (SMR) is used to classify soils at the Suborder, Great Group and Subgroup levels, whereas Soil Temperature Regime (STR) is mainly used at the Family level. Both SMR and STR can be calculated using climatic data input to the Newhall model. Therefore, the objective of this research was to test the hypothesis that long term climate change has already affected the SMR and STR in different locations of the country. Historical values (1912-2015) of monthly precipitation and temperature were input to the model, with the available soil water set to 180 mm, and the offset of air to soil temperature set to 2 °C. The climatic records indicated a general trend of less precipitation in central and south central Chile whereby the SMR changed in Concepción from Ustic-Udic Tropustic to Ustic-Typic Tropustic; in Puerto Montt from Perudic to Udic-Typic Udic; and in Punta Arenas from Aridic-Typic Aridic to Xeric-Typic Xeric. In general, the recent period had more frequent extreme dry years. There was also a general tendency for slightly cooler temperatures mainly along the coast, and warming in Santiago, but the dominant STRs did not change between periods. Additionally, in south central Chile there was a decrease of annual moist days when the soil temperature is > 5 °C, which suggests that in some areas soil temperature and moisture conditions have become somewhat more limiting over time, and, if continued, will likely result in a southerly expansion of the Xeric SMR, and increased need for supplemental irrigation of crops.

The intensive use of agricultural soils reveals the massive application of agrochemicals. There is no follow-up of the presence of pesticide residues in soil or their toxic effects on organisms that are beneficial for agrosystems, such as earthworms (Lumbricus terrestris L.) The objective of this study was to evaluate the effect of pesticides used in horticultural orchards on earthworms, and the use of earthworms as an indicator through carboxylesterase (CbE) activity, which is an enzyme involved in the detoxification metabolism of organophosphorus, carbamates, and pyrethroids. Eight individuals were place in each polyethylene container and the container were buried under the soil surface in two apple orchards, one under organic management and the other under conventional management. The experiment was carried out in triplicate. A control treatment was conducted in the laboratory. The experiment was repeated in autumn, winter, spring, and summer of the 2014-2015 study period. Three internal gut tissues of the earthworm were measured for CbE activity in the laboratory. Results showed higher CbE activity in the crop-gizzard of the control treatment with 14.22 ± 1.00 μmol min-1 mg-1 in winter; the lowest activity was recorded in soil under conventional management in summer with 6.15 ± 2.77 μmol min-1 mg-1 (p ≤ 0.05). There was a seasonal difference in enzymatic activity that was higher in winter and autumn with 14.22 and 13.93 μmol min-1 mg-1, respectively, and lower in summer and spring with 6.15 and 6.31 μmol min-1 mg-1 (p ≤ 0.05), respectively; enzymatic activity was associated with higher pesticide application. It can be concluded that CbE activity is sensitive to the inhibitory action of pesticides and can therefore be used as a biological indicator of agrochemicals.

The need to reduce the use of traditional fertilizers and prevent soil degradation demands the search for new ways of fertilization. The combined application of waste materials (generated by the paper industry) and seaweed may be an alternative source of fertilization. The objective of this study was to evaluate the effect of pellets made of waste materials ash and sludge, produced by the paper industry with the addition of seaweed (Ulva lactuca L.) on the production of lettuce (Lactuca sativa L.) as an indicator plant and N mineralization in the soil. Two trials were conducted on an Entisol soil. The first trial evaluated the productive response of lettuce to the combined application of pellet+seaweed. Lettuce plants were grown in pots under greenhouse conditions for 3-mo. Three types of pellets, with and without seaweed added, were applied in doses of 10, 20, and 30 t ha-1. N mineralization was measured by 12 wk incubation, evaluating the three types of pellets with and without the addition of seaweed. The results showed that all the combined pellet+seaweed treatments had higher aerial biomass production (p ≤ 0.05) and increased chlorophyll content. The aerial biomass production reached 4.16 g pot-1 and was 7-fold higher than pellet treatments without seaweed, while chlorophyll content was 17% higher (p ≤ 0.05). In terms of N mineralization, the maximum release was recorded in the Pellet 3+seaweed treatment, reaching 55 mg kg-1. All the treatments with seaweed (p ≤ 0.05) better higher N mineralization values compared to the treatments without seaweed. Similarly, increased values for potentially mineralizable N and mineralization rate constant were observed in the treatments that included pellets+seaweed and seaweed alone compared to those consisting of pellets alone. The pellets+seaweed amendments resulted in an increase in soil N mineralization and production parameters of lettuce.

The sustainable use of productive resources by agricultural producers in the central valley of Chile should be compatible with economic results so that producers can select an appropriate rotation or succession of annual crops and pasture. The objective of this work was to evaluate the economic behavior of four food crop and supplementary forage rotations using indicators of profitability and profit variability. Productive data were used from a long-term experiment (16 yr) in the central valley of Chile under conditions of irrigation. With productive data and information on historic input/output prices, the real net margin per rotation (RNMR) and its coefficient of variation (CV) were determined. The results indicated that the highest economic benefits and greatest economic stability were obtained with rotations that only included crops, namely sugar beet (Beta vulgaris L. subsp. vulgaris)-wheat (Triticum aestivum L.)-bean (Phaseolus vulgaris L.)-barley (Hordeum vulgare L.) (CR2) and corn (Zea mays L.)-wheat-bean-barley (CR4). These rotations included crops with low CV of the net margin, such as wheat, barley and beans, with values between 0.31 and 0.34. The rotations with crops and pasture, sugar beet-wheat-red clover (Trifolium pratense L.) (2) (CR1) and corn-wheat-red clover (2) (CR3) had lower net margins and more variability of this indicator. Red clover had the highest CV value (1.00). The selection of crops for rotations and their sequence were determining factors in the economic behavior of rotations, affecting the level of RNMR and the degree of inter-annual variability of this indicator. Thus, differences among rotations of 47% in net margin were determined (CR2 vs. CR1), which only differed in the replacement of pasture with red clover (2) by bean-barley. The economic analysis based on the net margin and its variability allow for discriminating among rotations, providing valuable information for producers in deciding which crops to use in rotations.

Long-term crop rotation systems can benefit soil chemical-physical properties and crop productivity. The lack of information on the effect of long-term crop rotations on soil chemical-physical properties for volcanic soils in Chile could restrict reaping real benefits, and make it difficult to take agricultural management decisions, which could lead to possible negative consequences on some soil chemical-physical properties and the environment. The development of information associated with the effect on soil chemical-physical properties with respect to long-term rotation systems and their fertilization management contribute to improving agronomic management decisions for these soils. A study was carried out to assess the effect of six rotation systems replicating fertilization management used by farmers, especially N and P application, and eventually low rates of K, Ca and Mg on soil chemical properties in a volcanic soil after 7 yr in Central South Chile. Affected chemical properties were pH, inorganic N, and available K, along with a general decrease of pH related to fertilization used, which was insufficient in Ca, K, and Mg. Moreover, this soil exhibited high P adsorption capacity (90.2 to 97.5%). Hence, crop rotations that included pasture legumes and crops with high nutrient inputs such as sugar beet (Beta vulgaris L.) generated a less negative effect on soil chemical properties. This study indicates that fertilization management in crop rotation systems must consider the input and output nutrient balances to prevent the negative effect on some soil chemical properties.

Los sistemas de rotación de cultivos de largo plazo pueden tener varios beneficios sobre las propiedades físico-químicas del suelo y productividad de los cultivos. La falta de información sobre el efecto de rotaciones de largo plazo en las propiedades físico-químicas para suelos volcánicos en Chile podría limitar la obtención de beneficios reales, dificultando decisiones de manejo agrícola, con posibles consecuencias negativas en las propiedades físico-químicas del suelo y el ambiente. El desarrollo de información asociada a efectos en las propiedades físico-químicas del suelo en relación al uso de diferentes sistemas de rotaciones de largo plazo y sus manejos de fertilización, podrían contribuir a mejorar las decisiones de manejo agronómico en estos suelos. Se realizó un estudio que evaluó el efecto de seis rotaciones de cultivo que representan el manejo de fertilización utilizado por agricultores, que enfatiza la aplicación de N y P y eventualmente baja dosis de K, Ca y Mg, sobre las propiedades químicas de un suelo volcánico del centro-sur de Chile después de 7 años. Las propiedades químicas afectadas fueron pH, N inorgánico y K disponible, con una disminución general del pH relacionada con la fertilización usada, insuficiente en Ca, K y Mg. A su vez este suelo presentó una alta capacidad de adsorción de P (90,2-97,5%). Consecuentemente, las rotaciones de cultivo que incluyeron leguminosas forrajeras y cultivos con altos ingresos de nutrientes como remolacha generaron un efecto menos negativo en las propiedades químicas del suelo. Para prevenir efectos negativos sobre las propiedades químicas del suelo como lo indicado en este estudio, el manejo de fertilización en sistemas de rotaciones de cultivos debería considerar balances de entrada y salida de nutrientes.

Optimum application rates of poultry litter (PL) spread out on the farmer’s field is a valuable source of available plant nutrients. The aim of this study was to compare the effect of two rates of PL and conventional fertilization (CF) on N mineralization and P, K, Zn, and Cu availability in an Andisol from Southern Chile under controlled conditions. Aerobic incubation was carried out for a 16-wk period. N mineralization rates were higher (61.5%) with the two PL treatments than with conventional fertilizer (23%). CF was associated with high N availability prior to the start of incubation and slight immobilization during the first week, perhaps due to a more rapid conversion of urea into NH4 which was then temporarily immobilized by the microbial biomass. At the start and end of the incubation period, Olsen-extractable P content was generally higher in CF. Due to the high fixation capacity of the soil studied, extractable P values were slightly increased suggesting that PL mineralization is only associated with a low risk of P contamination in volcanic soil. In PL, K, Zn, and Cu availability were higher than in CF. However, values obtained for Cu and Zn were average in relation to referential values used in agricultural soil. The results indicated that PL could be an alternative to conventional fertilizer under the conditions of the present study.

En sistemas agrícolas que utilizan dosis correctas de insumos, la cama de broiler (CB) puede constituir una fuente económica de nutrientes para las plantas. El objetivo de este trabajo fue estudiar el efecto de CB en dos dosis y fertilización convencional (FC) sobre la mineralización de N y la disponibilidad de P, K, Zn y Cu en un suelo volcánico de la zona centro-sur de Chile en condiciones controladas. Una incubación aeróbica fue realizada durante un período de 16 semanas. Las tasas de mineralización de N fueron mayores con los tratamientos de CB utilizados (61,5%) respecto al uso de FC (23%). La FC fue asociada con una alta disponibilidad de N previa al inicio de incubación y leve inmovilización durante la primera semana, debido a una rápida conversión de urea en NH4, el cual fue temporalmente inmovilizado por la biomasa microbiana. Entre inicio y término del período de incubación la concentración de P extractable Olsen fue generalmente mayor con la FC. Debido a la alta capacidad de fijación del suelo, los valores de P extractable fueron levemente incrementados, lo cual sugiere que la mineralización de CB es asociada con un bajo riesgo de contaminación en suelos volcánicos. En la CB la disponibilidad de K, Zn y Cu fue mayor que la FC, sin embargo, los valores para Cu y Zn fueron medios en relación a la referencia usada en suelos agrícolas. Para las condiciones de este estudio, los resultados sugieren que la CB sería una alternativa a los fertilizantes convencionales.

Nitrogen is one of the main inputs of the winter wheat crop (Triticum aestivum L.) in southern Chile. Nitrogen efficient management is basic to optimizing its utilization while decreasing pollution risks and operational costs. Crop response and N use efficiency (NUE, defined as the ratio of yield to mineral N supply, regardless of source) are important for evaluating N requirements of winter wheat, and reaching maximum and economic yields. The objective of this study was to determine the effect of N rate on grain yield, calculate the N rate that maximizes yield, and estimate the optimal grain yield rate and quality of high-yielding winter wheat cv. Kumpa-INIA. Five annual N rates were evaluated in a randomized complete block design during two successive winter wheat cropping seasons on a Vilcún series soil of the Pachic Melanudands family (Andisol) in La Araucania Region, Chile, and subjected to intensive annual crop rotation. Significant effects (P ≤ 0.01) of N rate on grain yield and quality were found. The optimal physical N rate (OPR) in both seasons ranged from 290 to 339 kg ha-1, whereas optimal economic N rate (OER) ranged from 248 to 274 kg ha-1, with yields between 10.2 and 10.1 t ha-1. Nitrogen use efficiency associated to OER was high in both seasons (36.9 and 41.2 kg grain kg-1 N) and fluctuated in similar ranges. Nitrogen rate increased hectoliter weight and grain protein, but decreased NUE.

El N es uno de los principales insumos del cultivo de trigo (Triticum aestivum L.) en Chile. Su manejo eficiente optimiza las dosis, disminuye los riesgos de contaminación y los costos de producción. La respuesta del cultivo y eficiencia de uso de N (NUE, definida como la razón de rendimiento y suministro de N mineral, independientemente de la fuente) son importantes para evaluar los requerimientos de N y alcanzar rendimientos máximos y económicos. El objetivo de este estudio fue determinar el efecto del N en la producción y las dosis que optimizan la productividad y calidad de grano de trigo invernal cv. Kumpa-INIA. Durante 2 años sucesivos en campo, se estudió en un diseño de bloques completos al azar el efecto de cinco dosis de N en un suelo serie Vilcún de la familia de los Pachic Melanudands (Andisol) de la Región de La Araucanía, Chile, bajo rotaciones intensivas de cultivos anuales. El N tuvo un efecto en la productividad y calidad del grano cosechado (P ≤ 0,01). Las dosis óptimas físicas (OPR) de N en ambas temporadas alcanzaron entre 290 y 339 kgha-1, mientras que las dosis óptimas económicas (OER) de N fluctuaron entre 248 y 274 kg ha-1, con rendimientos entre 10,2 y 10,1 t ha-1. Las NUE asociadas a las OER fueron altas en ambas temporadas (36,9 y 41,2 kg grano kg-1 N) y fluctuaron en rangos similares. El incremento de N elevó el peso hectolitro y el contenido de proteína del grano (P ≤ 0,05), mientras que disminuyó la NUE.