Soil Management Systems Research Articles

Advances and prospects of biochar in improving soil fertility, biochemical quality, and environmental applications

With the global food deficit increasing and rising climate change issues, there is a need to find green solutions to improve soil fertility and productivity while enhancing soil biochemical quality and reducing the ecological impact of agriculture. Biochar is a potentially cost-effective, carbonaceous resource with many agricultural and environmental applications. As a soil amendment, it improves soil physical and biochemical properties and increases soil fertility and productivity—particularly over the long-term—increasing soil aggregation, water retention, pH, and microbial activities, thus, improving overall soil quality, potentially helping to reduce chemical fertilizer needs over time. The extent of biochar’s impact on soil physiochemical properties varies depending on biochar source, type, size, inherent soil characteristics, cropping system, etc. Moreover, biochar has significant potential in soil and water remediation, especially through its unique adsorption and chemical properties capable to capture and immobilize pollutants such as metal(loid)s, organic pollutants, and hazardous emerging contaminants such as microplastics. Further, biochar has also emerged as a key strategic, cost-effective material to tackle global issues such as climate change mitigation, reducing the net greenhouse gas emission to minimize global warming potential. However, a knowledge gap remains as to understanding the long-term persistence of biochar on agroecosystem, optimal biochar application rate for the diversity of biochar-soil-crop-environmental conditions, interaction of biochar with inherent soil carbon stock, specific mechanisms of biochar’s effect on soil biotic properties, quantification of carbon sequestration, greenhouse gas emissions, synergy or potential antagonistic effects with other carbon sources such as compost, manure, residues, etc., its modification for environmental applications and associated environmental and human risks over long-term. Further research is needed to evaluate the long-term impacts of types and sizes of biochar on overall soil quality to recommend suitable application practices based on soil management and cropping system. Also, its environmental applications need to be finetuned for wider and target specific applications to tackle pressing environmental issues such as soil and water pollution.

Rainfall data adjustment to Volta Redonda macro-region

Most Brazilian cities do not have a proper water and soil management system due to lack of planning in this sector and of an easy-consultation local-hydrological bibliography capable of reinforcing the future creation of a hydrological modeling. Volta Redonda macro-region's case can be added to this statistics, since it accounts for several natural hazards linked to floods and inundations in some specific locations. The aims of the present study are to descriptively analyze monthly rainfall data generated by CEMADEN's rainfall gauges and to assess whether monthly rainfall in the region adapts well to probability Gamma Distribution plots. Rainfall data from four points in Volta Redonda, Barra Mansa and Pinheiral cities, recorded for 48 months, and provided by CEMADEN, were used in the study. Gamma Distribution was adjusted to monthly rainfall data. In conclusion, the probability of having a given monthly rainfall value lower than, or equal to, that recorded for the Pinheiral – Volta Redonda – Barra Mansa conurbation area can be estimated through Gamma Distribution. Values recorded for shape (γ) and scale (β) parameters of Volta Redonda macro-region's municipalities were 1.59 and 79.30, on average, respectively.

Análisis y caracterización de poblaciones bacterianas solubilizadoras de P en un ensayo de larga duración con diferentes secuencias de cultivo

It is well known that different soil use and management systems affect the abundance, activity and composition of the soil microbial community. In this work, the behavior of cultivable bacterial populations and, in particular, P (PSB) solubilizing bacteria in soil samples from a long-term trial with different culture sequences was studied. The results obtained show that the clearing and subsequent agricultural use after 11 years generated a decrease in the population of cultivable bacteria in general, and of P-solubilizing bacteria in particular, with respect to the pristine soil. Isolates with high P solubilization efficiency were obtained from the soils from the different rotations. These efficient isolates were taxonomically classified by 16S RNA analysis as belonging to the genera Bacillus, Paenibacillus, Pseudomonas and Xanthomonas. In particular, the characterization of the culture supernatants of the isolates Pseudomonas koreensis and Paenibacillus pabuli showed they are producers of organic acids. The combined inoculation tests of these two strains on maize plants in a culture chamber revealed a synergistic effect on the growth promotion of this species. The results presented here suggest that although PSB populations are more numerous in pristine soils, certain long-term crop rotations favor the increase of more efficient solubilizing bacteria, an aspect that should be considered when designing future search strategies for potential bioinoculants.

Do different soil use and management systems change root weight?

ABSTRACT The objective to examine the effect of management systems on root dry weight, the percentage distribution of root weight in the soil profile, and the soil carbon content. Treatments consisted of 13 management systems established 22 years ago: degraded pasture; continuous pasture, fertilised, and intercropped with a legume species; continuous pasture with fertilisation; continuous pasture without fertilisation; pasture for four years followed by soybean cropping for four years; pasture for four years followed by soybean cropping for four years, with eucalyptus; soybean cropping for four years followed by pasture for four years; soybean cropping for four years followed by pasture for four years, with eucalyptus; soybean cropping for one year followed by pasture for three years; soybean cropping for one year followed by pasture for three years; continuous summer soybean cropping under conventional cultivation; continuous summer soybean cropping under conservation farming; and continuous no-till summer soybean cropping. Except for degraded pastures, pasture systems have higher root dry mass than soybean cropping systems. The integrated production systems increase the dry weight of the roots, and the carbon content of the soil and reduce aluminum saturation and soil acidity. The highest percentages of roots are found in the 0–0.10 m range.

Can Soil Moisture and Crop Production Be Influenced by Different Cropping Systems?

The different conditions of soil vegetation cover combined with irrigation management and/or agricultural production systems can influence soil moisture content and crop yields. This study investigated the impact of agricultural production systems and center pivot irrigation management on soil moisture content during the cultivation of soybean and off-season corn crops. Two field experiments were conducted during the 2018–2019 growing season in tropical Cerrado soil conditions; one experiment consisted of the application of three irrigation water depths (0%, 50%, and 100% of the crop evapotranspiration) during soybean cultivation in a no-tillage system under ruzigrass (Urochloa ruziziensis) straw, and the second experiment consisted of the intercropped or nonintercropped cultivation of corn hybrids with ruzigrass in an agricultural area with and without the influence of eucalyptus reforestation. The volumetric soil moisture was measured using an electronic soil moisture meter (Hidrofarm), and the 1000-grain mass and yield of the soybean and corn were measured in the two trials. Irrigation and the no-till system did not influence soybean yields. The soybean cultivars NA 5909 RG and TMG 7067 IPRO presented TGM above 180 g, and this represented on average a 22% higher TGM than the BMX DESAFIO RR and CD 2737 RR. The presence of eucalyptus forest promoted a 1.5% increase in soil moisture in the corn crop. Soil management systems, such as irrigation, use cover crops, which may not increase the productivity of soybean and corn crops as expected.

Chemical properties of Oxisol cultivated with corn in management systems of soil irrigated with swine production wastewater.

Waste generated from agribusiness, such as swine production, can be used in agricultural soil; however, certain technical criteria should be followed. The objective of this study was to evaluate the effects of different depths of irrigation with swine wastewater (SW), associated with the soil management system, on soil chemical attributes after two corn crop cycles. The experiments were conducted in the field, in an arrangement with two soil management systems (conventional tillage system - CTS and no-tillage system - NTS) and five depths of irrigation with SW (50%, 75%, 100%, 125% and 150% of evapotranspiration from the crop - ETc). Soil samples were collected at depths of 0-0.1 and 0.1-0.2 m to determine the pH, Ca, Mg, K, Na, Al, P, Fe, Cu and Zn at the end of each crop cycle. Soil nutrient contents increased with the application of SW irrigation in the two crop cycles and in the depths of 0-0.1 and 0.1-0.2 m, mainly with an increase of irrigation depths. No effect of the management systems was observed for the majority of the nutrients evaluated. The content of the heavy metals Cu and Zn remained below the critical limits established by the Brazilian Regulations.

Soil fertility, nutritional status, and sugarcane yield under two systems of soil management, levels of remaining straw and chiseling of ratoons

Soil fertility, nutritional status, and sugarcane yield under two systems of soil management, levels of remaining straw and chiseling of ratoons

Análise dos custos de produção do milho verde sob sistemas de cultivo no Tabuleiro Costeiro Sergipano

Abstract: Although many green corn producers manage their agricultural properties informally, the production of this vegetable is socioeconomically relevant to the Brazilian Northeast. This work aims to estimate and analyze the production costs, profitability and return of green corn in different cultivation systems, in the Coastal Tablelands of Sergipano. For this purpose, data were collected from the 16th to the 18th year of cultivation of a long-term experiment, in a strip experimental design, where each strip corresponds to the soil management system (conventional cultivation (CC), no-tillage (PD)) and minimum cultivation (CM)), and four previous crops (Beans Caupí, Crotalária, Guandu and Milheto) were randomized to corn. Production costs, Gross revenue, Operating profit, Profitability index and Leveling point were determined. Greater productivity and Gross revenue were observed in the PD, and greater disbursements in the CC (R$ 8,184.59). PD had highest operating profit and profitability ratio, where Guandu/PD had the best performance (R$ 8,847.18 and 52.02% respectively). Guandu/CC presented negative operating profit and profitability index, characterizing itself as a non-viable alternative for the farmer. The identification and analysis of production costs is an important tool, as it enables the identification of more profitable crops, being the PD the most recommended.

Soil Acidity and its Distribution in Laterite Soils of Northern Kerala: A Descriptive Analysis

Soil acidity is one of the major constraints of crop production in tropical soils. A study was conducted to examine different forms of soil acidity, contribution of each fraction to total acidity and distribution of exchangeable Al+3, exchangeable H+ detrital laterite rice wetlands of Kerala. Among the series, the Kalikkadavu series reported the highest exchangeable acidity with a mean of 1.66 ± 0.23 meq/100g at a depth of 0-15 cm. Soils from Angadipuram series showed high values for exchangeable hydrogen with a mean of 0.71 ± 0.87 meq/100g and a range of 0.2- 3 meq/100g. Kalikkadavu series reported a high value for exchangeable hydrogen with a mean value of 1.29 ± 0.23 meq/100 g. Regarding potential acidity, Nanminda series reported the highest with a mean value of 40.2 meq/100g. Descriptive statistics of pH dependent acidity data revealed highest acidity for Nanminda series in surface layer with a mean value of 39.27 ± 1.77 meq/100g while in subsurface soils, Arathil series has reported the highest with a mean value of 32.21 ± 3.28 meq/100g. From the paired t-test analysis, significant variations of potential acidity and pH-dependent acidity were observed across surface and subsurface while exchangeable acidity, exchangeable Al+3, exchangeable H+ have shown non-significant variation.Hence, we recommend a proper soil management system that lowers the surface and subsoil acidity in low-pH soil. Again, for best effects in terms of biomass production and economic crop yields, amelioration of soil acidity should be followed by optimum plant nutrient inputs.

The Assessment of Soil Quality in Contrasting Land-Use and Tillage Systems on Farm Fields with Stagnic Luvisol Soil in Estonia

Soil quality indicates the soil’s ability to provide ecosystem services. Reducing the tillage intensity has been suggested as an alternative to conventional tillage for sustaining soil quality. This study aimed to evaluate the effect of soil tillage systems on individual soil quality indicators in comparison to those on grassland with Stagnic Luvisol soil in Estonia. Four soil management systems were compared: no-tillage (NT), minimum tillage (MT), conventional tillage (CT) and grassland (G) as a reference. Soil quality indicators included physical (bulk density, water-stable aggregates, porosity, air-filled pores, moisture content, water-holding capacity, penetration resistance and water permeability), chemical (total N, total soil organic C, permanganate oxidisable C, pH, P, K, Ca and Mg) and biological (earthworm abundance) parameters. CT soils had a significantly lower aggregate stability compared to MT and G soils. The higher penetration resistance of CT under an arable layer suggested the presence of a plough pan. NT improved the soil’s physical quality at 5–10 cm, which was indicated by higher moisture content, water-holding capacity and porosity and a lower bulk density, whereas penetration resistance exceeded 2 MPa in the lower part of the topsoil. NT also had significantly lower total soil organic C and total N compared to MT and G. The absence of tillage in the NT and G systems may have improved the soil’s resistance to moisture loss under dry conditions, which, in turn, improved the soil habitability for earthworms a despite higher density. In general, NT or MT stabilised or increased the soil quality compared to CT.

Seasonal and Soil Use Dependent Variability of Physical and Hydraulic Properties: An Assessment under Minimum Tillage and No-Tillage in a Long-Term Experiment in Southern Italy

Defining the optimal sampling time across the growing season is crucial to standardize sampling protocols for soil physical status monitoring and to achieve comparable results under different experimental conditions and on different sites. In this study, the seasonal variability of soil physical and hydraulic properties under two conservative soil management strategies, minimum tillage and no-tillage, was evaluated in a long-term field experiment. On two sampling dates, autumn 2021 and summer 2022, soil bulk density (BD) and volumetric soil water content at the time of the experiments (θi) were measured in each experimental unit and Beerkan infiltration experiments were performed. The soil water retention curve and the hydraulic conductivity function were then estimated using the Beerkan estimation of soil transfer parameters (BEST) methodology. In this way, the saturated hydraulic conductivity (Ks) and a set of capacitive indicators—plant available water capacity (PAWC), soil macroporosity (PMAC), air capacity (AC) and relative field capacity (RFC)—were obtained. Results underlined the role of soil moisture conditions as a main factor affecting variability in soil physical properties. Different soil moisture under autumn and summer samplings significantly affected BD (1.0093 and 1.1905 g cm−3, respectively, in autumn and summer) and Ks (0.0431 and 0.0492 mm s−1). Relationships observed between BEST-derived variables, such as PMAC (or AC) and RFC, and measured variables, such as BD, showed consistent results, with increases in PMAC to BD decreases. However, a comparison of capacity-based indicators obtained by BEST with those obtained from measured soil water retention curves, in a previous year but under comparable soil conditions, highlighted some discrepancies. This finding drives the focus towards the need to use more robust datasets deriving from experimental measurements or from coupling information obtained from measured and estimated data. Finally, this study provided further evidence that, in the long-term field experiment investigated, the two soil management systems allowed keeping the values of key soil physical quality indicators, such as bulk density and saturated hydraulic conductivity, within the optimal or near- optimal reference ranges.

Fertilization drives distinct biotic and abiotic factors in regulating functional groups of protists in a 5-year fertilization system.

Protists play an important role in nutrient cycling, microbiome stability and soil fertility maintenance. However, the driving force of protistan functional groups remains poorly understood in agricultural ecosystems. We investigated the impacts of fertilization regimes on the diversity, composition and functional groups of protists and further disentangled the effects of multiple factors shaping the community composition of functional groups in a 5-year fertilization regime (CK, no fertilization; M, organic fertilization; MNPK, combined inorganic and organic fertilization; NPK, inorganic fertilization). Fertilization significantly changed the community composition of protists rather than diversity. The MNPK treatment significantly increased the relative abundance of phototrophs and decreased that of the parasites and consumers. Partial least squares path modeling indicated that fertilization indirectly regulated protistan consumers via changes in the P content, which affected the composition of consumers mainly by regulating fungal community composition. Soil moisture (SM) and available phosphorus (AP) were identified as the top predictors for the composition of parasites, and the composition of phototrophs was mainly affected by SM, indicating that parasites and phototrophs were more sensitive to abiotic factors in the fertilization system. Taken together, our findings highlight that fertilization significantly affects the composition of functional groups of protists and their biotic or abiotic regulatory processes, which have implications for the potential changes in their ecosystem functions for soil management systems.

Nutrient Uptake by Soybean Plants in Succession of Cover Crops in Northeast of Brazil

ABSTRACT This study aimed to estimate the nutrient absorption rate in soybean plants cultivated in succession to cover crops and under soil management systems. We performed two experiments with soybean grown on the remaining straw of Crotalaria spectabilis and Pennisetum glaucum (millet), under no-tillage (NT) and minimum tillage (MT), over the cropping years 2016/2017 and 2017/2018, in the Cerrado of Piauí state. The experimental design was a randomized blocks, arranged in split-plots. Plots corresponded to soil management systems and subplots to days after emergence (DAE) of soybean, with 3 replications. Nutrients contents were evaluated at 31, 38, 45, 52, 59, 66, 73, 80, 87, 94, 101, 108 and 115 DAE. Higher soybean dry matter (DM) production occurred in MT compared to no tillage. Crotalaria spectabilis enhanced accumulation of DM and N until stage R2. Accumulation of nutrients and DM in soybean cultivated on the straw of millet and C. spectabilis were similar across soil management systems. The phase of highest accumulation of nutrients and DM in soybean occurs between stages R5 and R7. All the nutrients, except Ca and Mn, are allocated to the grains during physiological maturity, in proportions higher than 50% of the total amount accumulated in soybean plants.

ESTIMATIVAS DE EMISSÃO DE CO2 EM SOLOS CULTIVADOS POR MEIO DE REDES NEURAIS ARTIFICIAS E MODELO LINEAR DE REGRESSÃO

ABSTRACT Quantifying soil gas emissions is costly, since it requires specific methodologies and equipment. The objective of this study was to evaluate modeling by nonlinear regression and artificial neural networks (ANN) to estimate CO2 emissions caused by soil managements. CO2 emissions were evaluated in two different soil management systems: no-tillage and minimum tillage. Readings of CO2 flow were carried out by an automated closed system chamber; soil temperature, water content, density, and total organic carbon were also determined. The regression model and the ANN models were adjusted based on the correlation of the variables measured in the areas where the soil was managed with no-tillage and minimum tillage with data of CO2 emission. Artificial neural networks are more accurate to determine correlations between CO2 emissions and soil temperature, water content, density, and organic carbon content than linear regression.

Como o carbono orgânico opera na distribuição de poros dos solos de textura fina?

ABSTRACT Soil quality is important for providing adequate conduction for the production of food, fiber, and energy without significant alterations in the environment. Fragile soil indexes have been presented as soil quality indicators (i.e., soil porosity and carbon stocks) due to the easy modification by soil management and crop cultivation systems. The objective of this study was to determine and discuss how carbon operates in the distribution of macro- and micropores in fine-textured soils in tropical conditions using sugarcane and coffee production. The experiments were conducted in the region of Triângulo Mineiro, Minas Gerais, Brazil, using sugarcane cultivation (Saccharum officinarum) and coffee (Coffea sp.) in the conditions of the Brazilian Cerrado. It was verified that the distribution of micropores in fine-textured soils was higher than macropores due to the natural increment of clay in the soil. Organic carbon produced organic pores that positively impacted microporosity.

Effect of soil management systems on the rhizosphere bacterial community structure of tobacco: Continuous cropping vs. paddy-upland rotation

Rhizosphere bacteria play important role in soil nutrient cycling and plant growth, and their richness and diversity are influenced by soil management systems. However, the specific changes in tobacco rhizosphere bacterial community structure in continuous and tobacco-rice rotation cropping systems remain uninvestigated. In this study, soil properties and the composition of the rhizosphere bacterial community in tobacco monocropping and tobacco-rice rotation cropping systems were analyzed. Moreover, the comparison of rhizosphere bacterial community structure between tobacco continuous and tobacco-rice rotation cropping systems was performed via high-throughput sequencing. The changes in the composition of the rhizosphere bacterial community were investigated at different tobacco growth stages. The results showed that continuous tobacco cropping increased the soil soluble organic carbon (SOC), total nitrogen (TN), and the content of other nutrients (e.g., available phosphorus and available potassium) compared to tobacco-rice rotation cropping. However, monocropping decreased bacterial alpha-diversity and altered the community composition when compared to the rotation cropping system. At the phylum level, the relative abundance of Proteobacteria, Gemmatimonadetes, and Bacteroidetes increased in the continuous cropping soil, while that of Acidobacteria, Firmicutes, and Actinobacteria decreased. At the genera level, the average abundance of the dominant genus Bacillus varied from 12.96% in continuous cropping libraries to 6.33% in the rotation cropping libraries (p < 0.05). Additionally, several other taxa, such as o_Acidobacteriales and Candidatus_Solibacter decreased from 7.63 to 6.62% (p < 0.05) and 4.52 to 2.91% (p < 0.05), respectively. However, the relative abundance of f_Gemmatimonadaceae and c_Subgroup_6 showed an increase of 1.46% (p < 0.05) and 1.63% (p < 0.05) in the tobacco-rice rotation cropping system, respectively. The results of NMDS indicated that the rhizobacteria community structure differed in the two cropping systems. In tobacco, the rhizosphere bacterial community structure showed no significant changes in the prosperous long-term stage and topping stage, but the composition changed significantly in the mature stage.

Least limiting water range in Oxisol under two conservation tillage systems in sugarcane farming

The Least Limiting Water Range (LLWR) is an indicator of soil physical quality, contributing in information to propose soil management systems in agricultural farming process. This work aimed to assess the usage of LLWR and critical soil bulk density for physical-water quality evaluations, as well as its effect on sugarcane farming under no-tillage and reduced-tillage, in Oxisol. Undisturbed soil samples were collected in 0.00-0.10 and 0.10-0.20 m soil layers, to determine the following attributes: soil bulk density, soil penetration resistance (PR), volumetric water content at field capacity and permanent wilting point and minimum aeration porosity. The LLWR proved to be a good soil physical water quality indicator in sugarcane farming under conservation tillage system. No-tillage presented a greater range of the LLWR when compared to the reduced-tillage, regardless to the PR value adopted as restrictive for sugarcane roots development, increasing the yield of stalks and sugars contents. The critical soil bulk density under no-tillage is between 1.48 and 1.53 Mg m-3 at the RP of 2 and 4 MPa, while under reduced-tillage it is between 1.44 and 1.51 Mg m-3.

Reviews and syntheses: The promise of big diverse soil data, moving current practices towards future potential

Abstract. In the age of big data, soil data are more available and richer than ever, but – outside of a few large soil survey resources – they remain largely unusable for informing soil management and understanding Earth system processes beyond the original study. Data science has promised a fully reusable research pipeline where data from past studies are used to contextualize new findings and reanalyzed for new insight. Yet synthesis projects encounter challenges at all steps of the data reuse pipeline, including unavailable data, labor-intensive transcription of datasets, incomplete metadata, and a lack of communication between collaborators. Here, using insights from a diversity of soil, data, and climate scientists, we summarize current practices in soil data synthesis across all stages of database creation: availability, input, harmonization, curation, and publication. We then suggest new soil-focused semantic tools to improve existing data pipelines, such as ontologies, vocabulary lists, and community practices. Our goal is to provide the soil data community with an overview of current practices in soil data and where we need to go to fully leverage big data to solve soil problems in the next century.

Long-term effect of conservation agriculture on the composition and nutritional value of durum wheat grains grown over 2 years in a Mediterranean environment.

Given the interest in mitigating the consequences of soil deterioration and climate change impacts on durum wheat grain, the objective of our study was to evaluate the effect of two soil management systems - conservation agriculture (CA) and conventional tillage (CT) - on the grain composition and nutritional value of two durum wheat varieties (Karim and Monastir) grown over two cropping seasons (2018-2019 and 2019-2020). The soil management system had an impact on all studied parameters, namely 1000-kernel weight (TKW), proximate composition, energy value, total phenol content (TPC), antioxidant capacities (DPPH and ABTS) and mineral elements (K, P and Na), excluding hectoliter weight. CA resulted in high moisture content, crude protein, P, K, Na, TPC, DPPH and ABTS. However, TKW, crude fat, crude ash, energy value, and total carbohydrate were higher when using CT. A 2-year adoption of conservation agriculture after a long-term conversion enhanced some compositional parameters and nutritional value of durum wheat varieties. The interaction with year and/or variety was very influential. © 2022 Society of Chemical Industry.

Mineralogy and pore size distribution of clayey Oxisols with granular structure and the effect of management systems

There is a general consensus in the tropical literature on the crucial role played by clay mineralogy in the formation of the very stable granular structure of Oxisols, which has been mainly attributed to gibbsite. Gibbsite hinders the face-to-face adjustment of kaolinite plates responsible for the very common block structure. While kaolinite predominates in the clay fraction of most Oxisols, gibbsite occurs in variable contents. Studies have reported that the granular structure is secondarily associated to goethite and hematite, soil organic matter and biological activity. However, the variation of clay mineralogy on the alteration of the pore size distribution of clayey Oxisols with granular structure remains unclear. So, the main aim of this work was to study several granular Oxisols from the Brazilian Cerrado biome, under native vegetation, with clayey texture and variable clay mineralogy, focusing on the influence of the latter on pore size distribution and related physical and hydric attributes, and to assess how these attributes are affected by management practices. Results showed that greater contents of gibbsite led to an increase in the micropores/total pores ratio and a higher frequency of smaller pores distribution. Low mesoporosity and water availability values were common in the studied Oxisols. A case study was conducted to evaluate the influence of management practices in physical and hydric attributes when such soils are incorporated to agricultural production systems. Overall, clayey Oxisols with similar granular structure can have distinguishing physical and hydric environments and soil management systems may constitute important strategies to overcome the intrinsic low water availability of these soils.