Reduce Soil Degradation Research Articles

Improving the Forecast of the Effectiveness of Reclamation Measures to Reduce Food Security Risks

The analysis of the current state and prospects for implementation of the integrated land reclamation program in Krasnodar Territory is one of the main tasks in the development of the agro-industrial complex to reduce the risks of industrial safety in the region. The article pays special attention to the crucial importance of the agro-industrial complex of the region in supporting and ensuring food security of the country on the example of Krasnodar Territory, since the Southern region makes a great contribution to the formation and development of the agro-industrial complex of the country. In accordance with the documents of the Program, Krasnodar Territory is a key element in the creation of the “main food base of the country” on the territory of the Southern Federal District on the basis of the formation of a national mega cluster of the agro-industrial complex. The article also pays special attention to the problematic aspects and difficulties in the practice of creating and operating a reclamation complex in the regions of Southern Russia. Taking into account the accumulated experience, the key components of the integrated land reclamation of Krasnodar Territory are identified, providing for improvement of physical and physical-chemical properties of soils through the use of modern irrigation technologies, introduction of new methods for removing excess water during the growing season and expansion of the use of progressive methods of anti-erosion land reclamation. Forecasting the effectiveness of the use of complex land reclamation in the conditions of Krasnodar Territory should show its feasibility and necessity. Thanks to the implementation of comprehensive measures, it is possible to reduce soil degradation, increase the effectiveness of drainage systems, as well as irrigation in general, and ultimately get a positive economic effect. An example of such an economic approach to agricultural lands of Kuban can be the improvement of the overall organic and chemical state of soils, which is mainly reflected in an increase in the gross harvest of agricultural crops.

Beneficial services of Glomalin and Arbuscular Mycorrhizal fungi in degraded soils in Brazil

Reducing soil degradation and its impacts on the environment have been one of the main challenges of the 21st century, exacerbated by a direct link between increases in the human population and soil degradation that raises current and future food security concerns. Despite this, experiences worldwide reveal that degraded land restoration projects have either achieved little success or failed. Thus, understanding the underlying causes and devising appropriate restoration mechanisms is crucial. Soil amelioration using beneficial microorganisms, particularly arbuscular mycorrhizal fungi (AMF), is essential and pragmatic. Glomalin, a type of glycoprotein produced by arbuscular mycorrhizal fungi in the phylum Glomeromycota, contributes to the mitigation of soil degradation. Moreover, AMF and glomalin are highly correlated with other soil physico-chemical parameters and are sensitive to changes in the environment. As a result of this, they have been recommended for monitoring the recovery of degraded soil or stages of soil degradation. In this review, we discuss the role of AMF and glomalin in the restoration of degraded soils, including improvements to the soil structure and soil organic matter (SOM), microbial activity, reduction of fertility loss, bioremediation, and mitigation of the effects of drought and saline stress. We highlight the research gaps and discuss the prospects. This knowledge will improve our understanding of the ecological conduct of glomalin and AMF, stimulate future research, and be useful to sustainable restoration of degraded lands. Furthermore, we discussed the challenges and obstacles in the legislation and future perspectives on the production of inoculants based on AMF in Brazil.

IMPACTO DEL CAMBIO EN EL MANEJO DEL CULTIVO DE TRIGO DE CONVENCIONAL A ORGÁNICO SOBRE LAS COMUNIDADES FÚNGICAS CULTIVABLES DEL SUELO EN EL VALLE DEL YAQUI, MÉXICO

El uso de fertilizantes orgánicos en el Valle del Yaqui tiende a reducir la degradación del suelo en la producción de trigo, sin embargo, todavía no se han evaluado los impactos biológicos de esta práctica en el suelo. El objetivo de este experimento fue cuantificar el impacto del cambio en el manejo del cultivo de trigo, de convencional a orgánico, sobre la reducción de la degradación fúngica del suelo, por medio del análisis de sus poblaciones fúngicas cultivables y su diversidad. La hipótesis fue que la aportación de fertilizantes orgánicos al cultivo de trigo produce cambios positivos en las propiedades fisicoquímicas del suelo, lo cual beneficia a las poblaciones de hongos, y disminuye su degradación. Tres campos comerciales de trigo se seleccionaron con 1) fertilización sintética convencional (SF), 2) fertilización sintética más fertilización orgánica (SF+OF) y 3) sólo fertilización orgánica (OF). Los sitios de estudio bajo OF y SF+OF vs. SF mostraron mayores, contenidos de materia orgánica (1.5, 1.6 vs. 0.45%), población de hongos (1.7x105, 9.1x104 vs. 1.6x104 CFU g-1 de suelo seco) y diversidad (12, 12 vs. 2). Con base en el análisis filogenético, se aislaron 9, 11 y 2 géneros de hongos de los sitios de estudio bajo fertilización orgánica, sintética + orgánica y sintética, respectivamente. La diversidad metabólica de las cepas fúngicas obtenidas mostró que la producción de indoles osciló entre 0.5 y 65.4 μg mL-1; el hongo Stachybotrys sp. TSM35 fue el productor de indoles mayor. La solubilización de fosfatos mayor (21%) se observó en la cepa Talaromyces pinophilus TSO42 y la cepa con producción de sideróforos mayor (33.9%) fue Volutella ciliata TSM43. Además, el 60% de las cepas mostraron riesgos potenciales para la salud (α- o β-hemólisis). La rotación de convencional a orgánico en el cultivo del trigo logró cambios positivos en las propiedades fisicoquímicas del suelo, en la diversidad y características metabólicas de las poblaciones fúngicas cultivable. El control de la calidad microbiológica de los fertilizantes orgánicos se necesita para evitar riesgos microbiológicos en los sistemas agronómicos, causados por la introducción de cepas con potencial patogénico.

Conservation agriculture for food security and climate resilience in Nepal

AbstractAchieving the sustainable development goals of the United Nations requires innovations in agriculture and development of climate‐smart and economically feasible approaches for smallholder farmers in developing countries. Historical climate data of Nepal, which include 116 yr since 1901, has shown an increasing trend for average temperature by 0.016 °C yr–1 whereas precipitation has shown a decreasing trend by 0.137 mm yr–1. Such weather trends could enhance glacier melt associated flooding, and delayed monsoon rainfalls negatively impacting the agricultural production. The Nepalese government is promoting conservation agriculture (CA) through development of low‐cost technologies that can be used effectively in difficult terrains. Such techniques include crop diversification, crop rotation, cover crops, and minimum tillage; all of which can reduce soil degradation. In addition, increasing crop residue retention can result in greater C sequestration and crop yield and reductions in greenhouse gas emissions. However, there is still lack of consensus on the merits of CA in the context of smallholder farming systems in Nepal. This paper reviews existing literature and provides an overview of farming practices in Nepal, highlights near‐term challenges associated with climate change and food security, and discusses the role of CA as a climate‐smart strategy to minimize soil degradation and improve food security.

Brief Review of Minimum or No-Till Seeders in China

Minimum or no-till seeding technology is the core of conservation tillage, which can effectively reduce soil degradation by water and wind erosion. It is an essential part of agricultural modernization. The anti-blocking technology is the key to realize minimum or no-till seeding technology. According to the principle, it can be divided into three types: straw-flowing type, gravity-cutting stubble type, and power-driven type. Emphasis is placed on the anti-blocking principle, technical characteristics, and development trends of minimum or no till seeders based on three different anti-blocking principles. In view of analyzing and summarizing the advantages and disadvantages of three technologies and typical machines, the future development trends of minimum or no-till seeders were prospected as follows: (1) strengthening research on basic theories and integration mechanisms; (2) building a big data-sharing platform for seeding operations; (3) establishing and improving specific systems of minimum and no-till seeders with China character.

The effects of land management patterns on soil carbon sequestration and C:N:P stoichiometry in sloping croplands in southern China

Excessive use of sloping soil in agriculture can result in loss of soil carbon (C) and stoichiometric imbalances, leading to soil degradation and a reduction in ecosystem services. Therefore, studying the effects of different utilization patterns on soil C stocks and stoichiometry is critical for the sustainable development of agriculture on uneven terrain. Here, we conducted a 7-year field study of cropland with a 10% slope, comparing soil C, nitrogen (N), and phosphorus (P) stocks and ratios between experimental plots of naturally abandoned land and different planting patterns (peanuts, daylily, oil tea planting with bare floor or inter-row coverage of straw, white clover or peanuts). We found that oil tea planting without inter-row coverage significantly lessened soil total C, microbial C and N, soil organic C, dissolved organic C, readily oxidizable C and available N compared with natural abandonment, whereas peanuts showed smaller differences, and daylily planting was most similar to natural abandonment. We also found that most planting patterns exacerbated soil C and P imbalance through the combination of C loss and P addition from fertilization. Our results show that inter-row coverage of straw or white clover can significantly alleviate these adverse influences. The atomic C:N and C:P ratios across all experimental plots were 5.10 ~ 30.5- and 0.675 ~ 8.13-fold lower, respectively, than the median values for Chinese soils, indicating that soil restoration or reasonable utilization has a high C sequestration potential, but it may be limited by P. These results suggest that perennial crops, such as oil tea with intercropping, can be nearly as effective as natural forest succession to reduce soil degradation on sloped farmland.

COLMENA: A Culture Collection of Native Microorganisms for Harnessing the Agro-Biotechnological Potential in Soils and Contributing to Food Security

COLMENA is a microbial culture collection dedicated to the characterization, classification, preservation, and transferal of native microorganisms isolated from various agro-systems and other ecosystems in Mexico. This collection aims to protect microbial diversity, reducing soil degradation, but also exploiting its agro-biotechnological potential. So far, COLMENA has isolated and cryopreserved soil microorganisms from different crops in two major agricultural regions in Mexico, the Yaqui Valley, Sonora, and the Fuerte Valley, Sinaloa. COLMENA has specialized in the identification and characterization of microbial strains with metabolic capacities related to the promotion of plant growth and the biocontrol of phytopathogens. Thus, COLMENA has identified several promising plant growth-promoting microbial (PGPM) strains due to their metabolic and genetic potentials and their beneficial effects in vivo and field trials. These findings demonstrate the biotechnological potential of these strains for their future use in profitable agricultural alternatives focused on enhancing global food security. To share the knowledge and results of the COLMENA team’s scientific research, a virtual platform was created, where the database of the studied and preserved microorganisms is available to professionals, researchers, agricultural workers, and anyone who is interested.

Effects of conservation agriculture on physicochemical soil health in 20 maize‐based trials in different agro‐ecological regions across Mexico

AbstractMaize (Zea mays L.) is Mexico's primary staple food, but the Country's degrading soils and climate variability limit its productivity. Conservation agriculture (CA), a management technique that combines minimal tillage, permanent soil cover, and crop diversification, could reduce soil degradation and help improve soil health. There is however a lack of information about the effects of CA on soil health in the diverse agroecological conditions in Mexico. This study reports results of a field trial network established to adapt CA to Mexico's diverse cropping systems and local conditions. Physicochemical soil health, also referred to as soil quality, was studied in 20 trials in agro‐ecologies ranging from handplanted traditional systems to intensive irrigated systems, initiated between 1991 and 2016. Soil in CA was compared to the local conventional practice (CP), which commonly involves tillage, residue removal, and continuous maize production. Across the sites, organic matter and nitrates were higher in the top (0–5 cm) layer of soil and soil aggregate stability was greater under CA than under CPs. For other soil health parameters, such as nutrient content, pH or penetration resistance, the effects of management varied widely across sites and soil types and most were determined more by local soil type than by management. CA increased maize yields at most sites and on average by 0.85 ± 1.80 t ha−1. Given the significant variation across agro‐ecologies, local adaptive trials are important to assess the effects of CA on soil health and fit the practice to local conditions.

Impact of Ambient and Elevated [CO2] in Low Light Levels on Growth, Physiology and Nutrient Uptake of Tropical Perennial Legume Cover Crops.

At early stages of establishment of tropical plantation crops, inclusion of legume cover crops could reduce soil degradation due to erosion and nutrient leaching. As understory plants these cover crops receive limited irradiance and can be subjected to elevated CO2 at ground level. A glasshouse experiment was undertaken to assess the effects of ambient (450 µmol mol−1) and elevated (700 µmol mol−1) levels of [CO2] on growth, physiological changes and nutrient uptake of six perennial legume cover crops (Perennial Peanut, Ea-Ea, Mucuna, Pigeon pea, Lab lab, Cowpea) under low levels of photosynthetic photon flux density (PPFD; 100, 200, and 400 µmol m−2 s−1). Overall, total and root dry biomass, total root length, specific leaf area, and relative growth rates were significantly influenced by levels of [CO2] and PPFD and cover crop species. With few exceptions, all the cover crops showed significant effects of [CO2], PPFD, and species on net photosynthesis (PN) and its components, such as stomatal conductance (gs) internal CO2 conc. (Ci), and transpiration (E). Increasing [CO2], from 450 to 700 μmol mol−1 and increasing PPFD from 100 to 400 μmol ּm−2 ּs−1 increased PN. Overall, the levels of [CO2], PPFD and species significantly affected total water use efficiency (WUETOTAL), instantaneous water use efficiency (WUEINST) and intrinsic water use efficiency (WUEINTR). With some exceptions, increasing levels of [CO2] and PPFD increased all the WUE parameters. Interspecific differences were observed with respect to macro-micro nutrient uptake and use efficiency. With a few exceptions, increasing levels of [CO2] from 450 to 700 μmol mol−1 and PPFD from 100 to 400 μmol m−2 s−1 increased nutrient use efficiency (NUE) of all nutrients by cover crop species.

Climate Adaptation and Conservation Agriculture among Peruvian Farmers

Peruvian agriculture will likely experience serious economic impacts of climate change, with changing rainfall and temperature patterns forcing farmers to confront abnormal climate conditions. In this context we study the impact of climate shocks on the agricultural practices of farmers who grow two main staples: maize and potato. We focus on four types of agricultural techniques: (a) those that reduce soil degradation, (b) those that conserve water, (c) the application of inorganic fertilizer, and (d) the application of pesticides and herbicides. We combine three rounds of cross‐sectional data from the Peru National Agricultural Survey with long‐term climate data to construct georeferenced shocks of abnormal rainfall levels and variation. Our empirical strategy controls for time‐invariant characteristics of small localities, secular time trends, and farmer and farm characteristics to estimate how shocks affect farmers' choices in subsequent growing cycles. Our findings show that: (a) farmers reduce soil conservation practices after one year of high rainfall, but multiple years of low rainfall increase adoption significantly; (b) the rate of pesticide use increases by eight percentage points following a drought year but is insensitive to multiple shock years; (c) water conservation measures are used less after high precipitation or when volatility was unusually low, and multiple years of insufficient rain tend to enhance this response; and (d) fertilizer use is less sensitive than other outcomes to weather fluctuations. These findings suggest that understanding how responsive farmers' practices are to weather shocks can inform policy design and help mitigate risks from changing weather patterns.

ИМПОРТОЗАМЕЩЕНИЕ КАК ОСНОВА УСТОЙЧИВОСТИ ПОДОВОЛЬСТВЕННОЙ СИСТЕМЫ РОССИИ

The article is devoted to assessing the impact of the implementation of the import substitution policy on food security and the stability of the food system in Russia in the face of new challenges and risks. Globalization processes have increased the impact of uncertainties, including the coronavirus pandemic, on the sustainable functioning of national food systems. The analysis of changes in the macroeconomic parameters of the country’s food security is carried out. A study of self-sufficiency indicators, coefficients of import priority and import load showed a decrease in the dependence of the domestic market on imports for the main types of products. The problematic segments of the food market were identified: milk and dairy products, fruits and berries. Even with high production rates in recent years, the market remains highly dependent on external supplies of fruits and berries, milk and dairy products. Import substitution processes have only slightly affected the non-agricultural stages of the agri-food complex. The pro- duction potential of the food system of Russia re- mains highly dependent on imports of the main types of machinery and equipment, technologies and innovative developments, which is an external risk of its sustainability. The strategic priorities for the development of the agri-food complex, which ensure the sustainability of the country’s food system, have been substantiated. It is concluded that the current trend in the development of food systems is not just an increase in the production of agricultural products and food. When developing and implementing agricultural policy, it is necessary to take into account the multi- functionality of food systems, which suggests a balance between meeting the growing demand for food and rational use of resources, using innovative production methods and increasing food quality, reducing environmental pollution, reducing soil degradation and greenhouse gas emissions, etc.

Soil morphostructural characterization and coffee root distribution under agroforestry system with Hevea Brasiliensis

Land use and tillage practices may change soil structure and undermine sustainable agriculture; however, such changes are hardly identified in the short term. In this sense, agroforestry systems have been used to reduce soil degradation and promote sustainable production in coffee plantations. These areas are expected to have well-structured soils and hence improved root distribution. This study aimed to evaluate soil quality by the morphostructural and root distribution analyses comparing open-grown coffee and coffee in agroforestry systems with rubber trees for 19 years, in an Oxisol in northern Paraná State (Brazil). Treatments consisted of open-grown coffee (OG), coffee partially shaded by rubber trees (PSH), and coffee fully shaded by rubber trees (FSH). The mapping of morphostructural features and soil resistance to penetration in “cultural profile” walls identified changes in soil structure resulting from different tillage systems. Root distribution was better in coffee plants grown in PSH and FSH systems. At greater depths, cultural profiles of FSH and PSH showed a larger numbers of roots compared to OG. Among the three systems, PSH provided a better environment for root growth and distribution. This result could be attributed to the high biological activity and interaction between roots and aggregates in that profile. The FSH agroforestry system provided less compact morphological structures and more roots throughout the soil profile. The agroforestry systems presented fewer soil structural changes by tillage operations and lower values of soil penetration resistance. Coffee root distribution was an effective indicator of soil quality and consistent with the morphostructural characterization of cultural profile.

Adsorption and degradation of the herbicide nicosulfuron in a stagnic Luvisol and Vermic Umbrisol cultivated under conventional or conservation agriculture

The main goals of conservation agriculture are to enhance soil fertility and reduce soil degradation, especially through erosion. However, conservation agriculture practices can increase the risk of contamination by pesticides, mainly through vertical transfer via water flow. Better understanding of their sorption and degradation processes is thus needed in conservation agriculture as they control the amount of pesticide available for vertical transfer. The purpose of our study was to investigate the sorption and degradation processes of nicosulfuron in soil profiles (up to 90 cm deep) of a Vermic Umbrisol and a Stagnic Luvisol managed either in conventional or in conservation agriculture. Two laboratory sorption and incubation experiments were performed. Low sorption was observed regardless of the soil type, agricultural management or depth, with a maximum value of 1.3 ± 2.0 L kg-1. By the end of the experiment (91 days), nicosulfuron mineralisation in the Vermic Umbrisol was similar for the two types of agricultural management and rather depended on soil depth (29.0 ± 2.3% in the 0-60-cm layers against 7.5 ± 1.4% in the 60-90 cm). In the Stagnic Luvisol, nicosulfuron mineralisation reached similar value in every layer of the conservation agriculture plot (26.5% ± 0.7%). On the conventional tillage plot, mineralisation decreased in the deepest layer (25-60 cm) reaching only 18.4 ± 6.9% of the applied nicosulfuron. Regardless of the soil type or agricultural management, non-extractable residue formation was identified as the main dissipation process of nicosulfuron (45.1 ± 8.5% and 50.2 ± 7.0% under conventional and conservation agriculture respectively after 91 days). In our study, nicosulfuron behaved similarly in the Vermic Umbrisol regardless of the agricultural management, whereas the risk of transfer to groundwater seemed lower in the Stagnic Luvisol under conservation agriculture.

Delineation of Soil Fertility Management Zones for Site-specific Nutrient Management in the Maize Belt Region of Nigeria

Site-specific nutrient management can reduce soil degradation and crop production risks related to undesirable timing, amount, and type of fertilizer application. This study was conducted to understand the spatial variability of soil properties and delineate spatially homogenous nutrient management zones (MZs) in the maize belt region of Nigeria. Soil samples (n = 3387) were collected across the area using multistage and random sampling techniques, and samples were analyzed for pH, soil organic carbon (SOC), macronutrients (N, P, K, S, Ca and Mg), micronutrients (S, B, Zn, Mn and Fe) content, and effective cation exchange capacity (ECEC). Spatial distribution and variability of these parameters were assessed using geostatistics and ordinary kriging, while principal component analysis (PCA) and multivariate K-means cluster analysis were used to delineate nutrient management zones. Results show that spatial variation of macronutrients (total N, available P, and K) was largely influenced by intrinsic factors, while that of S, Ca, ECEC, and most micronutrients was influenced by both intrinsic and extrinsic factors with moderate to high spatial variability. Four distinct management zones, namely, MZ1, MZ2, MZ3, and MZ4, were identified and delineated in the area. MZ1 and MZ4 have the highest contents of most soil fertility indicators. MZ4 has a higher content of available P, Zn, and pH than MZ1. MZ2 and MZ3, which constitute the larger part of the area, have smaller contents of the soil fertility indicators. The delineated MZs offer a more feasible option for developing and implementing site-specific nutrient management in the maize belt region of Nigeria.

Effect of Different Manure Sources on Soil Chemical Properties, Performance and Yield of Maize on a Degraded Land

Application of manure for soil amendment plays important roles in reclaiming and improving soil properties of degraded soils. This study assessed the effects of composted and non-composted manures on a degraded soil under continuous maize production. The treatments applied consisted of composted manures in form of cassava based compost (CBM) and verticompost (VC) at the rate of 0, 30, 60 and 120 tons/ha, non-composted manure (NC) applied as poultry manure (PM), and an un-amended control plot. These treatments were laid out in a randomized complete block design replicated three times. Soil physical and chemical properties were determined for two consecutive seasons, with maize (SUWAN 1-SYR) planted as test crop. The CBM, VC and PM treatments increased the soil organic carbon content by 18.2, 24.1, and 22.3 % respectively. Corresponding increases observed in cation exchange capacity (CEC) were 13.6, 15.7, and 15.2 %. The comparison of the soil chemical properties measured indicated positive effects from the amendments on the soil properties in the order: CBM < PM < VC. The maize grain yield of cassava based fertilized plot consistently and significantly was higher than the other treatments in both cropping seasons. However, both the composted and non-composted manures favored improved maize growth and resulted in higher grain yields (4.62 – 6.03 t ha-1) than the un-amended control treatment (3.69 t ha-1). The study therefore showed that the incorporation of manures, whether composted or non-composted, is beneficial to soils, improving one or more essential soil attributes thus reducing soil degradation.

How Do Newly-Amended Biochar Particles Affect Erodibility and Soil Water Movement?—A Small-Scale Experimental Approach

Biochar amendment changes chemical and physical properties of soils and influences soil biota. It is, thus, assumed that it can also affect soil erosion and erosion-related processes. In this study, we investigated how biochar particles instantly change erodibility by rain splash and the initial movement of soil water in a small-scale experiment. Hydrothermal carbonization (HTC)-char and Pyrochar were admixed to two soil substrates. Soil erodibility was determined with Tübingen splash cups under simulated rainfall, soil hydraulic conductivity was calculated from texture and bulk soil density, and soil water retention was measured using the negative and the excess pressure methods. Results showed that the addition of biochar significantly reduced initial soil erosion in coarse sand and silt loam immediately after biochar application. Furthermore, biochar particles were not preferentially removed from the substrate surface, but increasing biochar particle sizes partly showed decreasing erodibility of substrates. Moreover, biochar amendment led to improved hydraulic conductivity and soil water retention, regarding soil erosion control. In conclusion, this study provided evidence that biochar amendments reduce soil degradation by water erosion. Furthermore, this effect is detectable in a very early stage, and without long-term incorporation of biochar into soils.

Effects of Tillage Systems and Cropping Patterns on Soil Physical Properties in Mozambique

Conservation agriculture (CA) practices are advocated to reduce soil degradation, resulting in more sustainable food production as compared to conventional tillage (CT). In this study, the short-term effects of two tillage systems in combination with cropping patterns on selected soil physical parameters on four experimental sites in Mozambique were studied. The study sites differ according to their climatic conditions, soil types, and crop adaptation. Tillage systems evaluated were CA and CT, while the cropping pattern had four levels of sole cropping and three levels of intercropping. In general, soil physical properties showed significant changes due to the tillage systems, but the cropping pattern and their interaction with tillage systems did not yield significant impacts on the soil physical properties. CA increased bulk density, penetration resistance, and saturated hydraulic conductivity as compared to CT. A significant difference due to the tillage system was observed across the four sites, and in general, evaporation was higher in CT compared to CA. The presence of crop residues in CA contributed to lower evaporation. Thus, in the short term, CA practices could be a sustainable option to conserve soil water through higher infiltration and less evaporation.

Effects of Nitrogen fertilisation and stocking rates on soil erosion and water infiltration in a Brazilian Cerrado farm

Ever-increasing water-food-energy demand has led to the depletion of soil resources by mainly inadequate grazing practices. Nevertheless, the effects of different grazing practices on hydrological and soil erosion processes have not yet been well-understood. Therefore, we investigated the influence of different Nitrogen application doses and stocking rates in a pasture under rotational stocking (RS) on soil erosion and water infiltration in the Brazilian Cerrado region. The experimental area was a Panicum maximum pasture and was divided into three treatments with N applications of 100, 200, and 300 kg ha-1, which respectively allowed three stocking rates from 2014 to 2018: 3 (RS-3), 4.1 (RS-4), and 5 AU ha-1 (RS-5). We respectively adopted start and stop grazing heights of 80–90 and 40–50 cm (forage height) in all treatments. To evaluate infiltration and soil erosion, we performed 28 rainfall simulations with intensities ranging from 73.5 to 93.5 mm h-1 in plots of 0.7 m2 from November 2017 to February 2018. The simulations were carried out in random sites inside the central paddocks of each treatment comprising four repetitions in each treatment under vegetation and bare soil. We found stable water infiltration (SIR) and soil loss (SLw) ranging from 65.5 to 87.2 mm h-1 and from 0.03 to 0.15 mg s-1 m-2, respectively. SIR and SLw under RS-5 were respectively 33% greater and 78% lower than under RS-3 despite the 67% higher stocking rate in RS-5. We found that higher stocking rates at optimal grazing pressure did not deteriorate water infiltration and soil erosion. Our findings reveal an opportunity for a 5-fold productivity increase while reducing soil degradation since adaptive stocking rates are supported by grazing processes along with an increase in N fertiliser dose to increase vegetation cover.

Water and pesticide transfers in undisturbed soil columns sampled from a Stagnic Luvisol and a Vermic Umbrisol both cultivated under conventional and conservation agriculture

The main goals of conservation agriculture are to enhance soil fertility and to reduce soil degradation especially through erosion. However, conservation agriculture practices can exhibit a higher risk of contamination through vertical flows. The objectives of this study were to (i) characterise water and pesticide transfers in two different soils both managed under conventional and conservation agriculture and (ii) assess the effects of pesticide properties, soil type and agricultural system on pesticide fate. We studied the behaviour of two herbicides (nicosulfuron and mesotrione) and a molluscicide (metaldehyde) in percolation experiments in undisturbed soil columns. A series of two rain events (one with a high, the other with a low intensity) separated by a two-day flow interruption was applied three days after the pesticides and bromide application. Batch sorption coefficients, Kd, were also measured. While the Pesticides Properties Data Base (2020) indicated a decrease of sorption in the order mesotrione > metaldehyde > nicosulfuron, the measured Kd, decreased in the order mesotrione (2.3 ± 1.4 L.kg−1) > nicosulfuron (0.7 ± 0.4 L.kg−1) > metaldehyde (0.1 ± 0.1 L.kg−1). We highlighted distinct behaviour of pesticide leaching depending mainly on soil type, agricultural practices and pesticide properties. For low degree of preferential flow, pesticide leaching can be related to the sorption properties of pesticides. Nicosulfuron and mesotrione delays are more pronounced under conservation management while metaldehyde always arrived with no delay. During the high intensity rain event, on one soil type, high degree of preferential flow masked sorption effect on leaching since every pesticide arrived at the same time as the tracer and amounted to up to 21% of pesticide recovery compared to 4% on the other soil type. Conservation agriculture was found to improve the vertical transfers of water and pesticides while, on one of the studied soil type, the presence of a low conductive plough pan significantly limits water drainage.

Spatial Bayesian belief networks: a participatory approach for mapping environmental vulnerability at the Itatiaia National Park, Brazil

A Bayesian belief network (BBN) was implemented to assess environmental vulnerability in the Itatiaia National Park (INP). Information of soils, land use/cover, climate, relief and parent material was used to create the BBN, and the input nodes were those presumed as having a direct influence on the environmental vulnerability analysis. The literature review and a participatory approach were the basis to construct the structure of the network and to define the relations of dependence between the nodes through the conditional probability tables (CPTs). The most fragile areas were identified in soils with high organic carbon content, cation exchange capacity and fire susceptibility, low bulk density, low pH, poorly drained, profiles less developed, accentuated slopes, vegetation cover as altitude field and close to the trails or farms. Also, soils are formed from colluvial parent material. Despite the complexity of the study area, BBN was able to produce significant results. In addition to the BBN approach being less subjective than that conventionally used in vulnerability studies in Brazil, it was possible to obtain the propagation of the uncertainty associated with the prediction. The results will help decision makers to identify priority areas for intervention, reduce soil degradation in the highly vulnerable areas and help the INP managers in achieving a balance between nature conservation needs and recreational opportunity. Moreover, the BBN model may be updated as new knowledge or data are produced; and it can be used to support the process of the adaptive management plan.