Effects Of Conservation Practices Research Articles

Introduction pages, Nova Geodesia 4(1), 2024

Nova Geodesia (https://novageodesia.ro), Issue 1, Volume 4, 2024: The papers published in this issue represent interesting novelties in different topics of geodetic science or related fields. Nova Geodesia publishes significant papers in geodesy and close topics related to cartography, engineering projects and construction, planetology, hydrography, geography, sociodemographic factors, urban administration, planning and environment, landscape, biodiversity, and ecology. Among the exciting articles, we invite readers to find news about: Monitoring the evolution of a wetland pattern near Addis Ababa with the use of Landsat data (1986-2019); Effect of soil and water conservation practices and slope gradient on organic carbon stocks micronutrients: A case study on Kulkullessa sub-watershed, Eastern Ethiopia; The cross-disciplinary influence of aerial measurement techniques: Exploring archaeological studies through photogrammetry and LiDAR.

Effect of soil and water conservation practices and slope gradient on organic carbon stocks micronutrients: A case study on Kulkullessa sub-watershed, Eastern Ethiopia

Soil degradation in sub-Saharan Africa is a serious problem that causes declines in agricultural productivity linked to hunger and poverty. The study was conducted in the Kulkullessa sub-watershed of Goro Gutu District in Eastern Ethiopia to assess the effects of climate-smart soil and water conservation (SWC) practices and slope gradient on selected physicochemical properties of the soil and the soil’s organic carbon stocks. The farmland conserved by stone bund (SB), bench terrace (BT), and gras strip (GS) five years after construction with two slope gradients (15-20%) and (21-30%) was selected. Twenty-four composite soil samples were collected from a depth of 20 cm and tested in the Haramaya University soil laboratory. The study found that climate-smart SWC practices were very effective on the soil physicochemical properties and soil organic carbon stock (SOCS) of the study area. Similarly, the slope gradient brought considerable variation in soil physicochemical properties and soil organic carbon stock. On farmland that a bench terrace had preserved, the bulk density (BD) value was lower. The recorded value for total porosity on the farmland conserved by BT was also positively higher and significant (p ≤ 0.05). Likewise, the higher mean values for micronutrients and SOCS were recorded on farmlands conserved by SB, BT, and GS in contrast to the values recorded on non-conserved farmland (NCF) in the study area. Based on the study findings, climate-smart soil water and conservation practices have outstanding potential for improving soil physicochemical properties essential for agricultural crop production, climate change adaptation, and strengthening smallholder farmers’ resilience.

Effects of physical soil and water conservation practices and slope gradient on soil physicochemical properties in northwestern Ethiopia

Soil erosion is the major factor that has contributed to the reduction of soil fertility in the highlands of Ethiopia. This factor is reduced by soil and water conservation (SWC) practices. Hence, this study evaluated the effects of physical SWC practices and slope gradient on the soil physicochemical properties in the Agemi watershed of northwestern Ethiopia. Farmland treated by SWC such as stone-faced soil bund (SFSB) and soil bund (SB), untreated farmland (control), and slope gradient were identified in the study area. About 27 composite soil samples were collected from the treated farmland and untreated farmland with three slope classes, including lower (5–10%), middle (10–15%), and upper slopes (> 15%). Soil physicochemical properties were analyzed using the SAS 9.4 software following two-way ANOVA procedures. The results of the study showed that the content of sand, clay, total porosity, pH, soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP), cation exchange capacity (CEC), and exchangeable cations (Ca2+, Mg2+, K+) were affected (p < 0.05) by SWC practices and slope gradient. The SWC practices such as SFSB have a higher mean value of soil physicochemical properties than SB and untreated farmland. As a result, farmland treated by SFSB improves soil physicochemical properties by reducing soil erosion. Therefore, SFSB should be implemented on untreated farmland to improve soil fertility in the study area.

Local attitudes towards conservation governance in a large tropical multiple-use Marine Protected Area in Brazil

The attitudes of local residents living adjacent to Marine Protected Areas (MPAs) can influence the effectiveness of conservation management and practices, such as acceptance of the protected area rules and the willingness to participate in decision-making. Negative attitudes lead to non-compliance with environmental regulations, making it harder to achieve MPA management and governance objectives. However, the underlying drivers of negative attitudes to MPAs are complex, contextual, and generally poorly known. Here, we test to what extent social, economic, and political characteristics of stakeholders are associated with positive and supportive attitudes towards the implementation of good governance principles in one of Brazil's largest sustainable use MPAs. We conducted 331 face-to-face interviews with stakeholders from different social groups, applying a questionnaire exploring attitudes towards MPA governance based on Lockwood's governance principles. We found that educational level, income, sociopolitical engagement, and attendance at environmental meetings were all associated with positive attitudes towards principles of good MPA governance. Artisanal fishers, especially Shellfishers, generally had more negative attitudes towards governance principles. Good governance is critical for effective management, ensuring that decisions are made transparently and accountably, that stakeholders are engaged and involved in decision-making, efforts are coordinated and resources are used effectively, and that the legal framework is strong and enforced. Our findings highlight the importance of addressing underlying economic and educational inequalities among local stakeholders in addition to targeted environmental education.

Impact of conservation practices on soil quality and ecosystem services under diverse horticulture land use system

The 20-year study investigated the effects of conservation practices (CPs) and farmers' practices (FPs) on various soil quality parameters, yield, and economics of horticultural land use systems. CPs demonstrated significant improvements in soil organic carbon (SOC), available nitrogen (N), phosphorus (P), and potassium (K), compared to FPs. Horticultural systems exhibited higher SOC and available N and P contents than FPs, with substantial variations among different fruit species. CPs also enhanced soil quality index, functional diversity, culturable microbial populations, enzyme activity, and soil microbial biomass carbon (SMBC) compared to FPs. It was observed that the SMBC values were 25.0–36.6% and 4.12–25.7% higher in 0–15 cm and 15–30 cm, respectively, under CPs compared to FPs for all the land use systems. In CPs, dehydrogenase activities (DHAs) in surface soils were 9.30 and 7.50 times higher under mango- and citrus-based horticultural systems compared to FPs. The CPs adopted in aonla, guava, mango, litchi, and citrus-based horticultural systems increased SOC by ~27.6, 32.6, 24.4, 26.8, and 22.0%, respectively, over FPs. Canopy spread, fruit yield, litter yield, and soil moisture were significantly higher in fruit-based horticultural systems under CPs. Economic viability analysis indicated higher net present values (NPVs), benefit-cost ratio (BCR), and shorter payback periods (PBPs) for horticultural land use systems under CPs. Principal component analysis (PCA) revealed that CPs had a more positive influence on soil parameters, particularly DHA, acid and alkali phosphatase activity, available N, P, and K contents, soil microbial load, and organic carbon. The maximum ecosystem services were contributed through mango-based land uses among all land uses. Mango-based horticultural systems exhibited the least impact from both CPs and FPs, while peach-based systems were most affected by CPs. Overall, the findings highlight the benefits of conservation practices in improving soil quality, microbial populations, enzyme activity, and crop productivity in horticultural systems.

Effect of Moisture Conservation Practices on, Yield Attributes, Yield and Quality of Indian Mustard [Brassica juncea (L.) Czern&amp;Coss

A field experiment was carried out during two consecutive years (2016-17 and 2017-18) at Mahatma Gandhi Chitrakoot Gramodaya Vishwavidyala, Chitrakoot, Satna,(M.P.). Indiato evaluate the effect of moisture conservation practices on growth, yield attributes and yield of mustard under rainfed condition. Treatment consisted four moisture conservation practices i.e. no irrigation, life saving irrigation, straw mulch (Paddy straw @ 4t/ha) and kaolin 5 % spray. Result revealed that on pooled basis the tallest plant of 195 cm was recorded under life saving irrigation but number of branches (6.82) and dry weight per plant (39.8 cm) were significantly maximum in straw mulch treatment. The yield attributes such as siliqua per plant (298.5), seeds/siliqua (15.9), siliqua length (3.97 cm), seed weight per plant (17.06 g) and 1000- seed weight (5.57 g) were significantly superior under straw mulch followed by life saving irrigation. Significantly highest seed yield (2558 kg/ha), oil content (42.0 %) and protein content (20.5%) were obtained under straw mulch treatment while numerical enhancement was observed in life saving irrigation and kaolin 5% spray over no irrigation.

Impact of agro-geotextiles on soil aggregation and organic carbon sequestration under a conservation-tilled maize-based cropping system in the Indian Himalayas

Although agro-geotextile (AGT) emplacement shows potential to mitigate soil loss and, thus, increase carbon sequestration, comprehensive information is scanty on the impact of using agro-geotextiles on soil organic carbon (SOC) sequestration, aggregate-associated C, and soil loss in the foothills of the Indian Himalayan Region. We evaluated the impacts of Arundo donax AGT in different configurations on SOC sequestration, aggregate stability, and carbon management index (CMI) since 2017 under maize-based cropping systems on a 4% land slope, where eight treatment procedures were adopted. The results revealed that A. donax placement at 0.5-m vertical-interval pea–wheat (M + AD10G0.5-P-W) treatment had ∼23% increase in SOC stock (27.87 Mg·ha−1) compared to the maize–wheat (M-W) system in the 0–30-cm soil layer. M + AD10G0.5-P-W and maize–pea–wheat treatments under bench terracing (M-P-W)BT had similar impacts on SOC stocks in that layer after 5 years of cropping. The total SOC values in bulk soils, macroaggregates, and microaggregates were ∼24, 20, and 31% higher, respectively, in plots under M + AD10G0.5-P-W treatment than M-W in the topsoil (0–5 cm). The inclusion of post-rainy season vegetable pea in the maize–wheat cropping system, along with AGT application and crop residue management, generated additional biomass and enhanced CMI by ∼60% in the plots under M + AD10G0.5-P-W treatment over M-W, although M + AD10G0.5-P-W and (M-P-W)BT had similar effects in the topsoil. In the 5–15-cm layer, there was no significant effect of soil conservation practices on CMI values. Under the M + AD10G0.5-P-W treatment, the annual mean soil loss decreased by ∼92% over M-W treatment. We observed that CMI, proportion of macroaggregates, aggregate-associated C, labile C, total SOC concentration (thus, SOC accumulation rate), and mean annual C input were strongly correlated with the mean annual soil loss from 2017 to 2021. The study revealed that the emplacement of an A. donax mat and incorporation of a legume in a cropping system (M-W), conservation tillage, and crop residue retention not only prevented soil loss but also enhanced C sequestration compared to farmers’ practice (M-W) in the Indian Himalayas. The significance of this study is soil conservation, recycling of residues and weeds, and climate change adaptation and mitigation, as well as increasing farmers’ income.

Simulating synergistic effects of climate change and conservation practices on greenhouse gas emissions and crop growth in long-term maize cropping systems

Understanding the impacts of future climate change and long-term agronomic practices on environmental quality and agricultural productivity is critical to the development of sustainable agronomic management approaches. Given these requirements, the present study’s objective was to evaluate the potential impacts of climate change and long-term conservation practices on greenhouse gas (GHG) emissions and crop growth. To project potential future (2065–2084) climatic conditions for a field under a long-term maize cropping system situated in Nebraska (USA), 12 different combinations of regional climate models × global climate models (RCMs-GCMs) were generated under representative concentration pathway 8.5 (RCP8.5) and a heightened atmospheric carbon dioxide concentration ([CO2]atm = 714.1 ppm). Then, employing a well-calibrated instance of the Root Zone Water Quality Model (RZWQM2), the effects of four long-term conservation practices were simulated under the 12 RCMs-GCMs. Compared to other climatic factors (e.g., shortwave radiation, wind run, and relative humidity), temperature, precipitation, and [CO2]atm played more important roles for future carbon dioxide (CO2) and nitrous oxide (N2O) emissions, global warming potential (GWP), soil organic carbon (SOC), crop yield, and total crop biomass. The sum of their relative contributions to GHG emissions and crop growth exceeded 83.9 % across all treatments. Under future climatic conditions, CO2 and N2O emissions increased significantly — 19.4 % ± 5.8 % and 26.6 % ± 8.9 %, respectively — compared to those under historical baseline conditions. Likewise, the GWP increased by 19.8 ± 5.8 %. Although rising [CO2]atm afforded limited benefits in terms of crop photosynthesis rates, rising future temperatures shortened crop growth cycles, resulting in a net decrease of 9.1 % ± 1.9 % in maize yield and 4.2 % ± 1.6 % in total biomass. SOC saw a net increase of 4.8 % ± 0.4 % under the future (vs. baseline) climate. Compared to residue removal with no-till treatment, annual CO2 and N2O emissions in the long-term maize cropping system were predicted to increase by 26.8 % and 27.9 % between 2065 and 2084 under residue retention with tillage treatment, respectively. Whereas crop yield and biomass were not significantly affected by residue or tillage management practices. The simulation method provided valuable evidence for management decisions to assess the synergistic effects of climate change and long-term agronomic practices on the environment and agricultural productivity. Further investigation is needed on the effects of other climate RCPs and agronomic management for sustainable agricultural production.

Differential effects of soil conservation practices on arthropods and crop yields

AbstractMany agricultural management tactics, such as reduced tillage, aim to promote biodiversity and ecosystem services. Responses to such tactics can be context dependent, however, and differentially impact (i) functional groups of service‐providing organisms and (ii) crop yields. In canola (Brassica napus L., B. rapa L.) crop fields, we assessed how soil tillage and landscape context (amount of semi‐natural habitat within 1 km of each field) affected arthropod biodiversity and crop yield. We assessed effects of full (multiple tillage passes that leave soil surface bare), intermediate (tilled once and some stubble remains), or no (seed planted directly into last year's stubble) tillage on functional groups with unique diets and reproductive strategies: (i) herbivores, (ii) kleptoparasites, (iii) parasitoids, (iv) pollinators, and (v) predators. Effects of tillage and landscape context on arthropod abundance and diversity varied across functional groups. Pollinators responded strongest to tillage, benefitting from intermediate tillage. Predators and herbivores responded strongly to landscape context, as both were more abundant in landscapes with more semi‐natural habitat. Our results suggest that natural history differences among functional groups mediate effects of landscape context on biodiversity. However, variation in arthropod communities had little effect on canola crop yield. The effects of soil management practices on aboveground arthropods are complex, and practices thought to increase some aspects of agricultural sustainability may not be beneficial in other contexts. Identifying practices such as intermediate tillage that may increase soil quality and arthropod diversity is a key to designing agricultural ecosystems that will effectively benefit both biodiversity and human well‐being.

Effects of conservation practices on rainfed maize yield, furrow water infiltration, and soil moisture for surface sealing loam soils in the Yazoo‐Mississippi Delta

AbstractDecades of intense tillage have created the problem of surface sealing in loam soils across the Mid‐South United States and beyond. These soils exhibit low organic matter, poor aggregate stability, and ultimately low infiltration rates that decrease rainfed crop productivity and increase irrigation water demand. This research quantified the effects of soil management practices on rainfed maize (Zea mays L.) yield, furrow water infiltration, and soil moisture in Commerce very fine sandy loam and silt loam near Stoneville, MS. The six treatments included conventional tillage (CT), cereal rye (CR; Secale cereale L.), furrow diking (FD), no‐till (NT), polyacrylamide (PAM), and subsoiling (SS). No other treatment achieved a significantly higher maize grain yield than the CT control treatment in both years consistently. Single‐ring infiltrometer results indicated no significant differences among CT, CR, PAM, and SS in 2022 and between CT and NT in 2021. Neutron attenuation found that total soil water within the top 1 m was not significantly different among CT, FD, and SS on any of the eight measurement dates throughout the 2022 maize reproductive period. However, soil moisture was numerically lower for FD in the late reproductive stages. These findings suggest that environmental factors and other agronomic operations may counteract conservation practices, limiting their effectiveness at reducing irrigation requirements to mitigate groundwater depletion in the Mississippi River Valley Alluvial Aquifer.

An ecological networks approach reveals restored native vegetation benefits wild bees in agroecosystems

Conservation of species that rely on mutualistic partners such as pollinators are often better studied using interaction networks and indicators of ecological functions. We used a novel systems-ecology approach using network analysis and bee morphological traits to investigate ecological structure and bee body condition in the context of a conservation practice known as prairie strips established within row-crop fields compared to unrestored field margins. We found the increased flower resources in prairie strips produced a network supporting a greater chance for bee-mediated plant pollination. Some, but not all, bee groups showed improved body condition at prairie strip sites with variation due to taxonomic group, foraging preferences, and body size. This study supports a growing body of literature on the utility of network analysis in more broadly assessing the effect of conservation practices on ecological communities.

Effects of Soil and Water Conservation Practices and Slope Gradient on Selected Soil Physicochemical Properties in Ejersa Watershed, Toke Kutaye District, Ethiopia

This study was conducted to assess the effects of soil and water conservation practices and slope gradients on selected physicochemical properties of soil at Ejersa Watershed based on a total of 18 composite soil samples collected and analyzed using standard laboratory procedures. The values of pH, electrical conductivity, cation exchangeable capacity, organic carbon, organic matter, total nitrogen, and available phosphorus determined in soil samples collected from conserved and nonconserved plots were 6.4 and 6.16, 40.26 mS/m and 15.12 mS/m, 33.51 meq/100 g and 21.56 meq/100 g, 2.66% and 2.24%, 4.58% and 3.86%, 0.24% and 0.15%, and 29.45 ppm and 17.68 ppm, respectively. Soil pH, electrical conductivity, moisture, total nitrogen, and available phosphorus were significantly different ( p &lt; 0.01 ) between treated and untreated plots and among the slope classes. Values of soil organic carbon and organic matter showed significant differences ( p &lt; 0.05 ) between land types but not among the slope classes. Soil cation exchange capacity showed significant difference ( p &lt; 0.05 ) between land types as well as among the slope classes. Relatively, higher values of many of the physicochemical parameters were recorded in samples collected from the treated land and lower slopes which might be attributed to the deposition effects of the conservation practices and decline in the rate of soil erosion.

Tied ridging enhances soil water conservation and productivity of common bean (&lt;i&gt;Phaseolus vulgaris&lt;/i&gt;)

A field trial was conducted to determine the effects of different water conservation practices done in-situ on soil water content, stomatal conductance, and seed yield of common beans at Fumesua experimental station of the CSIR-Crops Research Institute in Ghana during the 2020 and 2021 cropping seasons. The water conservation practices implemented were tied ridges (TR), bunded basins (BB), and flat land (FL). Results showed that the TR treatment increased soil water content by 18 and 16% (0-5 cm), 12 and 13% (5-10 cm), and 18 and 7% (10-30 cm), compared with the FL treatment in 2020 and 2021 respectively. Across years, TR treatment increased stomatal conductance by 39 and 53% at both vegetative and flowering sampling periods. Soil water content and stomatal conductance also increased in the BB treatment compared to the FL treatment, but to a lesser extent than that of TR. The TR treatment improved seed yield by 31 and 42% over that of FL in 2020 and 2021, respectively. At a lesser magnitude, the BB treatment increased seed yield by 17 and 40% compared with the FL treatment during the same period. These results showed a positive relationship (p &lt; 0.05) between the soil water content and common beans seed yield, such that an increase in soil water content determined about 75% of the increase in seed yield. Based on the results of this study, tied ridging could be considered a suitable water conservation strategy for improving common bean yield.

Are we saving water? Simple methods for assessing the effectiveness of groundwater conservation measures

Substantial storage reductions by irrigation pumping in many of the world’s major aquifers jeopardize future food production. As a result, new conservation measures are being utilized to reduce pumping and extend aquifer lifespans. The key question is how effective are these practices in attaining true water conservation (i.e., water use reduction) for a given area? Relationships between pumping and precipitation help provide an answer, as precipitation explains most of the variation in annual irrigation water use for aquifers in semi-arid to sub-humid climates when surface water supplies are limited. Our objective is to utilize correlations between radar precipitation and irrigation groundwater use at a range of spatial scales to assess the effectiveness of conservation approaches in the High Plains aquifer in the central USA. Linear regressions between pumping and precipitation for a conservation area established in 2013 in northwest Kansas indicate that water use and water use per irrigated area were over 27 % less and 25 % less, respectively, during 2013–2021 compared to the same climatic conditions during 2005–2012. Similar regressions found over a 38 % reduction and 23 % reduction in irrigation water use and use per irrigated area, respectively, during 2018–2021 compared to the same conditions during 2005–2017 in a west-central Kansas county with conservation areas. A decrease in irrigated area accounted for most of the difference between these reductions. Higher R2 values after conservation area establishment imply that irrigation tracks precipitation better due to use of soil moisture sensors and other measures as part of increased irrigation efficiency and enhanced water management. The precipitation and water use relationships, which are statistically significant for a wide range of spatial scales, have great potential for assessing the effectiveness of conservation practices in areas with high-quality water use and precipitation data.

Carbon Storage in Cropland Soils: Insights from Iowa, United States

The restoration of soil organic matter (SOM, as measured by soil organic carbon (SOC)) within the world’s agricultural soils is imperative to sustaining crop production and restoring other ecosystem services. We compiled long-term studies on the effect of management practices on SOC from Iowa, USA—an agricultural region with relatively high-quality soil data—to highlight constraints on detecting changes in SOC and inform research needed to improve SOC measurement and management. We found that strip-tillage and no-tillage increased SOC by 0.25–0.43 Mg C ha−1 yr−1 compared to losses of 0.24 to 0.46 Mg C ha−1 yr−1 with more intensive tillage methods. The conversion of cropland to perennial grassland increased SOC by 0.21–0.74 Mg C ha−1 yr−1. However, diversifying crop rotations with extended rotations, and supplementing synthetic fertilizer with animal manure, had highly variable and inconsistent effects on SOC. The improved prediction of changes in SOC requires: the use of methods that can identify and disentangle multiple sources of variability; looking beyond total SOC and toward systematic collection of data on more responsive and functionally relevant fractions; whole-profile SOC monitoring; monitoring SOC in long-term studies on the effect of multiple conservation practices used in combination; and deeper collaboration between field soil scientists and modelers.

Effects of soil and water conservation practices and landscape position on soil physicochemical properties in Anuwa watershed, Southern Ethiopia

Ethiopia's main environmental problem has been soil erosion. To control and reverse the problem, soil and water conservation (SWC) techniques have been deployed over the past two to three decades. The purpose of this study is to evaluate the effect of implemented soil and water conservation measures on soil physicochemical properties in the Anuwa watershed, southern Ethiopia, under various conservation structures (Soil bund, Fanya Juu, Stone bund and Micro Basin) and topographic positions (upper, middle and lower) of conserved plots. The soil samples were collected from 45 locations to analyze topsoil texture, bulk density (ρd), pH, soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP), CEC, exchangeable Na+, K+, Ca2+, and Mg2+. All soil samples were analyzed using standard and recommended methods. Using the SPSS computer program 21, the effect of independent variables (SWC practices and landscape position) on the dependent variables (soil properties) was statistically tested. The significance test was performed using two-way ANOVA. The findings indicated that the SWC measure significantly decreases the percent values of sandy soil texture, while it increased the mean values of organic carbon, available phosphorus, exchangeable Na+, K+, Ca2+, Mg2+, and CEC (P < 0.05). The sand content, the bulk density, the SOC, and the total nitrogen showed statistically significant variations between the conserved and non-conserved upper topography (P < 0.05). The effects of conservation measures were significant in almost all soil physicochemical properties at P < 0.01 except for the silt content, bulk density, and Ca2+ in the lower topography. The study findings revealed that Fanya Juu SWC measures are by far the most efficient, and recommended method to minimizing soil erosion, and improving selected soil physical and chemical quality in the Anuwa watershed. Local governments and other stakeholders should work cooperatively to strengthen and sustain the implementation process.

Combined impact of no-tillage and cover crops on soil carbon stocks and fluxes in maize crops

Soil plays a major role in the carbon cycle for both carbon stocks and respiration since soil organic carbon (SOC) is the most important carbon pool and soil CO2 efflux is the largest source of carbon emissions to the atmosphere. The aim of this study was to understand how the combination of no-till (NT) and cover cropping (CC) influences both SOC and soil respiration. Soil respiration was measured in southwestern France from April to October at two distinct sites characterized by contrasting initial soil carbon contents. Each site included two adjoining maize fields in which conservation (NT+CC) and conventional (CT) practices were used. For soil with initial high SOC contents (> 50 tC ha-1 in the 0–30cm layer), SOC stocks at the 0–90 cm depth (NT+CC: 72.4 ± 10.6, CT: 68.9 ± 9.2 t C ha-1) and respiration during the maize growing season (NT+CC: 0.57 ± 0.24, CT: 0.54 ± 0.26 g CO2 m-2 h-1) were not significantly different for both practices. For soil with initial low SOC contents, SOC stocks at the 0–90 cm depth (NT+CC: 42.7 ± 5.5, CT: 29.7 ± 4.8 t C ha-1) and respiration (NT+CC: 0.86 ± 0.32, CT: 0.50 ± 0.34 g CO2 m-2 h-1) were higher with the NT+CC practices than with the CT practices. Due to higher cover crop biomass and root density, SOC mineralization and root respiration were enhanced. We showed a positive effect of conservation practices on the SOC stock in the upper layers but also in the deeper layers (60–90 cm) only in a low initial carbon content environment. At high SOC levels, the soil may have reached its carbon sequestration potential, or the time since practices were implemented was not long enough to observe the effects. Our study shows that the potential of NT+CC to sequester large amounts of SOC, enabling the mitigation of greenhouse gas emissions, strongly depends on initial SOC contents.

Effects of conservation practices on global wind erosion control: Evidence from experimental data

AbstractWind erosion represents one of the major land degradation forms that significantly threatens sustainable development across the globe. A series of conservation practices have been widely developed and tested in order to effectively reduce wind erosion rates in non‐irrigated dry and semi‐dry lands. However, a comprehensive investigation regarding the efficacy of conservation practices and potential impacting factors on erosion control at the global scale has not been undertaken. In this study, a synthesis was conducted, based on data from global experimental plots, to comprehensively examine the efficacy of varying conservation practices, and their effectiveness at reducing erosion, in different geographical regions, under varying climatic conditions, and with different soil properties. The results showed that conservation practices were able to reduce wind erosion rates by over 52% globally. Straw use and soil stabilizer were the most effective measures in wind erosion control, which could reduce erosion rates by over 70%. Wind erosion control efficacy of conservation practices differed among climatic zones, continents, and countries. Notably, the lowest efficacy was observed in dry climatic zones. Erosion control efficacy highly depended on climatic conditions, such as mean annual precipitation (MAP), mean annual temperature (MAT), wind speed, and soil properties, such as water content and clay content. We further observed a positive correlation between wind erosion reduction rates and straw mulching rates, suggesting a straw mulching rate of at least 40% was necessary in order to reach a potential erosion reduction rate of 70%. To sum up, this study illustrates that the overall efficacy of conservation practices in wind erosion control is highly effective at the global scale, but the specific effects vary among different regions, and depend on conservation practice type, climatic condition, and soil property. The lower erosion reduction rate of dry regions at high erosion risk suggests the high erosion control pressure, and more effective measures should be considered and developed. The results of this study are, importantly, complementary to existing wind erosion control guidelines.

Ground beetles suppress slugs in corn and soybean under conservation agriculture.

Conservation agriculture practices such as eliminating tillage and planting high residue cover crops are becoming increasingly important in field crop systems in the US Mid-Atlantic. However, these practices have sometimes been associated with an increase in moderate to severe damage to field crops by slugs. Conserving natural enemy populations is a desirable way to manage slug infestations because remedial control measures are limited. Here, we tested the effects of conservation practices, weather, and natural enemies on slug activity-density measured by tile traps placed among 41 corn and soybean fields during the spring of 2018 and 2019 in the Northern Shenandoah Valley, Virginia, USA. We found that a positive effect of cover crops on slug activity-density was reduced by tillage and that slug activity-density declined with increasing ground beetle activity-density. Slug activity-density also declined with decreasing rainfall and increasing average temperature. Weather was the only significant predictor of ground beetle activity-density, which was reduced in sites and weeks that were relatively hot and dry or that were cool and wet. However, we also found a marginally significant negative effect of pre-plant insecticides on ground beetles. We suggest that the observed interacting effects of cover crops and tillage reflect favorable conditions for slugs provided by increased small grain crop residue that can be mitigated to some extent by even low levels of tillage. More broadly, our study suggests that implementation of practices known to promote recruitment of ground beetles in crop fields can improve natural suppression of slugs in corn and soybean that are being increasingly cultivated according to conservation agriculture practices.

Estimated reduction of nitrogen in streams of the Chesapeake Bay in areas with agricultural conservation practices

Spatial data provided by the U.S. Department of Agriculture National Resource Conservation Service representing implementation at the field-level for a selection of agricultural conservation practices were incorporated within a spatially referenced regression model to estimate their effects on nitrogen loads in streams in the Chesapeake Bay watershed. Conservation practices classified as “high-impact” were estimated to be effective (p = 0.017) at reducing contemporary nitrogen loads to streams of the Chesapeake Bay watershed in areas where groundwater ages are estimated to be less than 14-years old. Watershed-wide, high-impact practices were estimated to reduce nitrogen loads to streams by 1.45%, with up to 60% reductions in areas with shorter groundwater ages and larger amounts of implementation. Effects of “other-impact” practices and practices in areas with groundwater ages of 14 years or more showed less evidence of effectiveness. That the discernable impact of high-impact practices was limited to areas with a median groundwater age of less than 14 years does not imply that conservation practices are not effective in areas with older groundwater ages. A model recalibrated using high-impact agricultural conservation practice data summarized by county suggests effects may also be detectable using implementation data available at such coarser resolution. Despite increasing investment, effects of agricultural conservation practices on regional water quality remain difficult to quantify due to factors such as groundwater travel times, varying modes-of-action, and the general lack of high-quality spatial datasets representing practice implementation.