Annual Crop Fields Research Articles

Newly established, multifunctional woody polycultures preserve agroforestry soil health benefits of a widespread U.S. land retirement program

Soil health degradation within intensively managed annual crop systems threatens the long-term economic sustainability of maize- and soybean-dominated production regions like the U.S. Corn Belt. While Conservation Reserve Program (CRP) efforts to perennialize portions of farmland to improve soil health have been largely successful, many landowners intend to return CRP land to high revenue maize and soybean cultivation. The CRP could be a pathway for a regionally tailored and profitable form of agroforestry focused on fruit and nut production potential, known as multifunctional woody polycultures (MWPs). In theory, MWPs should provide similar soil health benefits as CRP agroforestry, as soil health benefits are generally robust across agroforestry practices. We conducted a study in the heart of the U.S. Corn Belt to compare soil health responses between newly established (<10 years) CRP and MWP agroforestry systems and adjacent annual crop production fields. Because organic inputs from plant litter and roots are more consistent under untilled perennial vegetation systems compared to intensively managed annual crop systems, we hypothesized that CRP and MWP would entail similar enhancements to physical, soil organic matter (SOM), and biological soil health. Our results indicate establishing untilled, perennial CRP and MWP systems can quickly improve physical and biological soil health relative to annual crop production, based on decreased soil bulk density, greater soil water infiltration, and increased soil enzyme activity. Unexpectedly, CRP and MWP elicited divergent SOM responses. Notably, only MWP increased surface soil organic carbon stocks relative to annual crop fields, likely reflecting species-variant plant biomass growth rates. Our study demonstrates MWPs can manifest similar improvements to physical and biological soil health as CRP agroforestry on a relatively short timescale. The sensitivity of transition-state SOM responses between CRP and MWP demonstrates the importance of woody perennial selection to maximize specific soil health outcomes.

Phosphorus fractions and speciation in an alkaline, manured soil amended with alum, gypsum, and Epsom salt.

Snowmelt runoff is a dominant pathway of phosphorus (P) losses from agricultural lands in cold climatic regions. Soil amendments effectively reduce P losses from soils by converting P to less soluble forms; however, changes in P speciation in cold climatic regions with fall-applied amendments have not been investigated. This study evaluated P composition in soils from a manured field with fall-amended alum (Al2(SO4)3·18H2O), gypsum (CaSO4·2H2O), or Epsom salt (MgSO4·7H2O) using three complementary methods: sequential P fractionation, scanning electron microscopy with energy-dispersive X-rays (SEM-EDX) spectroscopy, and P K-edge X-ray absorption near-edge structure spectroscopy (XANES). Plots were established in an annual crop field in southern Manitoba, Canada, with unamended and amended (2.5 Mg ha-1) treatments having four replicates in 2020 fall. Soil samples (0-10cm) taken from each plot soon after spring snowmelt in 2021 were subjected to P fractionation. A composite soil sample for each treatment was analyzed using SEM-EDX and XANES. Alum- and Epsom salt-treated soils had significantly greater residual P fraction with a higher proportion of apatite-like P and a correspondingly lower proportion of P sorbed to calcite (CaCO3) than unamended and gypsum-amended soils. Backscattered electron imaging of SEM-EDX revealed that alum- and Epsom salt-amended treatments had P-enriched microsites frequently associated with aluminum (Al), iron (Fe), magnesium (Mg), and calcium (Ca), which was not observed in other treatments. Induced precipitation of apatite-like species may have been responsible for reduced P loss to snowmelt previously reported with fall application of amendments.

A comprehensive update on the morphology and distribution of the invasive scaffold-web spider Eidmannella pallida (Araneae, Nesticidae) with a focus on new records from Italy.

Updated non-native distributional data of the invasive spider Eidmannella pallida (Emerton, 1875), Nesticidae, are herein summarized together with the morphological characters of the species. We report all the known localities from the literature. Furthermore, we present and discuss recent findings for the Italian peninsula. In particular, the species has been consistently found in vineyards and annual crop fields in North Italy and in olive groves in South Italy. We include a redescription of the species, and detailed illustrations of the diagnostic characters of both males and females, based on stereomicroscope and SEM images. The spreading potential of the species and its possible impacts on local communities are discussed. Our data suggest that E. pallida has high invasiveness potential and several new findings in non-native areas were recorded in the last years. We found that E. pallida can establish permanent populations in crop-dominated landscapes and has a tendency to exploit vulnerable ecosystems such as the subterranean environment. We thus recommend new and more comprehensive studies on this species to investigate in deeper detail its phylogeny, ecology, and micro-habitat preferences. A high effort should be placed to assess the potential negative effects of E. pallida on the endemic fauna in invaded areas, especially in caves.

Responses of Deep Soil Carbon and Nitrogen Contents to Long-Term Retention of Alfalfa Pasture on Infertile Loess: A Synthesis Study

Incorporating perennial pastures into annual crop systems is an efficient means of improving soil carbon (C) sequestration and reducing the application of nitrogen (N) fertilizer on farmlands. How the soil C and N at different soil depths respond to the length of pasture duration and rainfall conditions is still being determined. In this study, we conducted a meta-analysis of data from 63 published studies to investigate the impacts of the alfalfa pasture on the incorporation of soil organic carbon (SOC), total nitrogen (STN), and available nitrogen (SAN) contents in the 0–300 cm soil profile of the Loess Plateau. An annual crop field was taken as a reference. The results showed that the average SOC content at soil depths of 0–100 and 100–200 cm in the alfalfa pasture increased by 17% and 8% (p &lt; 0.001) compared to the crop field, respectively, while that at 200–300 cm decreased (p &gt; 0.05). The SOC content increased with pasture age; it was the highest when the alfalfa had been planted for 5–9 years and decreased thereafter. The STN content at soil depths of 0–100 and 100–200 cm increased by 19% and 14% (p &lt; 0.001), respectively; the content at depths of 200–300 cm only increased slightly (p &gt; 0.05). It also increased the most when the alfalfa was 5–9 years old. The increments in the SAN content at the 0–100 and 100–200 cm soil depths were higher than those of the STN, with values of 29% and 18%, respectively, while those at depths of 200–300 cm also changed insignificantly (p &gt; 0.05). The SAN content continuously increased with the age of the alfalfa, and the average increment in the 0–300 cm profile was as high as 21% when the alfalfa was ≥10 years old. The SOC and STN content increased the most under moderate rainfall conditions (350–500 mm), while the SAN content maintained the highest increment under high rainfall (500–650 mm) conditions. Therefore, ley farming with the alfalfa pasture contributed substantially to the soil C and N at depths of 200 cm in deep loess. Alfalfa should be removed in its middle ages to increase C sequestration while utilizing soil N efficiently.

Modeling of total and active organic carbon dynamics in agricultural soil using digital soil mapping: a case study from Central Nova Scotia

Monitoring the changes in soil organic carbon (SOC) pools is critical for sustainable soil and agricultural management. This case study models total and active organic carbon dynamics (2015/2016 to 2019/2020) using digital soil mapping (DSM) techniques. Model predictors include topographic variables generated from light detection and ranging data; soil and vegetation indices derived from Landsat satellite images; and soil and crop inventory information from Agriculture and Agri-Food Canada to predict total organic carbon (TOC) and permanganate oxidizable carbon (POXc) at the 0–15 cm depth increment for a 37 km2 study area in Truro, Nova Scotia. Quantile Regression Forest and stochastic Gradient Boosting Model were utilized for prediction. Although both models performed equally well for predicting TOC and POXc, the accuracy of TOC predictions (e.g., concordance correlation coefficient (CCC) = 0.67) was better than POXc predictions (e.g., CCC = 0.53). The Landsat variables and crop inventory were dominant predictors, while topographic variables across the relatively homogeneous terrain had relatively little influence. During the study period, changes in POXc were predicted across 98% of the study area, with a mean absolute loss of 5.77 (±11.48) mg/kg/year, and in TOC on 27% of the area, with a mean absolute loss of 0.15 (±0.09) g/kg/year. While the annual crop fields observed the highest loss of TOC and POXc, the decline in pasture–grassland–forage fields was relatively low. The study reinforced the effectiveness of DSM for modeling multiple SOC pools at the farm to landscape scales.

Linear Relationship of a Soil Total Water Potential Function and Relative Yield—A Technique to Control Salinity and Water Stress on Golf Courses and Other Irrigated Fields

A simple empirical approach is proposed for the determination of crop relative yield (%) through the soil total water potential (kPa). Recurring to decimal logarithms, from analytical exponential expressions, a linear simple relationship of soil total water potential Ψt (matric Ψm + potential Ψo) function and crop relative yield was studied and developed. The combination of the salinity model, the soil water retention model and the matric potential approach were used to reach this objective. The representation of turfgrass crop relative yield (%) versus a function of soil total water potential f(Ψt) values was shown through a log-normal graph (y = a + mx); the log scale axis “y” (ordinates) defines relative yield Yr, being two the origin ordinate “a” and “m” the slope; the normal decimal scale axis “x” (abscissa) is the function of soil total water potential f(Ψt). Hence, it is possible, using only two experimental points, to define a simple linear relation between a function of soil total water potential and crop relative yield, for a soil matric potential value lower than −20 kPa. This approach was first tested on golf courses (perennial turfgrass fields), but it was further decided to extend it to other annual crop fields, focused on the model generalization. The experimental plots were established, respectively, in Algarve, Alentejo and Oeiras (Portugal) and in the North Negev (Israel). Sprinkler and trickle irrigation systems, under randomized blocks and/or water and salt gradient techniques, were used for water application with a precise irrigation water and salt distribution. Results indicated that there is a high agreement between the experimental and the prediction values (R2 = 0.92). Moreover, the precision of this very simple and easy tool applied to turfgrass fields and other irrigated soils, including their crop yields, under several different sites and climatic conditions, can contribute to its generalization.

More milkweed in farmlands containing small, annual crop fields and many hedgerows

Milkweed has declined substantially, with over 80% declines in some agricultural regions. This threatens monarch butterfly (Danaus plexippus) persistence, because monarch larvae feed solely on milkweed. Thus conservation actions are needed to enhance the availability of milkweed, particularly in agricultural landscapes. Conservation actions to date have largely focused on reducing intensive agricultural practices, mainly use of herbicides. However, research suggests that landscape-scale alteration of the cropped portion of an agricultural landscape (the "farmland"), for example, to reduce crop field sizes, can benefit herbaceous plants such as milkweed. Here we collected data on milkweed occurrence and cover in agricultural landscapes in Ontario, Canada, capturing variability in milkweed from field edge to interior by sampling in the interior and along the edges of 68 crop fields. We used these data to evaluate the relative effects of farming practices within the sampled field (e.g. herbicide, fertilizer use) on milkweed versus the effects of mean field size, crop diversity, hedgerow cover, and the proportion of farmland in annual crops in the surrounding landscape. Additionally, we evaluated the effects of these variables on the cover of other herbaceous plants, to identify which—if any—could benefit milkweed without increasing overall weed cover. We found more milkweed at sites surrounded by landscapes with smaller crop fields, lower crop diversity, and higher cover of annual crops. Milkweed was more likely to occur at sites surrounded by landscapes with more hedgerows. These landscape-scale effects on milkweed were often larger than those of within-field farming practices. Importantly, we found that most variables had opposite effects on milkweed relative to other plants. Thus, altering the landscape to benefit milkweed does not imply an increase in weed cover.

Profiles and interrelationships of functional soil microbiomes involved in phosphorus cycling in diversified agricultural land‐use systems

AbstractSoil microbiomes play important roles in both transformation and utilization of phosphorus (P) in agroecosystems. By targeting at 18S rRNA, pqqC, and phoD genes, respectively, the community compositions of soil arbuscular mycorrhizal (AM) fungi and inorganic P‐solubilizing and organic P‐mineralizing prokaryotes were investigated across fields with annual crops or vegetables and orchards with peach trees or tea bushes in a common Agri‐technology Park, representing four typical agricultural land‐use types in Eastern China. Both annual crop and vegetable fields exhibited higher soil fertility and phosphatase activity, while both peach tree and tea bush orchards contained greater abundances of AM fungal and pqqC genes. Land‐use type also significantly affected the community compositions of soil AM fungi, and pqqC‐ and phoD‐harboring prokaryotes, with soil available P as the common driver for all functional groups above. Three main ecological clusters (modules) with distinctive interactive features, that is, synergistic, competitive, and inactive were observed in the co‐occurrence network comprised of the three groups involved in P‐cycling. The modules exhibited various distributions among the four land‐use types, and the correlations with soil pH, available P and K, and N:P were shown. Altogether, the results demonstrated the changes in gene abundances, diversity indices, community compositions, and interrelationships of functional groups involved in P‐cycling in response to distinct land‐use types, and highlighting the synergistic potential among groups to alleviate P deficiency.

Effect of the water regime, crop rotation and fertilizers in biogenic matters leaching into ground water and surface water

The purpose of our work was to establish features of formation of filtration processes and to define prevention measures towards the nutrients leaching from drainage soils into the ground waters. Our researches were carried out on typical drained floodplain soils of Panfil Research Station, Institute of Agriculture of National Academy of Agrarian Science (floodplain of Supiy River, Yahotyn district, Kiev region, Ukraine) in 2016-2018. The arable layer of peatlands had high level of decomposition (50-60%) with gross nitrogen contamination of 1.9%, phosphorus

Conservation potential of shade-tolerant forest species in agricultural mosaics in the eastern Brazilian Amazon

ABSTRACT Shade-tolerant forest species are among the most susceptible to habitat loss in agricultural mosaics, where a variety of croplands is connected to forests at different levels of anthropogenic disturbance. We aimed to evaluate the community similarity of shade-tolerant species among different land use types across agricultural mosaics with different levels of disturbance. The study was conducted in three municipalities in southern and southeastern Pará state, in eastern Amazonia. A multiple-community similarity measure based on the Horn similarity index was used to compare land use types and assess the resilience of shade-tolerant species towards forest loss and disturbance at the landscape level. High shade-tolerant species similarity was found between mature forest fragments that underwent different levels of disturbance in all three agricultural mosaics, but secondary forests had lower similarity with mature forest in the most fragmented and altered mosaic. Shade-tolerant species showed very low density in croplands, but the same group of species seemed to colonize agricultural fields of annual crops and clean pasture, as they showed high community similarity. Another group of species was present in invaded pastures, probably due to the effects of time since land abandonment after woody species colonization. Mixed tree plantations were more similar to mature and secondary forests than other types of croplands. Shade-tolerant species similarity was higher among land use types inserted in agricultural landscapes that maintained conserved forest fragments. Our results suggest that the conservation of mature forests and landscape connectivity are crucial to the maintenance of shade-tolerant species in agricultural mosaics.

Land Cover Mapping and Change Analysis in Tropical Humid-highlands: Case of Ndakaini Water Reservoir in Central Kenya

We successfully used optical remote sensing approach to test the skills of post-classification change detection technique as well as techniques of circumventing the challenges of cloud/cloud-shadow contamination and of working in a data-scarce environment in tropical humid highlands. The aim was to generate an accurate estimate of current land cover distribution map and analyze land-cover change around Ndakaini area in Kenya. Landsat imageries (TM and ETM + ) acquired between 1985 and 2011 and corresponding to the study area was selected. Employing bands 3 and 4 of respective Landsat images, thresholding techniques, Boolean and masking operations were implemented in detecting cloud/cloud-shadows and subsequent removal and filling of gaps. In absence of other historical ancillary data about land cover types, a total of 278 points across the study area were captured from Google Earth and used to evaluate the accuracy of each of the generated land cover maps. From the results, cloud/cloud-shadow gaps were reduced immensely (e.g. 90% for the 1985 image and 82% for the 2011 image). With regard to quality of classification outputs, the respective land cover/land-use maps of 2000, 2005 and 2010 anniversaries had fairly high level of overall accuracy (64%, 79% and 68% respectively) and Kappa statistic (0.47, 0.69 and 0.53 respectively) while classification outputs of 1985 and 1995 yielded slightly lower overall accuracy (60%) and Kappa statistic (0.42). Post-classification change involving three land cover classes, tea plantation, forest/woodlot and annual crop fields denoted as others were successfully determined and conclusions based on trend analysis drawn. The satisfactory results of this study imply the usefulness of post-classification change detection method in generating information about land cover dynamics in tropical humid highlands especially when coupled with robust techniques that adequately circumvent the cloud and cloud-shadow problem and scarcity of ancillary data often common in these areas. Keywords : Post-classification change detection, thresholding and Boolean techniques, landcover change, tropical humid-highlands DOI: 10.7176/JNSR/10-8-03 Publication date: April 30 th 2020

The impacts of agroforestry on agricultural productivity, ecosystem services, and human well-being in low-and middle-income countries: An evidence and gap map.

The impacts of agroforestry on agricultural productivity, ecosystem services, and human well-being in low-and middle-income countries: An evidence and gap map.

Effects of farmland heterogeneity on biodiversity are similar to—or even larger than—the effects of farming practices

Pressure to increase food production to meet the demands of a growing human population can make conservation-motivated recommendations to limit agricultural expansion impractical. Therefore, we need to identify conservation actions that can support biodiversity without taking land out of production. Previous studies suggest this can be accomplished by increasing “farmland heterogeneity”—i.e. heterogeneity of the cropped portions of agricultural landscapes—by, for example, decreasing field sizes. However, it is not yet clear whether policies/guidelines that promote farmland heterogeneity will be as effective as those targeting farming practices. Here, we estimated the relative effects of six practices—annual/perennial crop, fertilizer use, herbicide use, insecticide use, tile drainage, and tillage—versus two aspects of farmland heterogeneity—field size and crop diversity—on the diversity of herbaceous plants, woody plants, butterflies, syrphid flies, bees, carabid beetles, spiders, and birds in rural eastern Ontario, Canada. The strength of effect of farming practices and farmland heterogeneity varied among taxonomic groups. Nevertheless, we found important effects of both farming practices and farmland heterogeneity on the combined (multi) diversity across these groups. In particular, we found greater multidiversity in untilled, perennial crop fields than tilled, annual crop fields, and greater multidiversity in agricultural landscapes with smaller crop fields and less diverse crops. The directions of effect of these variables were generally consistent across individual taxonomic groups. For example, richness was lower in landscapes with larger fields and more diverse crops than in landscapes with smaller fields and less diverse crops for all taxa except spiders. The negative effect of crop diversity on multidiversity and the richness of most of the studied taxa indicates that this aspect of farmland heterogeneity does not necessarily benefit wildlife species. Nevertheless, a compelling implication of this study is that it suggests that policies/guidelines aimed at reducing crop field sizes would be at least as effective for conservation of biodiversity within working agricultural landscapes as those designed to promote a wildlife-friendly farming practice.

Contrasting Physiological and Environmental Controls of Evapotranspiration over Kernza Perennial Crop, Annual Crops, and C4 and Mixed C3/C4 Grasslands

Perennial grain crops have been suggested as a more sustainable alternative to annual crops. Yet their water use and how they are impacted by environmental conditions have been seldom compared to those of annual crops and grasslands. Here, we identify the dominant mechanisms driving evapotranspiration (ET), and how they change with environmental conditions in a perennial Kernza crop (US-KLS), an annual crop field (US-ARM), a C4 grassland (US-KON), and a mixed C3/C4 grassland (US-KFS) in the Central US. More specifically, we have utilized the omega (Ω) decoupling factor, which reflects the dominant mechanisms responsible for the evapotranspiration (ET) of the canopy. Our results showed that the US-ARM site was the most coupled with the lowest decoupling values. We also observed differences in coupling mechanism variables, showing more sensitivity to the water fluctuation variables as opposed to the radiative flux variables. All of the sites showed their lowest Ω value in 2012, the year of the severe drought in the Central US. The 2012 results further indicate the dependence on the water fluctuation variables. This was especially true with the perennial Kernza crop, which displayed much higher soil moisture values. In this regard, we believe that the ability of perennial Kernza to resist water stress and retain higher soil moisture values is both a result of its deeper roots, in addition to its higher Ω value. Through the analysis of both the site comparison and the comparison of the differences in years, we conclude that the perennial Kernza crop (US-KLS) is more similar in its microclimate effects to the C4 (US-KON) and mixed C3/C4 (US-KFS) grassland sites as opposed to its annual counterpart (US-ARM). This has implications for the role of perennial agriculture for addressing agricultural resilience under changing climate conditions.

Grassland disturbance increases monarch butterfly oviposition and decreases arthropod predator abundance

Many species of conservation concern depend on disturbance to create or maintain suitable habitat. We evaluated effects of disturbance on the eastern migratory monarch butterfly (Danaus plexippus L.), which has declined markedly in recent decades, primarily attributed to the loss of milkweed host plants from annual crop fields in the US Midwest. Currently, remaining milkweeds in this region primarily occur in perennial grasslands, where disturbance is infrequent, predatory arthropods are abundant, and seasonal patterns of plant phenology differ from crop fields. In a two-year study in Michigan, USA, we applied three treatments to 23 patches of common milkweed (Asclepias syriaca L.); one-third of each patch was left undisturbed, while the remaining thirds were mowed in either mid-June or mid-July, respectively, and allowed to regenerate. We subsequently measured effects on monarch oviposition, predator abundance, survival of sentinel eggs and larvae, and tested how milkweed phenology and aphid colonization—both of which are reset by disturbance—structure predation risk for immature monarchs. Monarchs laid more eggs on regenerating versus undisturbed stems under both mowing regimes. Predators were strongly suppressed by mowing treatments, requiring 2–4 weeks to recolonize milkweed after disturbance, and were more abundant on flowering or aphid-infested stems. We found no significant differences in monarch egg/larval survival, although it tended to be higher in mowed plots. Overall, monarchs laid more eggs on regenerating stems where their offspring may also experience enemy-free space. Future work should focus on testing grassland disturbance as a management tool to improve productivity of existing monarch breeding habitat.

Earthworm species in various land use systems in the Campos Gerais region of Lapa, Paraná, Brazil.

The Campos Gerais region of Paraná are on an ancient plateau of sandstone origin and are covered with a diverse vegetation including mainly grasslands and various types of Atlantic Forest (particularly Araucaria forest). The region represents an important natural capital for biodiversity conservation as well as for agricultural and forestry production. However, little is known of the species richness and diversity of soil macroinvertebrates in this region. In the present study we evaluated earthworm species occurrence and richness in five land use systems (LUS) in the southern part of the Campos Gerais in Lapa county. Earthworms were handsorted from up to 18 soil monoliths on five occasions over three years (Feb. 2014, Feb., Mar., Nov. 2015, Jul. 2016) in the following LUS: old native forest, native grassland, young regenerating forest and grass lawn in the Uru Reserve and annual crop fields (soybean) in neighboring private farms (not all systems were sampled on all occasions). Nine earthworm species belonging to four families and five genera were found, of which six were native and three exotic species (Dichogaster gracilis, Amynthas gracilis, A. corticis). Of the native species, Urobenus brasiliensis and Andiorrhinus duseni (a large bodied-worm) are already well known from S and SE Brazil, while the remaining four were new species that require further description (Fimoscolex n.sp.1 and n.sp.2, Glossoscolex n.sp.1 and n.sp.2). In general, more species were found in February (summer) than March and November. The cropping system (soybean) had the lowest abundance and species richness in relation to other sites, although in the young and old forests no earthworms were found on some sample dates. Given the several new species found in this small reserve, and the relatively few sites studied thus far in the Campos Gerais, further efforts are needed to adequately characterize the earthworm fauna of the region, from which many other species are expected.

PENGARUH PENANAMAN SENGON (Paraserianthes falcataria) TERHADAP KANDUNGAN C DAN N TANAH DI DESA RESAPOMBO, DOKO, BLITAR

Landuse change are suspected to be one responsible to soil fertility decline on Resapombo, Doko, Blitar. Efforts done by local farmers to deal with these problems are plantation of P. falcataria trough a reforestation program around 2011-2012. The benefits of the program are still need to be assessed so that this research was done (1) to compare the soil quality between P. falcataria-planted field and no P.falcataria field by the parameters of soil organic matter content and available N, (2) to study the relationship between organic matter input and soil organic matter content and available N, and (3) to identify factors affecting N availability post-P. falcatariaplantation. This research used randomized block design with 5 treatments (annual crop field, 3 and 6 years P. falcaria plantation field, agroforestry field with P. falcataria + coffee + talas plantation, and ex-P. falcataria-planted field. Soil were sampled compositely by 3 replication from 0-20 cm depth. Litter were sampled from a 0.5m2 sub-plot of each treatment. Results showed that P. falcataria plantations enhance soil fertility indicated by increased soil organic matter input to 10.6 times (monoculture) and 17.6 times (agroforestry) control, increased soil organic matter content by 1.5 times (monoculture) and 2.3 times(agroforestry) control, increased total N of 1.6 times (monoculture) and 2.4 times (agroforestry) control, increased ammonium by 1.7 times (monoculture) and 3.2 times (agroforestry) control, and increased nitrate by 2.4 times (monoculture) and 3.9 times(agroforestry) control.The increased soil N content of P. falcataria-planted field were caused by higher soil organic inputs compared to those with no P. falcataria plantation. Nitrogen availability affected by soil texture but have no relationship with soil pH. However, agroforestry fields showed higher pH, organic C, total N, and available N than monoculture P. falcataria fields. Measured soil chemical properties showed no significant change by the increase of P. falcataria age, moreover, they declined down towards control on ex-P. falcatariaplantation. This indicates that reforestation would only give a temporary soil quality enhancement.

PENGARUH PENANAMAN SENGON (Paraserianthes falcataria) TERHADAP KANDUNGAN C DAN N TANAH DI DESA RESAPOMBO, DOKO, BLITAR

Landuse change are suspected to be one responsible to soil fertility decline on Resapombo, Doko, Blitar. Efforts done by local farmers to deal with these problems are plantation of P. falcataria trough a reforestation program around 2011-2012. The benefits of the program are still need to be assessed so that this research was done (1) to compare the soil quality between P. falcataria-planted field and no P.falcataria field by the parameters of soil organic matter content and available N, (2) to study the relationship between organic matter input and soil organic matter content and available N, and (3) to identify factors affecting N availability post-P. falcatariaplantation. This research used randomized block design with 5 treatments (annual crop field, 3 and 6 years P. falcaria plantation field, agroforestry field with P. falcataria + coffee + talas plantation, and ex-P. falcataria-planted field. Soil were sampled compositely by 3 replication from 0-20 cm depth. Litter were sampled from a 0.5m2 sub-plot of each treatment. Results showed that P. falcataria plantations enhance soil fertility indicated by increased soil organic matter input to 10.6 times (monoculture) and 17.6 times (agroforestry) control, increased soil organic matter content by 1.5 times (monoculture) and 2.3 times(agroforestry) control, increased total N of 1.6 times (monoculture) and 2.4 times (agroforestry) control, increased ammonium by 1.7 times (monoculture) and 3.2 times (agroforestry) control, and increased nitrate by 2.4 times (monoculture) and 3.9 times(agroforestry) control.The increased soil N content of P. falcataria-planted field were caused by higher soil organic inputs compared to those with no P. falcataria plantation. Nitrogen availability affected by soil texture but have no relationship with soil pH. However, agroforestry fields showed higher pH, organic C, total N, and available N than monoculture P. falcataria fields. Measured soil chemical properties showed no significant change by the increase of P. falcataria age, moreover, they declined down towards control on ex-P. falcatariaplantation. This indicates that reforestation would only give a temporary soil quality enhancement.

Aggregating fields of annual crops to form larger-scale monocultures can suppress dispersal-limited herbivores

An important part of landscape ecology is determining how the arrangement (aggregation or fragmentation) of patches in space influences the population dynamics of foraging organisms. One hypothesis in agricultural ecology is that fine-grain spatial heterogeneity in cropping (many small agricultural fields) should provide better pest control than coarse-grain heterogeneity (few large agricultural fields); this hypothesis has been proposed as an explanation for the increased pest abundance associated with agricultural intensification. However, empirical studies have found mixed support for this hypothesis, and some, surprisingly, demonstrate a strong decrease in pest abundance with increased crop aggregation. We developed a spatially explicit simulation model of pest movement across an agricultural landscape to uncover basic processes that could reduce pest abundance in landscapes with fewer, larger fields. This model focuses on herbivore movement and does not include predation effects or other biological interactions. We found that field aggregation in the model led to severely reduced pest densities and further discovered that this relationship was due to an increased distance between fields and a decreased “target area” in more aggregated landscapes. The features that create a negative relationship between aggregation and pest densities rely on crop rotation and limited dispersal capabilities of the pests. These findings help to explain seemingly counter-intuitive empirical studies and provide an expectation for when field aggregation may reduce pest populations in agro-ecosystems.

Comparative Assessment of Soil Organic Carbon Stock Potential under Agroforestry Practices and Other Land Uses in Lowlands of Bale

Soil organic carbon is the carbon associated with soil organic matter that is made up of decomposed plant and animal materials. This study was conducted in Dallo Mena district to estimate the amount of soil carbon stock stored in shade grown coffee (SC) and homegarden agroforestry practices (HG), and adjacent natural forest (NF) and annual crop field (CF) and to show the potential of agroforestry practices in soil organic carbon storage capacity. The study site was selected based on spatial analogue approach. From each land uses nine plots were selected by using systematic sampling method following the transect line. Soil organic carbon stock (100cm depth) were the highest for the NF(170.11 ± 14.59 Mg ha-1), followed by SC(127.96 ± 9.43 Mg ha-1), HG(107.62 ± 12.55 Mg ha-1) and CF(97.56 ± 6.85 Mg ha-1). Agroforestry and other land uses of Dallo Mena districts are providing various ecological as well as economical benefits for the community. It is used as income source, conserving different plant species diversity and at the same time storing large amounts of soil organic carbon. Therefore, there is significant difference among natural forest, shade grown coffee agroforestry practice, homegarden agroforestry practice and annual crop field in soil organic carbon storage capacity.International Journal of EnvironmentVolume-6, Issue-3, Jun-Aug 2017, page: 1-14