Search

Copyright of Journal of Northwest A & F University - Natural Science Edition is the property of Editorial Department of Journal of Northwest A&F University (Natural Science Edition) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The economic viability of orchard sanitation practices, is crucial for sustainable apple production. However, our knowledge in this area is limited, particularly after the fruit is stored in the high-energy-consuming ultra-low oxygen (ULO) storage system. The objective of this 3-year study was to investigate the cost-benefit ratios of five sanitation treatments (lime sulfur-Lime-S, leaf collection-Collect-L, mulching-Mulch-C, lime sulfur + leaf collection, leaf collection + mulching) in integrated and organic apple orchards, considering the sale of apples after 6-month ULO storage. Cost-benefit analyses determined cost, total revenue, revenue for class 1 fruit (fruits without scab infection) and income surplus. Costs of ULO storage were twice higher in the integrated orchard (mean 3,064 EUR ha−1) than in the organic one (mean 1,512 EUR ha−1). Direct costs of the two combined sanitation treatments were significantly higher than the Lime-S and Collect-L treatments across all years and orchard systems. Analysis of variance for total revenue, revenue for class 1 fruit and income surplus revealed significant differences among years, sanitation treatments, and orchard systems. The total revenue and revenue for class 1 fruit were significantly higher in the integrated orchard (10,787 and 10,557 EUR ha−1, respectively) than in the organic one (8,713 and 7,742 EUR ha−1, respectively). The lowest total revenue and revenue for class 1 fruit were obtained in the non-sanitized control, while highest were recorded in the Collect-L or Collect-L + Mulch-C treatments. Collect-L and Collect-L + Mulch-C treatments provided the highest income surplus in all years and orchard systems. Kernel density estimations and frequency distributions indicated the widest variability for total revenue and revenue for class 1 fruit in the integrated orchard system. Correlation and linear regression analyses revealed significant relationship between total revenue and revenue for class 1 fruit in both orchard systems. In conclusion, our study demonstrates that Collect-L and Collect-L + Mulch-C treatments offer the greatest economic benefit after 6-month ULO storage regardless of the orchard system employed.

Societal Impact statement Reduced fungicide use lowers environmental pollution and enables safer food production. The usage of fungicides in apple orchards can be reduced through the application of sanitation practices which decrease the inoculum sources of apple scab disease on fallen leaves. This study found two non‐chemical sanitation practices, namely the collection of fallen leaves (CFL) and CFL combined with straw mulch in tree rows, were beneficial. These two practices are not only biologically and environmentally valuable, as they reduce disease levels and can replace chemical fungicides, but they are also economically efficient options for integrated and organic orchards compared to non‐sanitized ones. Summary Severe fungicide use can be reduced by applications of sanitation practices in order to reduce scab incidence, yield and fruit quality losses in apple orchards. In a 5‐year study, we aimed to investigate the effect of sanitation practices on biological and cost–benefit parameters in two sustainable apple management systems, and to find significant correlations among the parameters. We investigated the effect of five sanitation treatments (lime sulphur, leaf collection, mulching, lime sulphur + leaf collection, leaf collection + mulching) on four biological (scab incidence, fruit parameters: total yield, yield class I and II) and seven cost–benefit (three cost types, three annual revenue types, income surplus/deficit) parameters in integrated and organic apple orchards. Correlation, linear regression and principal component analyses (PCA) were performed to find correlations among biological and cost–benefit parameters. Results showed that fruit scab incidence was 3.4–8.1 times higher, while total yield was 1.4–1.8 times lower in the organic management system than in the integrated one. The treatment of leaf collection and/or leaf collection + mulching showed higher total cost (180.3 and 675.2 EUR ha−1) but lower scab incidence (5.3 and 27.3%; 4.8 and 26.7%, integrated and organic, respectively) and higher yield with greater total revenues (10,235 and 10,329 EUR ha−1; 8,136 and 8,230 EUR ha−1, integrated and organic, respectively) and income surpluses (851 and 451 EUR ha−1; 897 and 496 EUR ha−1, integrated and organic, respectively) compared to non‐sanitized control treatments in most cases. Other sanitation treatments provided fewer biological and/or no financial benefits. Results from correlation and linear regression analyses indicated strong relationships among the factors of total yield vs surplus, class I vs surplus, and fruit scab vs class II) in both management systems. Further relationships were detected among almost all parameters in the PCA. Overall, our study demonstrated that two non‐chemical sanitation treatments could not only reduce scab incidence and increase fruit yield, but could show positive cost–benefit outcomes in both management systems.

Societal Impact statement: Reduced fungicide use lowers environmental pollution and enables safer food production. The usage of fungicides in apple orchards can be reduced through the application of sanitation practices which decrease the inoculum sources of apple scab disease on fallen leaves. This study found two non‐chemical sanitation practices, namely the collection of fallen leaves (CFL) and CFL combined with straw mulch in tree rows, were beneficial. These two practices are not only biologically and environmentally valuable, as they reduce disease levels and can replace chemical fungicides, but they are also economically efficient options for integrated and organic orchards compared to non‐sanitized ones. Summary: Severe fungicide use can be reduced by applications of sanitation practices in order to reduce scab incidence, yield and fruit quality losses in apple orchards. In a 5‐year study, we aimed to investigate the effect of sanitation practices on biological and cost–benefit parameters in two sustainable apple management systems, and to find significant correlations among the parameters.We investigated the effect of five sanitation treatments (lime sulphur, leaf collection, mulching, lime sulphur + leaf collection, leaf collection + mulching) on four biological (scab incidence, fruit parameters: total yield, yield class I and II) and seven cost–benefit (three cost types, three annual revenue types, income surplus/deficit) parameters in integrated and organic apple orchards. Correlation, linear regression and principal component analyses (PCA) were performed to find correlations among biological and cost–benefit parameters.Results showed that fruit scab incidence was 3.4–8.1 times higher, while total yield was 1.4–1.8 times lower in the organic management system than in the integrated one. The treatment of leaf collection and/or leaf collection + mulching showed higher total cost (180.3 and 675.2 EUR ha−1) but lower scab incidence (5.3 and 27.3%; 4.8 and 26.7%, integrated and organic, respectively) and higher yield with greater total revenues (10,235 and 10,329 EUR ha−1; 8,136 and 8,230 EUR ha−1, integrated and organic, respectively) and income surpluses (851 and 451 EUR ha−1; 897 and 496 EUR ha−1, integrated and organic, respectively) compared to non‐sanitized control treatments in most cases. Other sanitation treatments provided fewer biological and/or no financial benefits. Results from correlation and linear regression analyses indicated strong relationships among the factors of total yield vs surplus, class I vs surplus, and fruit scab vs class II) in both management systems. Further relationships were detected among almost all parameters in the PCA.Overall, our study demonstrated that two non‐chemical sanitation treatments could not only reduce scab incidence and increase fruit yield, but could show positive cost–benefit outcomes in both management systems. [ABSTRACT FROM AUTHOR]

The economic viability of orchard sanitation practices, is crucial for sustainable apple production. However, our knowledge in this area is limited, particularly after the fruit is stored in the high-energy-consuming ultra-low oxygen (ULO) storage system. The objective of this 3-year study was to investigate the cost-benefit ratios of five sanitation treatments (lime sulfur-Lime-S, leaf collection-Collect-L, mulching-Mulch-C, lime sulfur + leaf collection, leaf collection + mulching) in integrated and organic apple orchards, considering the sale of apples after 6-month ULO storage. Cost-benefit analyses determined cost, total revenue, revenue for class 1 fruit (fruits without scab infection) and income surplus. Costs of ULO storage were twice higher in the integrated orchard (mean 3,064 EUR ha−1) than in the organic one (mean 1,512 EUR ha−1). Direct costs of the two combined sanitation treatments were significantly higher than the Lime-S and Collect-L treatments across all years and orchard systems. Analysis of variance for total revenue, revenue for class 1 fruit and income surplus revealed significant differences among years, sanitation treatments, and orchard systems. The total revenue and revenue for class 1 fruit were significantly higher in the integrated orchard (10,787 and 10,557 EUR ha−1, respectively) than in the organic one (8,713 and 7,742 EUR ha−1, respectively). The lowest total revenue and revenue for class 1 fruit were obtained in the non-sanitized control, while highest were recorded in the Collect-L or Collect-L + Mulch-C treatments. Collect-L and Collect-L + Mulch-C treatments provided the highest income surplus in all years and orchard systems. Kernel density estimations and frequency distributions indicated the widest variability for total revenue and revenue for class 1 fruit in the integrated orchard system. Correlation and linear regression analyses revealed significant relationship between total revenue and revenue for class 1 fruit in both orchard systems. In conclusion, our study demonstrates that Collect-L and Collect-L + Mulch-C treatments offer the greatest economic benefit after 6-month ULO storage regardless of the orchard system employed. [ABSTRACT FROM AUTHOR]

Conservation Agriculture (CA) and the System of Rice Intensification (SRI) are both agroecologically-oriented production systems that support more productive, sustainable, and resource-conserving farming, with synergies arising from their respective assemblages of reinforcing agronomic methods. This review article examines the compatibility between CA and SRI, considering examples of their being utilized in complementary ways. The application of CA principles enhances the growth, yield, and performance of the crops grown under the cropping system as well as the health and resilience of the whole ecosystem. SRI practices create more favorable conditions for the development of crop plants below- and above-ground, including conditions that can be enhanced by CA management. SRI practices such as reduced plant density m−2 can elicit a better phenotypic expression of the genetic potentials of crops grown with CA. For these two agronomic systems to converge at the field level, some of their respective practices for plant, soil, water, and nutrient management need to be modified or aligned. One such adaptation is to practice SRI in CA systems on permanent, no-till, mulch-covered raised beds, with rainfall or irrigation water in the furrows between the beds furnishing and controlling water and providing weed suppression and improved nutrient recycling. SRI rice cropping can benefit from the CA practices of no-tillage, mulch soil cover, and diversified cropping, both in paddies and on raised beds. Several examples have shown that this convergence of cropping systems is feasible for smallholding farmers as well as for larger-scale producers and also that SRI practices within a CA system are amenable to considerable mechanization. Further research and experimentation are needed to identify and assess appropriate practices for capitalizing upon their synergies. [ABSTRACT FROM AUTHOR]

Olive pruning residues are a by-product that can be applied to soil or used for energy production in a circular economy model. Its benefits depend on the amount of pruning, which varies greatly within farms. This study aimed to investigate the spatial variability of shreddable olive pruning in a traditional olive grove in Córdoba (Spain) with an area of 15 ha and trees distanced 12.5 m from each other. To model the spatial variability of shreddable olive pruning, geostatistical methods of stochastic simulation were applied to three correlated variables measured on sampled trees: the crown projected area (n = 928 trees), the crown volume (n = 167) and the amount of shreddable pruning (n = 59). Pearson's correlation between pairs of variables varied from 0.71 to 0.76. The amount of pruning showed great variability, ranging from 7.6 to 76 kg tree−1, with a mean value of 37 kg tree−1. Using exponential and spherical variogram models, the spatial continuity of the variables under study was established. Shreddable dry pruning weight values showed spatial autocorrelation up to 180 m. The spatial uncertainty of the estimation was obtained using sequential simulation algorithms. Stochastic simulation algorithms provided 150 possible images of the amount of shreddable pruning on the farm, using tree projected area and crown volume as secondary information. The interquartile range and 90% prediction interval were used as indicators of the uncertainty around the mean value. Uncertainty validation was performed using accuracy plots and the associated G-statistic. Results indicate with high confidence (i.e., low uncertainty) that shreddable dry pruning weight in the mid-western area of the farm will be much lower than the rest of the farm. In the same way, results show with high confidence that dry pruning weight will be much higher in a small area in the middle east of the farm. The values of the G-statistic ranged between 0.89 and 0.90 in the tests performed. The joint use of crown volume and projected areas is valuable in estimating the spatial variability of the amount of pruning. The study shows that the use of prediction intervals enables the evaluation of farm areas and informed management decisions with a low level of risk. The methodology proposed in this work can be extrapolated to other 3D crops without requiring modifications. On a larger scale, it can be useful for predicting optimal locations for biomass plants, areas with high potential as carbon sinks or areas requiring special soil protection measures. [ABSTRACT FROM AUTHOR]

The results of this study provide overall information on the verification of the effect of applying two different mulching materials of an organic origin to the soil surface in the area between rows of grape vines in vineyards on selected physical and chemical properties of the soil and, at the same time, on the yield and quality parameters of the grape vines (Vitis vinifera L.). During the period under study, 2018–2020, the effect of shredded cereal straw (CS) and compost from garden waste (CO) was investigated. The control variant (CWC) was left without any cover and was regularly cultivated with a coulter cultivator to a depth of 60 mm. During the experiments, meteorological data were monitored and recorded along with soil temperature and soil moisture for each variant. The results show that the lowest temperature was measured for the straw cover variant (11.10–11.87 °C), while the highest soil temperature was measured for compost (11.93–13.16 °C). Under the straw, the moisture level in the soil was higher compared to the other variants, and there was a gradual increase (of 3%) in soil bulk density values compared to the baseline. By contrast, the compost variant showed a decrease (of 1%) in bulk density values. The differences in nutrient content were slight among the variants. The only statistically significant difference was identified for the compost variant with respect to the content of total nitrogen and phosphorus. Further results demonstrated a positive effect of both mulch material variants on grape yield, which was 6–19% higher in the variants with a cover layer. In addition, the use of mulch also had a positive effect on grape quality. For example, the sugar content—one of the main quality parameters—increased by 1–7% due to the mulch layer. Based on these results, the use of mulching materials can be recommended for areas with low total rainfall during the growing season, as well as when growing varieties with irregular yields and uneven grape quality. [ABSTRACT FROM AUTHOR]

Abstract Cutslopes are the most important source of sediment among other parts of forest roads network. A significant amount of runoff and sediment is observed in Hyrcanian forests because of the fine-textured soil. This study investigated the effectiveness of three treatments of jute cover (JC), mulch cover (MC) and bare cutslope as control plots (CP) under the natural rainfall condition. Two months investigation on two new and old roads with silty-clay cutslopes was done. Correlation between some of soil properties, soil loss and runoff showed that the sediment concentration was increased with increasing in soil bulk density. Runoff volume showed a significant negative correlation with the percentage of organic matter and a positive correlation with the plastic limit. With runoff volume increasing, sediment concentration and soil loss were significantly increased. Analysis of the results showed that in both new and old roads, the treatment of JC is superior. This treatment has reduced soil loss by 9.68 times compared to CP treatment. The treatment of JC compared to the MC on a new cutslope and an old one has reduced soil loss by 2.77 and 2.54 times. Also, JC have reduced soil loss by 2.67 times compared to the MC. The total cost per square meter of JC is US $ 0.21 and this amount is equivalent to $ 0.26 for the MC. According to the results, it is suggested that soil protection and bioengineering designs should be focused on the use of JC. Highlights • How we can protect the soil in roads lateral? • Using the jut cover in soil stabilization • Soil stabilization treatments • Preventing of soil erosion in forest roads [ABSTRACT FROM AUTHOR]

Mulching the surface of soil after machinery traffic can offset some of the adverse effect of compaction of the soil caused by the machine. Thus, this study reported the response of cowpea (vigna-unguiculata) to compaction and mulching with elephant grass (Pennisectum purpuereum) on loamy sand soil in Southern Nigeria. A randomized split-block design of field plots with compaction levels as the main block and the mulching levels as the sub-block was used. The compaction treatment consisted of 0, 5, 10 and 15 passes of a tractor with a 31 kPa contact pressure while the mulching treatment consisted of 0%, 30%, 60% and 90% areal ground cover. The zero percent treatment served as control and each treatment was replicated twice. The soil dry bulk density, penetration resistance, soil moisture content and crop growth and yield parameters were measured. Results showed that compaction level significantly increased the dry bulk density, penetration resistance and reduced soil moisture content, crop growth and yield parameters; while mulching significantly increased soil moisture content, dry bulk density and reduced penetration resistance (P<0.05). The growth and yield parameter increased for 30% mulch cover and thereafter reduced for 60% and 90% mulch cover. Both the crop dry matter and grain yield had significant correlation (R² = 0.93 and 0.96, respectively) with mulch cover and compaction using surface response analysis. Multiple regressions showed that a ground cover of 40% will be optimum for cowpea production on uncompacted soil while up to 65% and 92% will be needed to complement the 5 and 10 passes of tractor to produce comparative yields respectively. [ABSTRACT FROM AUTHOR]

The assessment of soil organic carbon (SOC) content using proximal diffuse reflectance spectroscopy in the visible and near-infrared (Vis-NIRS) may be hampered if green plants (photosynthetic vegetation) and straw (non-photosynthetic vegetation) are present in the measuring spot. Under such conditions, taking spectra of the soil surface yields insufficient results and requires quantitative correction. In this combined lab and field study, we investigated if, and to what degree, it is possible to distinguish green plants and straw from bulk soil organic matter using the same Vis-NIR spectra. Without any modification of an approved SOC model, SOC was overestimated by more than 200%, depending on the fractional coverage with green leaves and straw. This error was more severe for green leaves than for straw. After covering the soil surface with defined proportions of green barley leaves or straw concomitant changes in reflectance spectra were recorded. Partial least squares regression (PLSR) with three factors yielded quantitative predictions of soil coverage by green leaves (R 2 adj = 0.98, RMSE cv of cross-validation = 5.3% soil coverage) and straw (R 2 adj = 0.95, RMSE cv = 7.5% soil coverage). Furthermore, photosynthetic and non-photosynthetic vegetation indices, the Normalized Difference Vegetation Index (NDVI) and the Cellulose Absorption Index (CAI), were derived from the Vis-NIR spectra of the soil surface. Both indices increased when covering with green leaves or straw increased (R 2 = 0.99 [NDVI] and 0.94 [CAI], respectively). The degree of SOC overestimation was correlated with NDVI and CAI. Second-order polynomial regressions between SOC overestimation, and CAI or NDVI were fitted (R 2 = 0.97 and 0.99, respectively). This enabled us to carry out a correction step after predicting SOC using an approved SOC model (R 2 adj = 0.84, RPD = 2.53, RMSE CV = 0.73) to minimize the overestimation error. Transferring this two-step-approach to field conditions revealed that Vis-NIR spectra still showed scattered predictions of point-specific SOC contents (R 2 = 0.66 and 0.58 for stop-and-go and on-the-go acquisitions, respectively), however, with a slope close to unity. Consequently, the disturbance by green plants or straw on the soil surface during superficial Vis-NIR sensing of SOC in the field can be overcome. [ABSTRACT FROM AUTHOR]

Reclaiming peatland ecosystems is challenging our understanding of how to rebuild functioning landscapes. Assisted succession may provide a practical approach to guide the reestablishment of peatlands in denuded landscapes. In Alberta, the majority of peatlands began as fens during the paludification process. This research focuses on creating fen initiation conditions to establish fen moss species on mineral sediment as an approach for peatland reclamation in the oil sands region., In a field mesocosm experiment, we evaluated the establishment of five common fen mosses ( Drepanocladus aduncus, Ptychostomum (Bryum) pseudotriquetrum, Campylium stellatum, Tomentypnum nitens and Aulacomnium palustre) introduced in equal proportions to clay loam. To determine the optimal hydrologic conditions for the establishment of each species, we tested four water levels (0, −10, −20 and −30 cm). We created vegetation types similar to those identified at the peat-mineral interface in peat profiles to determine the effect of herbaceous plant, low shrub and wood-strand mulch cover treatments on moss establishment., Three seasons after introduction, total moss cover averaged 40% and was greatest under all cover treatments and at the 0 cm water level. Total moss biomass averaged 95·5 g m−2 in moss introduction mesocosms and was greatest under low shrubs and herbaceous plants and at the 0 and −30 cm water levels. Fen moss species distribution was significantly influenced by water-table depth. Drepanocladus aduncus and Ptychostomum pseudotriquetrum were most common at 0 cm and Aulacomnium palustre and Tomentypnum nitens at −30 cm., In this approach, we created vegetation types similar to those found on mineral sediments at the base of Alberta peat cores and successfully established distinct fen moss communities along a water-table gradient and under shade cover. Introducing a suite of fen moss species that inhabit a range of hydrologic niches under low shrubs or herbaceous plants improves moss establishment., Synthesis and applications. Our research shows that it is possible to create fen initiation conditions on clay loam sediment by introducing foundation moss and vascular plant species at optimal water levels. Restoring the community structure and biomass accumulation that occurs in the initial stages of fen development appears to be a suitable target for peatland reclamation. These methods introduce a practical strategy to reclaim peatlands in the heavily impacted oil sands region of Alberta. [ABSTRACT FROM AUTHOR]

Apesar de efêmera, a rugosidade superficial no solo induzida por métodos de seu preparo é requerimento importante nos sistemas de manejo de caráter conservacionista. Isto se deve ao fato de que ela aumenta a retenção e a infiltração superficiais de água no solo, reduz a velocidade e o volume do escoamento superficial e aprisiona os sedimentos da erosão, diminuindo os danos causados pela erosão hídrica. Considerando tais aspectos, realizou-se esta pesquisa com o objetivo de avaliar as alterações ocorridas na rugosidade superficial do solo pelas ações do preparo e da chuva, na ausência e na presença de cobertura morta, em relação à erosão hídrica. O estudo foi realizado em campo, na EEA/UFRGS, em Eldorado do Sul (RS), em 1996 e 1997, aplicando-se chuva simulada sobre um Argissolo Vermelho distrófico típico, de textura franco-argilo-arenosa e declividade de 0,07 m m-1. Avaliaram-se os preparos de solo aração, aração e duas gradagens e sem preparo, na ausência e na presença de 60 % de cobertura por resíduo cultural, submetidos a quatro testes de chuva simulada. O primeiro teste foi constituído de uma chuva segmentada, composta de quatro porções, com durações de 20, 20, 30 e 30 min, espaçadas uma da outra de 30 a 40 min, aplicada logo após o preparo do solo. Os demais testes foram constituídos de chuvas contínuas, com duração de 90 min, aplicadas 1, 20 e 35 dias após a primeira chuva. Tais chuvas foram aplicadas com o aparelho simulador de chuva de braços rotativos, na intensidade constante de 64,0 mm h-1. A alteração na rugosidade superficial do solo causada pelo preparo foi maior do que a causada pela chuva. O maior decréscimo na rugosidade superficial do solo pela ação da chuva ocorreu já no primeiro evento, logo após o solo ter sido preparado, antes do início da enxurrada. A rugosidade superficial do solo impediu ou retardou a enxurrada nos tratamentos com solo mobilizado nos segmentos de chuva de curta duração, aplicados logo após o preparo, impedindo ou reduzindo as perdas de água e solo naquele período, independentemente da cobertura do solo. Nas chuvas contínuas subseqüentes, de longa duração, a rugosidade superficial do solo não influenciou a perda de água nos tratamentos com solo mobilizado na ausência de cobertura, sendo alta em todos eles, mas a influenciou na sua presença, diminuindo-a com o aumento da rugosidade. O tratamento sem preparo permaneceu com a perda de água elevada sempre em tais chuvas. Quanto à perda de solo, nas mesmas chuvas, o efeito da rugosidade na sua redução foi mais evidente na ausência de cobertura, tendo sido substancialmente ocultado na sua presença. A cobertura morta adicionada ao solo não preservou a elevada rugosidade superficial inicialmente criada pelos preparos no solo degradado utilizado no estudo. Mesmo assim, ao final do experimento, ainda restava mais da metade da capacidade teórica inicial de retenção de água e de sedimento nas microdepressões formadas pela rugosidade. Os dados obtidos foram consistentes com teorias e conceitos usados em estudos de mecânica de erosão hídrica do solo.Although being temporary, the presence of tillage-induced surface roughness in the soil is an important requirement in conservation tillage systems. The reason is that surface roughness increases both surface retention and surface infiltration of water in the soil, reduces runoff velocity and volume, and traps eroded sediments, thus reducing water erosion damages. With this in mind, this study was developed with the objective of evaluating modifications in soil surface roughness by tillage and rainfall actions related to water erosion, in the absence and presence of mulch cover. The experiment was carried out in the field, at the Agriculture Experimental Station of the Federal University of Rio Grande do Sul (EEA/UFRGS), in Eldorado do Sul County, Rio Grande do Sul State, Brazil, in 1996 and 1997, using simulated rainfalls on a sandy clay loam Paleudult with 0.07 m m-1 slope steepness. The tillage types evaluated in the study included plowing, plowing plus double-disking and no-till, all them in the absence and presence of 60% soil cover (oat residue), submitted to four simulated rainfall tests. The first test consisted of a rainfall segmented in four portions, lasting for 20, 20, 30, and 30 min, separated 30 to 40 min from each other, applied immediately after tillage. The remaining tests consisted of uninterrupted rains of 90-min duration, applied 1, 20, and 35 days after the first rain. These rainfalls were applied with the rotating-boom rainfall simulator at a constant intensity of 64.0 mm h-1. Tillage caused greater changes in the soil surface roughness than rainfall. Soil surface roughness was most reduced by rain action in the very first event in recently- tilled soil, in the pre-runoff period. Soil surface roughness impeded or delayed runoff in treatments with soil mobilization in the rainfall segments with short duration applied soon after tillage, impeding or reducing water and soil losses in that period, regardless of soil cover. In the continuous, subsequent long rains, surface roughness did not influence water loss in the studied treatments without cover, where it was high throughout the experimental period, but it did reduced water loss in the presence of cover. Water loss in no-till was high for such rains throughout the experiment. Under the same rain type, soil loss reduction as influenced by roughness was more evident in the absence of cover, whereas it was substantially obscured in its presence. Mulch of crop residue added to the soil surface did not preserve the initially high surface roughness created by tillage in the degraded soil used in the study. Nevertheless, by the end of the experiment more than half of the theoretical initial water and sediment retention capacity still remained in the microdepressions formed by roughness. The obtained data were consistent with theories and concepts used in soil erosion mechanics studies.

A three-year study was conducted to determine the effect of urea and lime sulphur sanitation treatments on three saprophytic development stages of Blumeriella jaapii on two sour cherry cultivars in integrated and organic orchards. The sanitation treatments in the integrated orchard included sprays of urea applied in the autumn, sprays of urea followed by mulch cover, and non-sanitized control. Urea was replaced with lime sulphur in the treatments in the organic orchard. The percent survival of three saprophytic development stages of B. jaapii (i.e., saprophytic hyphal growth, mycelial aggregates, and presence of apothecia and/or winter acervuli) ranged between 11 and 70 % and between 21 and 67 % in the urea and lime sulphur treatments, in the integrated and organic orchards, respectively. In all years, all urea and lime sulphur treatments significantly ( P < 0.05) reduced the percent survival of the three development stages of B. jaapii compared to non-sanitized plots in both orchards and on both cultivars. Treatments that included a mulch cover resulted in a generally lower percent survival of the three development stages of B. jaapii than treatments that did not include the mulch cover, but their significance varied among the B. jaapii development stages, for years, cultivars and orchards. An interpretation of the importance of these sanitation treatments for orchard management practices is discussed. [ABSTRACT FROM AUTHOR]

Abstract: Experimental research revealed that mulching the soil surface is an effective soil conservation practice. However, reported effectiveness of mulch covers varies widely and there are indications that spatial measurement scale (i.e. plot length) explains part of this variability. The objective of this study is therefore to analyse the impacts of plot length at which field and laboratory experiments were conducted on the effectiveness of mulch covers in reducing soil loss by water erosion. In this review, 41 studies investigating the impacts of mulch cover on soil erosion by water are analysed (plot length ranges between 0.1 and 30.5 m). Calculated mulch effectiveness factors, i.e. b-values from the mulch factor equation, range between 0.0097 and 0.1320 and increase linearly with plot length for the reviewed experiments: b =0.022+0.0017⁎plot_length (m); R 2 =0.37; n =41. However, care should be taken when using this relationship for extrapolations to longer plots. Furthermore, slope gradient, soil type and mulch type determine the variability of the effectiveness of mulch covers in reducing soil erosion rates by water. Depending on the dominant soil erosion process (i.e. splash, interrill, rill and interrill or rill erosion), these variables also partly control the effectiveness of a mulch cover in reducing soil erosion by water. [Copyright &y& Elsevier]