Decrease Soil Erosion Research Articles

The effect of tillage intensity and time of herbicide application on weed communities and populations in maize in central Europe

Soil-conserving cropping systems aim at reducing tillage intensity to decrease soil erosion, leaching of nitrate and pesticides, and production costs. They are, therefore, likely to change the efficiency of weed control and hence weed populations. There is a lack of information on how reduced tillage systems, especially no-tillage (NT), affect the development of weed populations and the efficiency of weed control of maize crops under the humid, temperate climate of large parts of Europe. An experiment was conducted at two sites of the Swiss midlands to investigate the impact of the time of chemical weed control on weed populations in different tillage systems. Pre- and post-emergence herbicides were applied in a conventional tillage (CT) system with a moldboard plough, in a minimum tillage (MT) system with a chisel plough, and in a NT system in a winter wheat ( Triticum aestivum L.)–oilseed rape ( Brassica napus L.)–winter wheat–maize ( Zea mays L.) crop rotation. Crop residues were left on the field and stubble tillage was not carried out. The density of weeds in treatments without herbicide tended to be lower in NT than in MT and CT. An analysis of variance and canonical discriminant analysis (CDA) showed that perennial weeds such as Epilobium spp. L. and Sonchus arvensis L. were related to NT, and annual broad-leaved species were associated with MT and CT. In general, post-emergence weed control was more efficient than pre-emergence weed control regardless of the tillage system. However, NT systems may be adopted successfully when weed control measures are adapted to changing weed populations.

Jackson receives international prize

A visionary plant scientist, Wes Jackson, is a recently announced recipient of the ‘Alternative Nobel Prize’ from the Swedish Parliament, awarded in December. Wes Jackson co-founded The Land Institute (Salina, KS, USA), which focuses on developing alternative cash-crop farming practices. The practices include developing perennial crop plants and growing multiple grains together, resulting in a farming system of ‘perennial polyculture.’ The approach mimics interactions found in native prairies. The advantages of this type of farming include ecological stability, decreased soil erosion, and reduced agrochemical pollution. Jackson says the farming method is still decades away from realization. For more information, contact The Land Institute (www.landinstitute.org) and The Right Livelihood Award (www.rightlivelihood.se). TS.

More people, more erosion? Land use, soil erosion and soil productivity in Murang'a district, Kenya

Intensification of land use can become a threat to agricultural sustainability if they lead to increased soil erosion. This study examines land-use changes, soil and water conservation, soil erosion and soil productivity in the Highlands of Kenya. In addition, it examines farmers' perception of livelihood changes. Land-use changes were determined from interpretations of aerial photographs taken in 1960 and 1996. Additional information on land use, soil and water conservation and livelihood changes were obtained from discussions and interviews with farmers, as well as from field verifications of the most recent aerial photographs. Soil samples were analysed and soil erosion assessed according to the PLUS classification scheme. The results indicate that substantial changes in land use, such as introduction of coffee and high-yielding maize, and fragmentation of land holdings have taken place. Less land was conserved in 1996 as compared to 1960. Moreover, SWC practices have changed from fanya chini terraces and shifting cultivation to bench terraces and permanent cultivation. Rates of soil nutrients (organic C, N and K) and maize-yield levels decreased significantly with increasing erosion. Farmers' perception of livelihood changes was differentiated according to farmers' off-farm resource 60 per cent of the farmers depended on income from the land and thought livelihoods were better in the 1960s. It is concluded that more efforts to decrease soil erosion and investments in land and labour are necessary to sustain soil productivity and hence secure rural livelihoods. Copyright © 2000 John Wiley & Sons, Ltd.

Addressing global warming and biodiversity through forest restoration and coastal wetlands creation

The Climate Challenge is a partnership between the Department of Energy and the electric utility industry to reduce, avoid, and sequester greenhouse gases. A portion of the initiative, the sequestration of greenhouse gases, is the focus of this presentation. Over 4 million acres of bottomland hardwood forests were cleared for agriculture in the Mississippi River Valley in the 1970s. Reestablishing these forests would improve depleted wildlife habitats, serve as wildlife corridors, increase biodiversity, and decrease soil erosion. Also, Louisiana is losing coastal wetlands at a rate of approximately 25 square miles/year. This coastal erosion is due to a number of factors and many efforts are currently underway to address the matter. One such effort is the use of material generated in the dredging of navigational canals; however, this material is low in nutrient value, making the regeneration of marsh grasses more difficult. In addition, bottomland hardwood forests and coastal wetland grasses are excellent ‘carbon sinks’ because they take carbon dioxide out of the atmosphere and store it in living plant tissue. Entergy Services, Inc. is an electric utility with a service territory that comprises portions of both the Lower Mississippi River Valley and the Gulf of Mexico coastline. This provides an opportunity to positively address both habitat losses noted above while at the same time addressing global warming, forest fragmentation, and biodiversity. Entergy, through its affiliation with the UtiliTree Carbon Company, is participating in projects that will investigate the feasibility of using bottomland hardwood reforestation on cleared marginal farmlands now managed by the Louisiana Department of Wildlife and Fisheries and the US Fish and Wildlife Service. Entergy has also begun a research project with the Environmental Protection Agency and the State of Louisiana. The research is a compost demonstration project that will utilize wood waste generated through our tree-trimming program as a compost material that will be mixed with low nutrient dredge material to create new coastal wetlands. Taken together, Entergy’s initiatives will be able to address global warming through carbon sequestration, restore fragmented forest habitats, reduce coastal erosion and improve the quality of a vital coastal aquatic nursery habitat. Efforts will be made to manage the created habitats for biodiversity. Pulling all these ideas together creates an effect in which the whole is greater than the sum of the parts. In such a synergy of ideas, there are no losers and the winners are both industry participants and the environment.

Decreased rates of alluvial sediment storage in the coon creek basin, wisconsin, 1975-93

The total measured rate of alluvial sediment accretion in the agricultural Coon Creek Basin for the period 1975-93 was only about 6 percent of the rate that occurred in the 1930s, but the distributed changes within the basin were highly variable and systematic. Sediment yield (efflux), however, remained relatively constant despite large stream and valley changes within the basin. These observations demonstrate (i) that sediment sources, sinks, and fluxes vary widely over time and space and (ii) that, although improved soil conservation measures have decreased soil erosion, the downstream effects are complex.

Rolled erosion control systems for hillslope surface protection: a critical review, synthesis and analysis of available data. II. The post-1990 period

The application of rolled erosion control systems (RECSs) to disturbed hillslopes has significantly increased during the 1990s. Erosion-related research conducted on RECSs during the post-1990 period was dominated by black-box output studies with minimal attention to erosion process relationships. Additionally, many studies failed to incorporate suitable treatment replication, and in others influential variables were not controlled between experiments making results difficult to interpret. However, there were some important advances made in laboratory rainfall simulation studies, controlled greenhouse studies, and rainfall simulation studies. The first detailed studies attempting to link material properties of RECSs and their erosion control effectiveness were initiated; links between salient material properties of RECSs and erosion process dynamics (interrill and rill) were formally explored; detailed studies of the influence of RECSs on hydrological and microclimatological variables were examined in both greenhouse and field experiments; and an examination of temporal variations in runoff and erosion were introduced into the RECS literature. Despite recent advances there are still a number of significant gaps in our understanding. These gaps are exacerbated by lack of standard field or laboratory testing protocols. Two of the outstanding questions which need further study include: What are the most critical properties of RECSs that decrease soil erosion and runoff, but enhance growth of vegetation? What are the most effective organic or synthetic RECSs in controlling erosion on a variety of slopes and soil textures? It is argued that standardized protocols are needed, but these must include adequate replication and randomization. Additionally, there must be an emphasis on understanding the basic surface or near-surface processes influenced by RECSs (i.e. erosional, hydrological, biological, and climatological). © 1998 John Wiley & Sons, Ltd.

Rolled erosion control systems for hillslope surface protection: a critical review, synthesis and analysis of available data. I. Background and formative years

Landscapes disturbed by human activities commonly have erosion rates accelerated by several orders of magnitude over pre-disturbance conditions. New approaches to effectively decrease soil erosion rates from disturbed lands are urgently required to decrease non-point source pollution. One such best management practice (BMP) combines the application of rolled erosion control systems (RECSs), composed of either natural or synthetic fibers, with seeding of hillslopes to enhance biomass production. This synergistic approach is thought to be one of the most appropriate for mitigating excessive soil erosion on disturbed non-agricultural hillslopes. Over the past decade an active erosion control industry (ECI) has developed, and a variety of different RECSs have been brought to market. However, limited scientific data are available to the land manager, specifier, or design engineer to assess the relative effectiveness of these products in reducing sediment yield and in enhancing the development of vegetation. Few studies exist that have rigorously compared RECSs using a well-developed experimental design. Most studies lack sufficient replication and/or randomization. Additionally, in many studies there is a failure to control variables between cycles, runs, or events, including antecedent moisture content and sediment availability. The result is a mass of information that can be potentially misused to justify the selection of a given product that may be less effective than a competing product. The objectives of this two-part paper are: (i) to synthesize all available erosion-related literature dealing with RECSs applied to hillslopes during two periods: up to 1990 and post-1990; (ii) to highlight important scientific contributions to the literature on RECSs; (iii) to assess the scientific rigor of various studies, and re-analyze and re-interpret data when available; and (iv) to make constructive suggestions to improve future studies to develop a quantitative linkage between the physical characteristics of RECSs, soil erosion processes, and vegetation cover. © 1998 John Wiley & Sons, Ltd.

Rolled erosion control systems for hillslope surface protection: a critical review, synthesis and analysis of available data. I. Background and formative years

Landscapes disturbed by human activities commonly have erosion rates accelerated by several orders of magnitude over pre-disturbance conditions. New approaches to effectively decrease soil erosion rates from disturbed lands are urgently required to decrease non-point source pollution. One such best management practice (BMP) combines the application of rolled erosion control systems (RECSs), composed of either natural or synthetic fibers, with seeding of hillslopes to enhance biomass production. This synergistic approach is thought to be one of the most appropriate for mitigating excessive soil erosion on disturbed non-agricultural hillslopes. Over the past decade an active erosion control industry (ECI) has developed, and a variety of different RECSs have been brought to market. However, limited scientific data are available to the land manager, specifier, or design engineer to assess the relative effectiveness of these products in reducing sediment yield and in enhancing the development of vegetation. Few studies exist that have rigorously compared RECSs using a well-developed experimental design. Most studies lack sufficient replication and/or randomization. Additionally, in many studies there is a failure to control variables between cycles, runs, or events, including antecedent moisture content and sediment availability. The result is a mass of information that can be potentially misused to justify the selection of a given product that may be less effective than a competing product. The objectives of this two-part paper are: (i) to synthesize all available erosion-related literature dealing with RECSs applied to hillslopes during two periods: up to 1990 and post-1990; (ii) to highlight important scientific contributions to the literature on RECSs; (iii) to assess the scientific rigor of various studies, and re-analyze and re-interpret data when available; and (iv) to make constructive suggestions to improve future studies to develop a quantitative linkage between the physical characteristics of RECSs, soil erosion processes, and vegetation cover. © 1998 John Wiley & Sons, Ltd.

Ski slope vegetation at Snoqualmie Pass, Washington State, USA, and a comparison with ski slope vegetation in temperate coniferous forest zones

Ski slope vegetation at Snoqualmie Pass in Washington State, USA, was surveyed in order to identify community types and to compare it with vegetation development patterns in Japan. Ski slopes in Japan, most of which were constructed after 1960, underwent heavy land recontouring, while those at Snoqualmie Pass were constructed before 1950 with less modification. Three points apply to Japanese ski slope vegetation and differentiate these slopes from those at Snoqualmie Pass: (i) grasslands of introduced species are widespread and persistent; (ii) unvegetated patches are uncommon; and (iii) wetland vegetation has developed. These differences are mainly derived from the intensity of human impact, history of the slope and its scale: namely, ski slopes in Washington are older and larger than those in Japan. Ski slope vegetation in Washington was primarily differentiated by a soil moisture gradient. The large size of Washington ski slopes permitted the inclusion and development of wetland habitats, whereas most ski slopes in Japan are constructed on ridges and do not contain wetlands. Most introduced species in Japan are eliminated soon after seeding. In contrast, the long‐term management of ski slopes decreased soil erosion and/or unvegetated patches in Washington and created relatively permanent grasslands composed of introduced species. Tsuga heterophylla and Abies amabilis were found established on the ski slopes in Washington, whereas in Japan the pioneer tree species are shade‐intolerant broadleaved species. These differences may be a result of the different disturbance histories of ski slopes in the two countries. In addition, along with the conifers, early successional forbs such as Anaphalis margaritacea and Epilobium angustifolium are well established on Washington ski slopes. Results show that disturbances created by ski slope development greatly affect the vegetation, even on older, less heavily impacted ski slopes.

Ten reasons why organic growers do not use synthetically compounded fertilzers

Abstract Organic growers traditionally have placed synthetically compounded fertilizers onto the list of products which they ban. Generally, synthetically compounded fertilizers are very simple compounds that supply nutrients to plants. They are not even all inorganic if urea is classed as organic. Synthetically compounded fertilizers are identical with similar compounds found in nature. Plants cannot tell the difference. There are, however, at least ten compelling reasons for using natural organics as fertilizers: (a) Recycling for political and economic reasons, (b) Recycling to conserve natural resources, (c) To decrease soil acidification, (d) To decrease soil erosion and compaction by increasing levels of soil organic matter, (e) To protect groundwaters from nitrate buildup, (f) To protect surface waters from algal bloom, (g) To help have a favorable soil biology, (h) To help improve water‐use efficiency, (i) Some synthetically compounded fertilizers are dangerous to produce, and (j) “Organic” certif...

Corn Response to Rye Cover Crop Management and Spring Tillage Systems

AbstractThe use of a winter rye (Secale cereale L.) corn (Zea mays L.) doable cropping sequence in combination with appropriate tillage practices could increase biomass production and reduce soil erosion potential in southern Ontario. A 3‐yr study (1982–1984) was conducted at two locations to determine the potential of this sequence for double cropping, and to evaluate spring tillage systems and management of the rye residue on subsequent productivity of corn. Winter rye was planted in early October after corn silage harvest, and either chemically killed or harvested as silage in the spring before corn planting. Rye treatments consisted of no rye, rye harvested in the spring and rye residue left on the plots. Spring cultivation treatments were no‐till, tandem discing, and mold board plowing followed by secondary tillage. The use of a winter rye cover crop delayed corn development and reduced corn biomass yield by 11% at the Elora location and by 17% at the Woodstock location. The adverse effect of the rye crop was more pronounced under no‐till than where the soil was tilled. Removal or retention of the rye residue had no consistent effect on the subsequent corn crop. An allelopathic effect resulting from the rye crop may be one plausible explanation for the reduction in corn yield. Total biomass yield (rye + corn) was increased relative to corn alone, if the soil was cultivated. Therefore, a winter rye‐corn sequence may still be of interest, despite a reduction in corn yield, especially if advantages such as total biomass production and the potential for decreased soil erosion during fall and winter are considered.

Water‐Droplet Energy and Soil Amendments: Effect on Infiltration and Erosion

AbstractThe impact energy of water droplets from rain or overhead sprinklers can cause a seal to form at the soil surface. This constitutes a severe problem in agricultural lands in the arid and semiarid regions. Spreading a soil conditioner on the surface of the soil and providing a constant supply of electrolytes may prevent seal formation. The effect of droplet impact energy and water quality on infiltration and erosion was studied, using a tank drip‐type rain simulator, in a sandy loam soil (Typic Rhodoxeralf) treated with an anionic polyacrylamide (PAM) and phosphogypsum (PG). Three kinetic energies (KE) of 3‐mm diameter drops were obtained by varying their falling heights. The two qualities of water were distilled water (DW) and tap water (TW), to simulate rain and irrigation water, respectively. Increasing the impact energy reduced the infiltration rate (IR), cumulative infiltration (rain intake), and soil erosion in all treatments. Addition of PAM in the presence of electrolytes (either PG or TW) increased both final IR and cumulative infiltration by 7‐ to 8‐fold compared with the control, and was much more effective than PAM, PG, or TW alone. The PAM + electrolyte treatments decreased soil erosion by more than one order of magnitude compared with the control.

RUNOFF AND EROSION CONTROL IN POTATO FIELDS

In ridged and furrowed potato fields, we studied the beneficial effect fo phospho-gypsum (PG) and of the diked-furrows technique on runoff and erosion control. Spreading 10 t ha−1 of PG over the soil surface after seeding reduced runoff from the field 6-fold and reduced soil loss from the ridges to the bottom of the furrows 20-fold. In the diked-furrows treatment there was no runoff at all and ridge erosion was similar to that of the control. The effect of 5 and 25% slope and addition of PG on runoff and erosion from the same sandy soil (Typic Rhodexeralf) was studied in the laboratory using a rain simulator. When the slope was increased, soil loss increased 2-fold and 12-fold in the PG treatment and the control, respectively. PG was very beneficial in preventing soil erosion from the steep slope. The dissolution of PG by the rainwater and the ensuing release of electrolytes decreased soil erosion by: (1) increasing the fraction of rain that penetrated into the soil, (2) increasing the stability of the aggregates at the soil surface, and (3) enhancing the rate of entrained sediment deposition.

Municipal organic wastes and composts for arid areas

Abstract Municipal organic wastes offer many benefits for application to arid soils, including (1) increased soil fertility, (2) increased water retention in the soil, (3) decreased soil erosion, and (4) decreased fertilizer requirements. Both refuse and sewage sludge are sources of municipal organic wastes. This paper presents health and environmental considerations on the use of municipal organic wastes and waste processing requirements to prepare the materials for use.

Effect of N rate and tillage on yield, N accumulation and leaf N concentration of grain sorghum

Conservation tillage is an accepted method of decreasing soil erosion. However, limited information is available concerning N fertilizer requirements of grain sorghum ( Sorghum bicolor L. Moench) grown under reduced-tillage management. Tillage effects on sorghum yield and N accumulation in 1985 and 1986 were studied on a Weswood soil (Fluventic Ustochrept) near College Station, Texas (Latitude 30° 35′ N, Longitude 96° 21′ W). Four N rates (0, 50, 100 and 150 kg N ha −1) were applied to plots managed with no-tillage or conventional tillage. Response of grain yield to N rate was curvilinear while that of stover yield was linear. However, tillage and N interactions also influenced grain and stover yield. At low N rates, conventional tillage produced more stover and grain, but at higher rates tillage differences did not occur. Both tillage systems attained maximum grain yield at 122 kg N ha −1 as determined by regression analysis. Nitrogen accumulation in both stover and panicles was linear with N rate. Lower whole-plant N accumulation with no-tillage at low N rates supported the contention that N was less available in no-tillage soils. Leaf N concentration at anthesis was higher in conventional-tillage treatments. However, a regression of leaf N concentration on N rate predicted a maximum leaf N concentration of 34 g N kg −1 at 164 kg N ha −1 for both tillage treatments. When grain yield was regressed on leaf N concentration for each tillage treatment, maximum yield occurred at leaf N concentrations of 32 and 37 g kg −1 for conventional tillage and no-tillage, respectively. Leaf area index measured at anthesis significantly increased with N rate and was greater in conventional tillage. Leaf N concentration and leaf area index were positively correlated with grain yield. Data from this study suggest that fertilizer N amendments to no-tillage sorghum in excess of that required for maximum conventional-tillage yields are not necessary.

Relations between summer crops and ground cover legumes in a subtropical environment 2. Effects of sorghum and sunflower on the growth of Vigna trilobata and Medicago scutellata

Vigna trilobata (L.) Verdc. is a low growing legume with potential as a ground cover for controlling soil erosion in cropping lands of the subhumid/semi-arid subtropics of northern Australia. When it was grown beneath sorghum ( Sorghum bicolor (L.) Moench) and sunflower ( Helianthus annuus L.) crops under well-watered conditions on a vertisol in southern Queensland it decreased their yields by about 20% in the first season. This paper reports the effects of competition from crops sown at a normal dryland density or at half the normal density on its growth. V. trilobata sown in pure stand in October produced 531 g m −2 of above-ground dry matter, and sown in January produced 323 g m −2, by the time the grain crops sown at the same time were mature. Yields under mature sorghum sown at the normal density (10 plants m −2) in October and January were 38% and 35% respectively of those from pure stands of ground cover sown at the same time. Under sunflower at the normal density (5 plants m −2), corresponding values were 42% and 22%. The decrease in dry matter yield attributable to competition for water, nutrients and/or radiation from the main crops was proportional to the decrease in intercepted radiation. V. trilobata responded to shade in several ways, but a substantial increase in specific leaf area, together with some additional partitioning of dry matter to leaf, was sufficient to ensure that its leaf area index under crops was similar to that in pure stands. Seed yields of 116 and 84 g m −2 were obtained from pure stands of V. trilobata sown in October and January respectively. However, seed yields under crops sown at the normal density were only 4–18% of those measured in pure stands. Seed size was not affected by treatment. We conclude that, under well-watered conditions in southern Queensland, V. trilobata grown as a ground cover under crops of sorghum and sunflower should be able to produce sufficient biomass to decrease soil erosion, and also produce sufficient seed for regeneration in successive seasons. Its growth and suitability are also briefly compared with those of an alternative ground cover legume, Medicago scutellata (L.) Mill. (snail medic).

Relations between summer crops and ground cover legumes in a subtropical environment 1. Effects of a Vigna trilobata ground cover on growth and yield of sorghum and sunflower

An annual form of Vigna trilobata (L.) Verdc., a semi-domesticated herbaceous legume, was used to provide additional ground cover under rainfed crops in a subtropical environment. This study reports effects of V. trilobata on growth and yield of sorghum ( Sorghum bicolor (L.) Moench) and sunflower ( Helianthus annuus L.). Crops were sown on a vertisol in south-east Queensland in October and January at densities of 10 and 5 plants m −2 for sorghum and 5 and 2.5 plants m −2 for sunflower, and with or without ground cover legume. Crop rows were 0.8 m apart. V. trilobata seed was broadcast at 150 seeds m −2 when the crops were sown. While a full profile of soil water at sowing, and 330 to 424 mm rainfall during crop growth, led to vigorous growth of both crops and ground cover, crops from both sowings experienced water stress from about anthesis to the middle of grain fill. At the higher crop density, yields of sorghum grain were 453 and 355 g m −2 and yields of sunflower seed were 161 and 227 g m −2 after sowing in October and January, respectively. Yields were decreased to 87%, 70%, 76% and 90% respectively in the presence of up to 330 g m −2 of dry matter of V. trilobata. Sorghum yields were marginally lower at the lower density and decreased relatively more in the presence of ground cover. Neither the yield of sunflower seed, nor the effect of ground cover on it, was affected by density. Competition from ground cover decreased radiation interception by crops through decreasing their leaf area index. It did not appear to affect the efficiency of conversion of intercepted radiation to dry matter. Tiller number in sorghum was decreased by ground cover, except in the low density stand sown in October. Effects of ground cover on the contribution of tiller heads to yield were more severe, leading to a halving of their contribution at the lower density. Lower grain yields in the presence of ground cover were due to lower numbers of seeds m −2 in both crops. Seed size was also smaller in sunflower, but the percentage of oil was not affected. We conclude that under well-watered conditions in south-east Queensland the decreases in yields of summer crops in competition with V. trilobata are likely to be outweighed by the anticipated long-term benefits from using ground cover to decrease soil erosion. The need for information on the processes and consequences of competition under drier conditions is emphasized, so that we can evaluate the broader potential for ground cover legumes in the subhumid subtropics.

CONTROL OF SOIL EROSION BY POLYMERIC SOIL CONDITIONERS

Polyacrylamide polymers are useful in forming water-stable aggregates in soil. They not only have a favorable effect on water infiltration in soil, but also decrease the erodibility of soil. To stabilize soil, the polymers are either mixed dry with soil and then subjected to a wetting, drying, and cultivation cycle or solutions containing polymers are applied to cultivated soil. Five diferent situations where polymers can decrease soil erosion are described. The first situation involves application to soil several centimeters deep to improve water penetration, so that there is less water runoff and less erosion. The second situation involves application to the surface up to a 2-cm depth of soil to create water-stable aggregates that resist erosion. The third situation involves spraying polymers in solution or applying dry material followed by wetting onto the soil surface, so that after drying the stable structure of the surface of soil will not easily break during rain storms, even thought water will penetrate, but with much running off. The soil may not be cultivated in this situation. The fourth situation involves applying polymers to soil via irrigation water to decrease soil erosion by the irrigation water, particularly from furrows. The fifth situation involves applying polymers to driveways and playing fields to decrease erosion of dust by wind. Tested rates of the polymers that inhibited erosion were much lower than those rates used for the product Krilium over 30 years ago.

Influence of Surface Roughness and Clod Size and Stability on Soil and Water Losses

AbstractRough cloddy surfaces increased infiltration and decreased soil erosion compared to smoother surfaces as determined by simulated rainfall studies. Overtilling reduced surface roughness and cloddiness. One field experiment showed that a rough surface decreased runoff by 77% and soil erosion by 89% of that from a smooth surface. Tillage of wet soil increased surface roughness, but another field experiment showed that clods resulting from plowing the soil when wet were quite unstable compared with clods from plowing nearer the upper plastic limit. Tilling of compacted soil results in greater cloddiness than tilling of uncompacted soils. However, a laboratory experiment showed that compacted loam clods were less resistant to breakdown by water drop energy than those from uncompacted soil. Compaction of silty clay loam and silty clay soils did not change their stability significantly. To be effective as an erosion control measure, soil clods must be large enough and stable enough to keep infiltration at a high level until the crop canopy covers the soil surface. These studies describe the size and stability necessary to maintain a high level of runoff and erosion control.

The process of rehabilitation of mined forest lands toward degraded forest ecosystem recovery in Kalimantan, Indonesia

Sudarmadji T, Hartati W. 2016. The process of rehabilitation of mined forest lands toward degraded forest ecosystem recovery in Kalimantan, Indonesia. Biodiversitas 17: 185-191. An overview of mined forest lands at East and Central Kalimantan Indonesia was conducted to determine most important influencing factors supporting degraded forest ecosystem recovery. Consecutivestages of rehabilitation processes consist of reclamation-backfilling, re-contouring, re-shaping, topsoils spreading, and revegetationland preparation, planting, maintenance covering minimum topsoils spreading, soil acidity, plant hole size, soil improvement application (dolomite, organic-inorganic fertilizers), vegetation planting vegetation planting (plant species selection-quality and site matching-verified plantmaterial sources, hardening-off, planting techniques), and land management implementation. The potential degraded forest ecosystem recovery was shown by cover crops and fast growing species plant and undergrowths, survive primary species, decreasing surface runoff/overland flows following increasing soil infiltration capacities, decreasing soil erosion rate and it’s erosion hazard, and an improved environments as habitat for invading wildlifes. The general characteristics of potential degraded forest ecosystem recovery after rehabilitation processes are: spread soil materials thickness > 70 cm, bulk density + 1,2 g.ml-1, soil acidity > 5,5, macro nutrients (N, P, K, Ca, Mg)-low to moderate, decreasing overland water flow following increasing soil infiltration capacity-moderate to high, decreasing soil erosion rate-very low to moderate, decreasing erosion hazard level-very slight to moderate, growing plants of fast growing species with significant layers and land cover, and growing interline planted primary species. Viewed from the ecological aspect, in the revegetated degraded forest lands wildlife such as insects, birds, reptiles, amphibians and small mammals were found feeding and alsopermanently living in ecosystem regeneration following gradual habitat improvement. The ecosystem status was identified as a progression towards degraded forest ecosystem recovery.