The recovery of soil properties and the proper growth of natural tree regeneration are key elements for maintaining forest productivity after selective logging operations. This study was conducted on the soil properties and natural growth of two pioneer seedling species of alder and maple which were on skid trails in the mixed beech forests of northern Iran. To examine the long-term effects, we randomly selected six skid trails, with two replicates established for each of three time periods since last use (10, 20, and 30 years ago). Random plots 4 m × 10 m in size, three plots on each skid trail and six plots on areas without soil compaction (control), were selected. Measurements included the physical and chemical properties of the soil and the growth, and the architectural and qualitative characteristics of the seedlings. The results showed that all the soil properties of the 10- and 20-year-old skid trails were significantly different from the control area (except for the soil moisture in the 20-year-old skid trail). The 30-year-old skid trail showed values of other soil properties which were not significantly different from the control area, except for the amounts of organic matter and soil nitrogen, which was less than the control. The skid trails had a negative effect on all of the growth, qualitative, and architectural indices of seedlings. The characteristics of seedlings were related to soil characteristics and had the highest correlation with the soil penetration resistance (R-value from -0.41 to -0.63 for stem growth, p < 0.05; -0.57 to -0.90 for root growth, p < 0.01; and -0.76 to -0.86 for biomass, p < 0.01). The correlation coefficient between soil penetration resistance and the Dickson quality index of alder and maple seedlings was, respectively, -0.74 and -0.72, p < 0.01. The negative effect of soil compaction on root growth (-27.69% for alder seedlings and -28.08% for maple seedlings) was greater than on stem growth (-24.11% for alder seedlings and -16.27% for maple seedlings). The amount of growth, qualitative, and architectural indices of alder seedlings were higher than that of maple seedlings. Although alder is a better choice as compared to maple seedling in the initial year, the results of our study show that it is recommended to plant both alder and maple on skid trails after logging operations.

Rice fallow black gram is grown under the residual moisture situation as a relay crop in heavy texture montmorillonite clay soil under zero till condition. Since the crop is raised during post monsoon season, the crop often experiences terminal stress due to limited water availability and no rainfall. Surface irrigation in montmorillonite clay soil is determent to pulse crop as inundation causes wilting. Therefore, zero tilled rice fallow black gram has to be supplemented with micro irrigation at flowering stage (35 days after sowing) to alleviate moisture stress and to increase the productivity as well. Hence micro farm pond in a corner of one ha field was created to harvest the rain water during monsoon season and the same was utilized to supplement the crop with lifesaving irrigation through mobile sprinkler at flowering stage for the crop grown under conservation agriculture. Soil cracking is also the common phenomena of montmorillonite clay soil where evaporations losses would be more through crack surfaces. The present study was therefore conducted to study the changes in the soil physical properties, crop establishment and productivity in conjunction with mechanized sowing and harvest and supplemental mobile sprinkler irrigation. Sowing of black gram by broadcasting 10 days prior to the manual harvest of rice, manual drawn single row seed drill after the machine harvest of rice and sowing by broadcasting at 4 days prior to machine harvest of rice was experimented separately and in combination with lifesaving irrigation. Results indicated that the number of wheel passes and lifesaving irrigation had a very strong impact on soil penetration resistance and soil moisture. Combined harvester followed by no till seed drill increased the soil penetration resistance in all the layers (0-5 cm, 5-10 cm and 10-15 cm). Two passes of wheel increased the mean soil penetration resistance from 407 KPa to 502 KPa. The soil penetration resistance (0-5 cm) at harvest shown that black gram sown by manual broadcasting 10 days prior to manual harvest of paddy supplemented with life irrigation on 30 DAS reduced the soil penetration resistance from 690 Kpa to 500 Kpa, 740 Kpa to 600 Kpa and 760 Kpa to 620 Kpa respectively at 0-5 cm, 5-10 cm and 10-15 cm layer. In general, moisture depletion rate was rapid in the surface layer of 0-5 cm as compared to other layers of 5-10 cm and 10-15 cm up to 30 DAS (Flowering stage). The moisture content and the soil penetration resistance had an inverse relationship. The soil penetration resistance also had an inverse relationship with the root length in which the root length lowers as the soil penetration resistance increases. The soil crack measured at 60 DAS was deeper with no till seed drill (width of 3.94 cm and depth of 13.67 cm) which was mainly due to surface layer compaction. The relative water content, specific leaf weight and chlorophyll content were significantly improved through the supplemental irrigation given on 30 DAS irrespective of crop establishment methods. The results further indicated that compaction of ploughed layer in the moist soil due to combined harvester and no till seed drill had a negative impact on yield (457 kg ha-1), which was improved by 19.03 per cent due to increased soil moisture with supplemental irrigation. The mean yield increase across different treatments due to supplemental lifesaving irrigation through mobile sprinkler was 20.4 per cent.

The planting effect and the planting potential of 12 cover crops (Leguminous: alfalfa, smooth vetch, hairy vetch, red clover, white clover, common vetch; non-leguminous: sudangrass, green radish, Nitro radish, rape, kale, endive) in the Sanjiang Plain of Northeast China were comprehensively evaluated by soil penetration resistance, pre-winter biomass, root characteristics, and plant nitrogen accumulation. The results showed that all the 12 cover crops grew normally during the experimental sowing period. Compared with the control, all the cover crops successfully reduced soil compactness. The planting of green radish, nitro radish, and sudangrass decreased soil penetration resistance by 47.1%, 43.4% and 33.4%, respectively. The pre-winter total fresh biomass of cover crop populations was between 3.38 and 13.98 kg·m-2, and the total dry matter mass was between 0.78 and 2.43 kg·m-2. The biomass of non-leguminous cover crops was significantly higher than that of the leguminous cover crops. The group roots of radish, rape and endive had large volumes. In particular, the nitro radish roots had a vo-lume of 4018.5 cm3·m-2, and the root system of sudangrass extended over the widest horizontal range. The ash content of leguminous cover crops was significantly lower than that of non-leguminous species, which could provide more organic matter with high decomposability. The total nitrogen accumulation of cover crops varied from 18.72 to 53.09 g·m-2. Kale and endive accumulated the highest amount of nitrogen and large biomass, which could facilitate nitrogen fixation and accumulation. According to the type of main crops in Sanjiang Plain and canopy structure, planting leguminous (clover, vetch, and alfalfa) and non-leguminous (radish, kale and sudangrass) cover crops to plant inter-row or in a line mixed cropping pattern could regulate soil structure and promote nutrient cycing, with positive effects on the fertility of black soil in the Sanjiang Plain.
以土壤紧实度、冬前生物量、根系性状、植株氮累积量等为指标对供试12种覆盖作物(豆科:紫花苜蓿、光叶苕子、毛叶苕子、红三叶、白三叶、箭筈豌豆;非豆科:苏丹草、青萝卜、Nitro radish、甘蓝型油菜、羽衣甘蓝、菊苣)在东北三江平原地区的种植效果及应用潜力进行综合评价。结果表明: 12种覆盖作物在试验播期均能正常生长,不同覆盖作物与对照相比均有利于降低土壤紧实度,其中青萝卜、Nitro radish和苏丹草土壤紧实度下降最显著,分别较对照下降了47.1%、43.4%和33.4%;覆盖作物群体冬前鲜生物量为3.38～13.98 kg·m-2,干生物量为0.78～2.43 kg·m-2,非豆科覆盖作物的生物量显著高于豆科覆盖作物;覆盖作物的群体根系体积以萝卜、油菜、菊苣较大,尤其Nitro radish的根体积高达4018.5 cm3·m-2,苏丹草的根系横向延展范围最宽;豆科覆盖作物的灰分含量显著低于非豆科覆盖作物,能提供更多易分解的有机物质;覆盖作物总氮积累量为18.72～53.09 g·m-2,其中,羽衣甘蓝和菊苣的氮积累量最高,且生物量相对较大,有利于氮的积累和固定。在三江平原地区根据主栽作物的类型与冠层结构,选择豆科的三叶草、苕子、紫花苜蓿和非豆科的萝卜、羽衣甘蓝、苏丹草作为覆盖作物进行行间或行内混播的种植方式,可以在调控土壤结构的同时促进养分循环,有利于三江平原黑土地力的提升。.

Soil seed banks play a central role in vegetation dynamics and may be an important source of ecological restoration. However, the vast majority of seed bank studies examined only the uppermost soil layers (0-10 cm); hence, our knowledge on the depth distribution of seed bank and the ecological significance of deeply buried seeds is limited. The aim of our study was to examine the fine-scale vertical distribution of soil seed bank to a depth of 80 cm, which is one of the largest studied depth gradients so far. Our model systems were alkaline grasslands in East-Hungary, characterised by harsh environmental conditions, due to Solonetz soil reference group with Vertic horizon. We asked the following questions: (1) How do the seedling density and species richness of soil seed bank change along a vertical gradient and to what depth can germinable seeds be detected? (2) What is the relationship between the depth distribution of the germinable seeds and the species traits?
In each of the five study sites, four soil cores (4 cm diameter) of 80 cm depth were collected with an auger for soil seed bank analysis. Each sample was divided into sixteen 5-cm segments by depth (320 segments in total). Samples were concentrated by washing over sieves and then germinated in an unheated greenhouse. Soil penetration resistance was measured in situ next to each core location (0-80 cm depth, 1-cm resolution). We tested the number and species richness of seedlings observed in the soil segments (N = 320), using negative binomial generalized linear regression models, in which sampling layer and penetration resistance were the predictor variables. We ran the models for morphological groups (graminoids/forbs), ecological groups (grassland species/weeds) and life-form categories (short-lived/perennial). We also tested whether seed shape index, seed mass, water requirement or salt tolerance of the species influence the vertical distribution of their seed bank.
Germinable seed density and species richness in the seed bank decreased with increasing soil depth and penetration resistance. However, we detected nine germinable seeds of six species even in the deepest soil layer. Forbs, grassland species and short-lived species occurred in large abundance in deep layers, from where graminoids, weeds and perennial species were missing. Round-shaped seeds were more abundant in deeper soil layers compared to elongated ones, but seed mass and ecological indicator values did not influence the vertical seed bank distribution. Our research draws attention to the potential ecological importance of the deeply buried seeds that may be a source of recovery after severe disturbance. As Vertisols cover 335 million hectares worldwide, these findings can be relevant for many regions and ecosystems globally. We highlight the need for similar studies in other soil and habitat types to test whether the presence of deep buried seeds is specific to soils with Vertic characteristics.

Water is the most limiting resource for global crop production. The projected increase of dry spells due to climate change will further increase the problem of water limited crop yields. Besides low water abundance and availability, water limitations also occur due to restricted water accessibility. Soil penetration resistance, which is largely influenced by soil moisture, is the major soil property regulating root elongation and water accessibility. Until now the interactions between soil penetration resistance, root system properties, water uptake and crop productivity are rarely investigated. In the current study we quantified how interactive effects between soil penetration resistance, root architecture and water uptake affect water accessibility and crop productivity in the field. Maize was grown on compacted and uncompacted soil that was either tilled or remained untilled after compaction, which resulted in four treatments with different topsoil penetration resistance. Higher topsoil penetration resistance caused root systems to be shallower. This resulted in increased water uptake from the topsoil and hence topsoil drying, which further increased the penetration resistance in the uppermost soil layer. As a consequence of this feedback, root growth into deeper soil layers, where water would have been available, was reduced and plant growth decreased. Our results demonstrate that soil penetration resistance, root architecture and water uptake are closely interrelated and thereby determine the potential of plants to access soil water pools. Hence, these interactions and their feedbacks on water accessibility and crop productivity have to be accounted for when developing strategies to alleviate water limitations in cropping systems.