Tillage force prediction from terrain characterization with the bevameter

The relationship between the soil parameters measured during soil testing using the bevameter system and horizontal forces acting on a simple tillage tool were investigated. Field experiments were conducted on untilled, compacted and recently tilled soil. On both soils, five sites were randomly chosen where bevameter and draft measurements were performed. The parameters measured were modulus of soil deformation, wet and dry bulk density, soil moisture content, tool operating depth, tool operating speed and horizontal draft.

A statistical analysis of data indicated that a mathematical model for predicting draft should include operating depth, dry bulk density and modulus of deformation.     

Long-term tillage and wheel traffic effects on a poorly drained mollic ochraqualf in northwest Ohio. 1. Soil physical properties, root distribution and grain yield of corn and soybean

Effects of 12 years of 4 tillage systems, were studied on soil bulk density, infiltration rate, penetration resistance, structural stability of aggregates, root length density, moisture release characteristics and grain yield. The objective of this study was to assess long-term effects of tillage methods and guided traffic on soil properties and crop response on a heavy-textured poorly drained soil. Tillage systems included: (A) continuous no-till for 12 years; (B) no-till for 10 years followed by plow-till for 2 years; (C) plow-till for 10 years followed by no-till for 2 years; (D) continuous plow-till for 12 years. Wheel tracks had significant effects on soil physical properties. Soil in the traffic zone (TZ) in no-till treatment had higher bulk density and penetration resistance (PR) for the upper 0–30-cm layer than plow-till treatment. The PR for the surface layer in TZ was 25–46% more than in the row zone (RZ). Mean soil bulk density in the TZ of no-till plots was about 12% more than in the RZ (1.53 vs. 1.36 g cm⁻³). Changeover from no-till to plow-till decreased PR in RZ and TZ by 50–60% while that from plow-till to no-till increased PR by 10–20%. Similar effects were observed in percent aggregation and the mean weight diameter. In no-till treatments both initial and equilibrium infiltration rates were significantly lower in TZ than RZ (27.5 vs. 6.8 cm h⁻¹ initial and 10.0 vs. 1.5 cm h⁻¹ final). There were more macropores (> 2 mm) for the TZ in no-till compared with the plow-till treatments. Fine or micropores were comparatively more numerous in the sub-soil of no-till than plow-till treatments. The median aggregate size (D₅₀) was 6.2, 4.2, 4.8 and 3.5 mm for Treatments A, B, C and D, respectively. Root length density of corn in plow-till plots was significantly more than that in no-till plots for the top 0–20-cm layer. Corn and soybean yields were greater in plow-till than no-till treatments. Grain yields in Treatment D were greater than those in Treatment A by 10% for corn and by 6% for soybean.     

Landscaping and performance of some aesthetic plant species in hot, arid conditions of India

Establishment of ornamental and aesthetic plants in hot, arid conditions of India is difficult due to the prevailing climatic, edaphic and biotic factors. Effect of turfgrass on the growth of ornamental plants in hot arid conditions has not been studied so far anywhere in the world. A study was conducted on the campus of Arid Forest Research Institute, Jodhpur, India to assess the performance of a few ornamental plant species in combination with turfgrass and without turfgrass with respect to different soil tilling intervals. Growth of plants was better with turfgrass than without turfgrass. We suggest adopting a soil tilling interval of 30 days to achieve optimum growth of ornamental plant species in terms of height and crown diameter. Our results can help reduce labor costs and achieving better landscapes in fewer days in hot urban conditions of Indian sub continent.     

Status and Regeneration of Himalayan Maple in the Himachal Pradesh: Honing Red List of Plants

The population status and regeneration of a data-deficient tree species were examined in both protected and unprotected areas. The target species was found in six habitat types, seven aspects between 2,100- to 3,300-m altitude, and sites dominated by different species. The species was best represented in a shady moist habitat, north and northwest aspects, altitudinal range >2,700 m, and sites dominated by Acer caesium in both protected and unprotected sites; but the generalized linear model indicated nonsignificant effect of sites, habitat, altitude, and dominance except for aspects. Difference in sapling and seedling density among aspects and sites only was significant. Probability of use and resource use index indicated poor preference and less pressure as fuel. It can be concluded that the species is not under any significant threat in the study area. But, further studies on population status, regeneration, and relationship with environmental factors in a wider geographic region are suggested to evaluate species and place under suitable priority category.     

Dissolution of Dominant Soil Phosphorus Fractions in Phosphorus-Responsive Soils of Bihar,India: Effects of Mycorrhiza and Fertilizer Levels

We investigated the effects of Arbuscular Mycorrhiza (AM) fungi and various phosphorus (P) levels on the distribution and availability of P in dominant soils of Bihar, India. Potassium chloride (KCl)-P (labile P), sodium hydroxide (NaOH)-P (Fe-Al-bound P), hydrochloric acid (HCl)-P (Ca-bound P), and residual P (Res-P) fractions were analyzed in the soils under maize plant. Ca-bound P was the most abundant P fraction in the alkaline soils (65% of the total P) followed by neutral soil (35% of the total P), whereas it was less abundant (<4%) in the acidic soil type. Fe-Al-bound P was found to be highest for acidic soil (65% of the total P). Soils under the inoculation with Glomus mossae and control gave the highest and lowest values (15.63 mg kg^?1 and 10.74 mg kg^?1 respectively) for the labile fraction which was similar to the organically bound residual fractions of P (200.17 mg kg^?1 and 193.66 mg kg^?1 respectively. Inoculation of the soils with AM fungi leads to the redistribution of P fractions in different soils which consequently helps in improvement of available P in soil conducive for plant uptake.     

红豆和白扁豆种子萌发和生长对盐胁迫的响应及其生理机制

为探讨红豆和白扁豆种子萌发及幼苗生长对盐胁迫的响应及其生理机制,以红豆品种‘渝红豆2号’和传统白扁豆品种为材料,分别用不同浓度NaCl （0 mmol·L^-1、20 mmol·L^-1、40 mmol·L^-1、60 mmol·L^-1、80 mmol·L^-1、100 mmol·L^-1）溶液处理种子,测定不同NaCl浓度胁迫下红豆和白扁豆种子的发芽指标及幼苗生长指标、叶片丙二醛（MDA）含量、超氧化物歧化酶（SOD）和过氧化物酶（POD）活性,分析NaCl胁迫对红豆和白扁豆种子萌发及幼苗生长的影响。结果表明：1）随NaCl浓度增加,红豆和白扁豆种子发芽率、发芽势、发芽指数和活力指数均呈下降趋势。当NaCl浓度为80 mmol·L^-1时,白扁豆发芽势、发芽指数、活力指数降为0,红豆的发芽势、发芽指数、活力指数分别为20.00%、2.00、0.83;NaCl浓度为100 mmol·L^-1时,红豆的发芽率为16.67%,但白扁豆为0,这表明在盐胁迫下红豆较白扁豆具有更高的萌发能力。2）红豆与白扁豆相对盐害率随NaCl浓度的增加而增加,当NaCl浓度为80 mmol·L^-1和100 mmol·L^-1时,白扁豆相对盐害率为96.58%和96.67%,红豆相对盐害率为47.05%和83.18%,说明红豆受盐害程度较低。3）红豆与白扁豆幼苗胚根、胚芽及鲜重均随NaCl浓度增加而下降。NaCl浓度为100 mmol·L^-1时,白扁豆胚根长为0,红豆胚根长为0.23 cm。4）随NaCl浓度升高,红豆和白扁豆叶片的MDA含量均增加,造成细胞膜透性逐渐增大,但是红豆幼苗MDA积累量低于白扁豆,这表明红豆叶片细胞膜损伤较小。5） NaCl胁迫下,红豆与白扁豆SOD活性均显著升高,但红豆SOD活性显著高于白扁豆;NaCl胁迫下,POD活性显著升高,但白扁豆POD活性显著下降。研究发现红豆可通过提高SOD和POD活性以降低细胞膜氧化伤害,减少MDA积累量,进而提高种子萌发能力。在相同浓度NaCl胁迫下红豆较白扁豆有更高的耐盐性,能更好地适应盐胁迫环境。     

Spatial variability of total soil carbon and nitrogen stocks for some reclaimed minesoils of southeastern Ohio

Reclamation of drastically disturbed minesoils and subsequent planting of trees and/or grasses can result in a rapid build‐up of carbon (C) in the soil. However, the amount of C sequestered in reclaimed minesoils may vary with the amount of time since reclamation. In this study, we assessed total carbon (TC) and total nitrogen (TN) concentrations for reclaimed minesoils located in northeastern Ohio and characterized by distinct reclamation age chronosequences. Reclaimed minesoils studied were R78G, reclaimed in 1978 and immediately seeded to grass; R82GT, reclaimed in 1982 and immediately seeded to grass and trees were planted 5 years later; and R87G, reclaimed in 1987 and immediately seeded to grass. An unmined site, UMG, was also included as a reference. Our objectives were to evaluate the variability with respect to mean and the spatial variability of pH, bulk density (ρ_b), TC and TN concentrations, and stocks in each reclaimed minesoil. Thirty soil samples were collected at each of the 0–15, 15–30, and 30–50 cm depth. The coefficient of variation (CV) for ρ_b was least, <15 per cent at each site and depth. For TN concentration and stock, CV was moderate, 15–35 per cent, in each field except the UMG where it was high, >35 per cent at 0–15, and 15–30 cm depths. For TC concentration and stocks, CV was high, >35 per cent, across all minesoils and generally increased with depth. The C/N ratio followed the same tend as TC and TN stocks and ranged from 40 per cent to 123 per cent across minesoils. Geostatistical analysis also showed an increase in sample variance with increasing amount of time since reclamation for most soil properties under investigation. Sample variance for TC concentration and stocks also increased with depth in reclaimed minesoils. However, no definite relationship emerged between amount of time since reclamation and the spatial dependence of TC and TN concentrations and stocks. Overall this study showed that reclamation of drastically disturbed minesoils increased the soil C concentration and stocks and reclamation by initially seeding to grasses followed by planting trees was the best management option for speedy accretion of soil C and soil quality enhancement. Copyright © 2007 John Wiley & Sons, Ltd.     

Carbon stocks in Ethiopian soils in relation to land use and soil management

The effect of soil management and land use change are of interest to the sustainable land management for improving the environment and advancing food security in developing countries. Both anthropogenic changes and natural processes affect agriculture primarily by altering soil quality. This paper reviews and synthesizes the available literatures related to the influence of soil management and land use changes on soil carbon (C) stock in Ethiopia. The review shows that topsoil C stock declines approximately 0–63%, 0–23%, and 17–83% upon land use conversion from forest to crop land, to open grazing, and to plantation, respectively. An increase of 1–3% in soil C stock was observed within 10 years of converting open grazed land to protected enclosures. However, there was a little change in soil C stock below 20 cm depth. There is a large potential of increasing SOC pool with adoption of land restorative measures. Total potential of soil C sequestration with the adoption of restoration measures ranges 0·066–2·2 Tg C y⁻¹ on rain‐fed cropland and 4·2–10·5 Tg C y⁻¹ on rangeland. Given large area and diverse ecological conditions in Ethiopia, research data available in published literature are rather scanty. Therefore, researchable priorities identified in this review are important. Copyright © 2008 John Wiley & Sons, Ltd.     

Soil and nutrients losses under different crop covers in vertisols of Central India

Purpose

Accelerated erosion removes fertile top soil along with nutrients through runoff and sediments, eventually affecting crop productivity and land degradation. However, scanty information is available on soil and nutrient losses under different crop covers in a vertisol of Central India. Thus, a field experiment was conducted for 4 years (2010–2013) to study the effect of different crop cover combinations on soil and nutrient losses through runoff in a vertisol.

Materials and methods

Very limited information is available on runoff, soil, and nutrient losses under different vegetative covers in a rainfed vertisol. Thus, the hypothesis of the study was to evaluate if different crop cover combinations would have greater impact on reducing soil and nutrient losses compared to control plots in a vertisol.

This experiment consisted of seven treatment combinations of crop covers namely soybean (Glycine max) (CC₁), maize (Zea mays) (CC₂), pigeon pea (Cajanus cajan) (CC₃), soybean (Glycine max)?+?maize (Zea mays) ??1:1 (CC₄), soybean (Glycine ma x))?+?pigeon pea (Cajanus cajan) ?2:1 (CC₅), maize (Zea mays)?+?pigeon pea (Cajanus cajan) ??1:1 (CC₆), and cultivated fallow (CC₇). The plot size was 10?×?5 m with 1% slope, and runoff and soil loss were measured using multi-slot devisor. All treatments were arranged in a randomized block design with three replications.

Results and discussion

Results demonstrated that the runoff and soil loss were significantly (p?<?0.05) higher (289 mm and 3.92 Mg ha^?1) under cultivated fallow than those in cropped plots. Among various crop covers, sole pigeon pea (CC₃) recorded significantly higher runoff and soil loss (257 mm and 3.16 Mg ha^?1) followed by that under sole maize (CC₂) (235 mm and 2.85 Mg ha^?1) and the intercrops were in the order of maize?+?pigeon pea (211 mm and 2.47 Mg ha^?1) followed by soybean?+?maize (202 mm and 2.38 Mg ha^?1), and soybean?+?pigeon pea (195 mm and 2.15 Mg ha^?1). The lowest runoff and soil loss were recorded under soybean sole crop (194 mm and 2.27 Mg ha^?1). The data on nutrient losses indicated that the highest losses of soil organic carbon (SOC) (25.83 kg ha^?1), total nitrogen (N), phosphorus (P), and potassium (K) (7.76, 0.96, 32.5 kg ha^?1) were recorded in cultivated fallow (CC₇) as compared to those from sole and intercrop treatments. However, sole soybean and its intercrops recorded the minimum losses of SOC and total N, P, and K, whereas the maximum losses of nutrients were recorded under pigeon pea (CC₃). The system productivity in terms of soybean grain equivalent yield (SGEY) was higher (p?<?0.05) from maize?+?pigeon pea (3358 kg ha^?1) followed by that for soybean?+?pigeon pea (2191 kg ha^?1) as compared to sole soybean. Therefore, maize?+?pigeon pea (1:1) intercropping is the promising option in reducing runoff, soil-nutrient losses, and enhancing crop productivity in the hot sub-humid eco-region.

Conclusions

Study results highlight the need for maintenance of suitable vegetative cover as of great significance to diffusing the erosive energy of heavy rains and also safe guarding the soil resource from degradation by water erosion in vertisols.