Near-Surface Soil Chemical Properties as Affected by Cover Crops Over Time in the Lower Mississippi River Valley

Typical row-crop agricultural practices can potentially be harmful to soil health and future sustainability. The use of cover crops (CC) as a mechanism to improve soil health on a wide scale remains underutilized. Soil health remains a major concern for the sustainability of agricultural productivity, therefore, research into CC implementation as a mean to preserve or improve soil health is warranted. The objective of this study was to evaluate the effects of CC on the soils in the eastern Arkansas portion of the Lower Mississippi River Valley (LMRV) over time for various chemical soil parameters, including pH, soil organic matter (SOM), soil elemental contents (i.e., P, K, Ca, Mg, S, Na, Fe, Mn, Zn, Cu, and B), soil respiration, and a generalized soil health score index. Soil pH decreased over time under both CC and no-cover-crop (NCC) treatments, by −0.3 and −0.2, respectively. Soil OM decreased over time under NCC by −0.1%, but did not differ between CC treatments. Soil N availability decreased over time under NCC (−22.6 kg·ha−1), but did not change over time under CC. Soil respiration decreased over time under both CC and NCC, by −76.1 mg·L−1 and −77.3 mg·L−1, respectively, though there was no effect of CC treatment. The Haney soil health score index decreased under CC (−7.0) and NCC (−6.8) without an effect from CC treatment. Results of the study place emphasis on the temporal nature of soil health as influenced by cover crops and their potential to improve soil health.

Impact on Soil Organic C and Total Soil N from Cool- and Warm-Season Legumes Used in a Green Manure-Forage Cropping System

Annual forage legumes are important components of livestock production systems in East Texas and the southeastern US. Forage legumes contribute nitrogen (N) to cropping systems through biological N fixation, and their seasonal biomass production can be managed to complement forage grasses. Our research objectives were to evaluate both warm- and cool-season annual forage legumes as green manure for biomass, N content, ability to enhance soil organic carbon (SOC) and soil N, and impact on post season forage grass crops. Nine warm-season forage legumes (WSL) were spring planted and incorporated as green manure in the fall. Forage rye (Secale cereale L.) was planted following the incorporation of WSL treatments. Eight cool-season forage legumes (CSL) were fall planted in previously fallow plots and incorporated as green manure in late spring. Sorghum-sudangrass (Sorghum bicolor x Sorghum bicolor var. sudanense) was planted over all treatments in early summer after forage rye harvest and incorporation of CSL treatments. Sorghum-sudangrass was harvested in June, August and September, and treatments were evaluated for dry matter and N concentration. Soil cores were taken from each plot, split into depths of 0 to 15, 15 to 30 and 30 to 60 cm, and soil C and N were measured using combustion analysis. Nylon mesh bags containing plant samples were buried at 15 cm and used to evaluate decomposition rate of above ground legume biomass, including change in C and N concentrations. Mungbean (Vigna radiata L. [Wilczek]) had the highest shoot biomass yield (6.24 t DM ha-1) and contributed the most total N (167 kg∙ha-1) and total C (3043 kg∙ha-1) of the WSL tested. Decomposition rate of WSL biomass was rapid in the first 10 weeks and very slow afterward. Winter pea (Pisum sativum L. spp. sativum), arrow leaf clover (Trifolium vesiculosum Savi.), and crimson clover (Trifolium incarnatum L.) were the most productive CSL in this trial. Austrian winter pea produced 8.41 t DM ha-1 with a total N yield of 319 kg N ha-1 and total C production of 3835 kg C ha-1. The WSL treatments had only small effects on rye forage yield and N concentration, possibly due to mineralization of N from a large SOC pool already in place. The CSL treatments also had only minimal effects on sorghum-sudangrass forage production. Winter pea, arrow leaf and crimson clover were productive cool season legumes and could be useful as green manure crops. Mungbean and cowpea (Vigna unguiculata [L.] Walp.) were highly productive warm season legumes but may include more production risk in green manure systems due to soil moisture competition.

Impacts of Micro- and Nano-Plastics on Soil Properties and Plant Production in Agroecosystems: A Mini-Review

Micro- and nano-plastics (MNPs) are tiny plastic particles resulting from plastic product degradation. Soil MNPs have been identified as potential influential factors affecting various soil properties and crop biomass productivity. This mini-review provides a synthesis of recent findings concerning their effects on soil physicochemical properties, microorganisms, organic carbon content, soil nutrients, greenhouse gas emissions, soil fauna, and their impacts on plant ecophysiology, growth, and production. The results indicate that MNPs may markedly impede soil aggregation ability, increase porosity, decrease soil bulk density, enhance water retention capacity, influence soil pH and electrical conductivity, and escalate soil water evaporation. Exposure to MNPs may predominantly induce changes in soil microbial composition, reducing the diversity and complexity of microbial communities and microbial activity while enhancing soil organic carbon stability, influencing soil nutrient dynamics, and stimulating organic carbon decomposition and denitrification processes, leading to elevated soil respiration and methane emissions, and potentially decreasing soil nitrous oxide emission. Additionally, MNPs may adversely affect soil fauna, diminish seed germination rates, promote plant root growth, yet impair plant photosynthetic efficacy and biomass productivity. These findings contribute to a better understanding of the impacts and mechanistic foundations of MNPs. Future research avenues are suggested to further explore the impacts and economic implications.

Physico-Chemical Analysis of Soils Used for Pineapple Cultivation in the Sub-Prefectures of Maferinyah and Friguiagbé (Prefectures of Forécariah and Kindia) Republic of Guinea

Over the years, pineapple production in the Republic of Guinea has become less competitive in the West African sub-region, with a world ranking of 144th. It is therefore only natural to review certain parameters in order to improve this ranking. To do this, certain physico-chemical parameters of soil samples from Friguiagbé and Maferinyah (in the Kindia and Forécariah prefectures) were taken and analysed using the following techniques: Pipette de Robinson, Anne, Bray II, Kapen HICDVITZ, Mc. Lead (1982). The analytical results show that the soils at Friguiagbé in Kindia and Maferinyah in Forécariah are acidic, with pH values of 4.4 and 4.7 (fields I and II) and 4.8 and 4.7 (fields I and II) respectively. The soils have a silty-sandy texture. This study could therefore serve as a guide for the Ministry of Agriculture of the Republic of Guinea.

Crop Yield and Soil Properties in the First 3 Years After Biochar Application to a Calcareous Soil

It remains unclear whether biochar applications to calcareous soils can improve soil fertility and crop yield. A long-term field experiment was established in 2009 so as to determine the effect of biochar on crop yield and soil properties in a calcareous soil. Five treatments were： 1） straw incorporation; 2） straw incorporation with inorganic fertilizer; 3）, 4） and 5） straw incorporation with inorganic fertilizer, and biochar at 30, 60, and 90 t ha-l, respectively. The annual yield of either winter wheat or summer maize was not increased significantly following biochar application, whereas the cumulative yield over the first 4 growing seasons was significantly increased. Soil pH, measured in situ, was increased by a maximum of 0.35 units after 2 yr following biochar application. After 3 yr, soil bulk density significantly decreased while soil water holding capacity increased with adding biochar of 90 t ha^-1. Alkaline hydrolysable N decreased but exchangeable K increased due to biochar addition. Olsen-P did not change compared to the treatment without biochar. The results suggested that biochar could be used in calcareous soils without yield loss or significant impacts on nutrient availability.

Treated wastewater irrigation effect on soil,crop and environment:Wastewater recycling in the loess area of China

A study was carded out at the Loess Plateau in Dongzhi, China, to test the feasibility of using secondary treatment sewage effluent and to determine whether the water quality would then meet the recommended irrigation norm. Seven crops, including celery, wheat, maize, millet, apples, rapeseed and yellow beans, were tested in the study. Physical and chemical properties of the soil, crop yield and quality and leachate at different soil depths were measured. In most cases, the quality of the crops that made use of treated sewage was not distinctively different from those that did not use treated sewage. However, yields for the former were much higher than they were for the latter. Leachates at different soil depths were analyzed and the results did not show alarming levels of constituents. For a period of approximately 14 months, the treated sewage irrigation had no significant effect on the loess soil and no cases of illness resulting from contact with the treated sewage were reported. With treated sewage irrigation, a slight increase in the organic content of the soil was observed.

Effect of Long-Term Application of K Fertilizer and Wheat Straw to Soil on Crop Yield and Soil K Under Different Planting Systems

Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied. The experiments on long-term application of K fertilizer and wheat straw to soil in Hebei fluvo aquic soil and Shanxi brown soil in northern China were begun in 1992. The results showed that K fertilizer and straw could improve the yields of wheat and maize with the order of NPK ＋ St 〉 NPK 〉 NP ＋ St 〉 NP, and treatment of K fertilizer made a significant difference to NP, and the efficiency of K fertilizer in maize was higher than in wheat under rotation system of Hebei. In contrast with Shanxi, the wastage of soil potassium was a more serious issue in the rotation system in Hebei, only treatment of NPK ＋ St showed a surplus of potassium and the others showed a wane. K fertilizer and straw could improve the content of water-soluble K, nonspecifically adsorbed K, non-exchangeable K, mineral K, and total K in contrast to NP; however, K fertilizer and straw reduce the proportion of mineral K and improve proportion of other forms of potassium in the two locating sites. Compared with the beginning of orientation, temporal variability character of soil K content and proportion showed a difference between the two soil types; furthermore, there was a decrease in the content of mineral K and total K simultaneously in the two locating sites. As a whole, the effect of K fertilizer applied to soil directly excelled to wheat straw to soil. Wheat straw to soil was an effective measure to complement potassium to increase crop yield and retard the decrease of soil K.

An united model and simulation of nitrogen transport, uptake and transformation in soil-crop system

Based on the simulation experiments of water and nitrogen transport, transformation and uptaking, under the condition of different cropping pattern of winter wheat in the greenhouse and the condition of different wastewater irrigation plan. An united computing model of crop growth, distribution of roots, water and nitrogen uptaking by roots and transformation in soil crop system was developed. Growth status of crops, root growth condition and water, nitrogen uptaking pattern by roots under different watering and N pollution conditions were simulated and analyzed due to the development of this mathematical model and the identification of parameters and boundary conditions in the greenhouse, so that it provided a primary computing method for selecting an efficient, productive watering and wastewater irrigating plan.

Assessment of Long-Term Compost Application on Physical, Chemical, and Biological Properties, as Well as Fertility, of Soil in a Field Subjected to Double Cropping

The aim of this article was to assess the influence of long-term application of compost on the physical, chemical, and biological properties, as well as the fertility, of soil in a field subjected to double cropping (paddy rice and barley), mainly by integrating previous studies of the effects of compost and manure on soil qualities. Continuous compost application, especially at a high level (30 Mg·ha-1·y-1), into the double cropping soils increased the activities of organic C-, N-, and P-decomposing enzymes and the contents of organic C, total N, and microbial biomass N, as well as the cation exchange capacity, thereby contributing to the enhancement of soil fertility. Also, the compost application increased the degree of water-stable soil macroaggregation (>0.25 mm), which was correlated significantly (r > 0.950, p < 0.05) with the contents of hydrolyzable carbohydrates (with negative charge) and active Al (with positive charge), and resulted in the modification of soil physical properties. Furthermore, the application increased the amount of soil organic matter, including humic acid with a low degree of darkening and fulvic acid, and contributed to C sequestration and storage. Physical fractionation of soil indicated that about 60% of soil organic C was distributed in the silt-sized (2 - 20 μm) aggregate and clay-sized (<2 μm) aggregate fractions, while about 30% existed in the decayed plant fractions (53 - 2000 μm). The results obtained unambiguously indicate that long-term application of compost can improve soil qualities in the field subjected to double cropping, depending on the amount applied.

Soil carbon sequestration under long-term rice-based cropping systems of purple soil in Southwest China

Carbon sequestration in agricultural soils is a complex process controlled by farming practices, climate and some other environment factors. Since purple soils are unique in China and used as the main cropland in Sichuan Basin of China, it is of great importance to study and understand the impacts of different fertilizer amendments on soil organic carbon（SOC） changes with time. A research was carried out to investigate the relationship between soil carbon sequestration and organic carbon input as affected by different fertilizer treatments at two long-term rice-based cropping system experiments set up in early 1980 s. Each experiment consisted of six identical treatments, including（1） no fertilizer（CK）,（2） nitrogen and phosphorus fertilizers（NP）,（3） nitrogen, phosphorus and potassium fertilizers（NPK）,（4） fresh pig manure（M）,（5） nitrogen and phosphorus fertilizers plus manure（MNP）, and（6） nitrogen, phosphorus and potassium fertilizers plus manure（MNPK）. The results showed that annual harvestable carbon biomass was the highest in the treatment of MNPK, followed by MNP and NPK, then M and NP, and the lowest in CK. Most of fertilizer treatments resulted in a significant gain in SOC ranging from 6.48 to 2 9.13% compared with the CK, and raised soil carbon sequestration rate to 0.10–0.53 t ha–1 yr-1. Especially, addition of manure on the basis of mineral fertilizers was very conducive to SOC maintenance in this soil. SOC content and soil carbon sequestration rate under balanced fertilizer treatments（NPK and MNPK） in the calcareous purple soil（Suining） were higher than that in the acid purple soil（Leshan）. But carbon conversion rate at Leshan was 11.00%, almost 1.5 times of that（7.80%） at Suining. Significant linear correlations between soil carbon sequestration and carbon input were observed at both sites, signifying that the purple soil was not carbon-saturated and still had considerable potential to se questrate more carbon.

Effects of Different Cropping Patterns of Soybean and Maize Seedlings on Soil Enzyme Activities and MBC and MBN

Through the pot experiment, the effects of different cropping patterns of soybean and maize seedlings on rhizosphere soil urease, catalase, polyphenol oxidase and invertase activities and microbial biomass carbon （MBC） and nitrogen （MBN） were studied. Six treatments of soybean-soybean, soybean-maize, soybean-mixed, maize-soybean, maize-maize and maize-mixed were conducted in pots. Results showed that catalase activity and invertase activity of maize-maize were the highest and significantly different from those of the other treatments except maize-soybean; soil polyphenol oxidase activity of soybean-maize was the highest, and reached significant level among the other treatments, but there was no significant difference of urease activity among treatment soils; MBC of maize-maize soil and MBN of maize-mixed soil reached the highest and significant levels compared with other treatments; MBC and C/N ratio had positive and very significant correlations with soil catalase activity and invertase activity, respectively. Therefore, different cropping patterns could affect rhizosphere soil enzyme activities and soil MBC and MBN, which influenced soil carbon and nitrogen mineralization.

Long-term rice-based cropping system effects on near-surface soil compaction

Irrigated rice (Oryza sativa L.) production is as-sociated with frequent cycling between anaero-bic and aerobic conditions, which can lead to a greater rate of soil organic matter (SOM) de-composition, thus potentially increasing soil bulk density (BD) over time. A study was con-ducted in the Mississippi River Delta region of eastern Arkansas, USA to evaluate the long-term effects of rice-based crop rotations, tillage [conventional tillage (CT) and no-tillage (NT)], soil fertility regime (optimal and sub-optimal), and soil depth (0-10 and 10-20 cm) after 10 years of consistent management on near-surface soil compaction, as measured by BD. Soil BD was greater under NT than CT in the top 10 cm, but was similar between NT and CT in the 10- to 20-cm depth interval. Soil BD differed among common rice-based cropping systems with corn, soybean, and winter wheat, but few consistent trends were evident. It appears that, even after 10 years of continuous CT or NT rice production on a silt-loam soil, substantially increased near-surface soil BD has not occurred to the point where soil compaction would be a likely culprit responsible for a reduced early season stand establishment or crop yield differences among rice-based copping systems.

The Role of Cover Crops towards Sustainable Soil Health and Agriculture—A Review Paper

Cover crops are the plants which are grown to improve soil fertility, prevent soil erosion, enrichment and protection of soil, and enhance nutrient and water availability, and quality of soil. Cover crops provide several benefits to soils used for agriculture production. Cover crops are helpful in increasing and sustaining microbial biodiversity in soils. We summarized the effect of several cover crops in soil properties such as soil moisture content, soil microbial activities, soil carbon sequestration, nitrate leaching, soil water, and soil health. Selection of cover crops usually depends on the primary benefits which are provided by cover crops. Other factors may also include weather conditions, time of sowing, either legume or non-legume and timing and method of killing of a cover crop. In recent times, cover crops are also used for mitigating climate change, suppressing weeds in crops and increasing exchangeable nutrients such as Mg2+ and K+. Cover crops are also found to be economical in long-term experiment studies. Although some limitations always come with several benefits. Cover crops have some problems including the method of killing, host for pathogens, regeneration, and not immediate benefits of using them. Despite the few limitations, cover crops improve the overall health of the soil and provide a sustainable environment for the main crops.

Changes in Soil Enzyme Activity and Nutrient Content in Different Years of Continuous Cropping Tobacco Fields

In order to find out changes in the main fertility indicators of continuous cropping tobacco fields in Henan Province with years of continuous cropping,5 typical tobacco fields( Jia County,Shaoling District,Fangcheng County,Xiangcheng County,and Song County) were studied. Indicators in question included activity of main enzymes( sucrase,urease,catalase,and acid phosphatase),p H value,organic matters,total nitrogen,available phosphorus and available potassium. The results indicate that in most tobacco fields,the activity of sucrase and urease increased in two years of continuous cropping,later,it showed a declining trend with increase in years of continuous cropping; in some fields,it directly declined with increase in years of continuous cropping; the activity of catalase increased in two years of continuous cropping,later,it showed a declining trend with increase in years of continuous cropping,and it became stable after three years of continuous cropping;generally,the activity of acid phosphatase declined with increase in the years of continuous cropping within 3 years continuous cropping,later,it became stable. Except Fangcheng County,the soil p H value of other districts( counties) generally declined with increase in years of continuous cropping,and it was in the range of 5. 6-6. 8. With the increase in continuous cropping,the soil organic matters( SOM) in tobacco fields of Jia County and Song County declined,changes of SOM in tobacco fields of Fangcheng County and Xiangcheng County were not obvious,and SOM showed the trend of first decline then rise in Shaoling District. In most tobacco fields( Jia County,Xiangcheng County,and Song County),the total nitrogen showed a declining trend; in Shaoling District,it showed a trend of first decline then rise; in Fangcheng County,it showed a rising trend. The available phosphorus firstly slightly declined then rose in tobacco fields of Shaoling District and Song County; it showed a trend of first rise then decline in Jia County; there were no obvious changes in Fangcheng County and Xiangcheng County. Changes in the available potassium were different in tobacco fields. In sum,there are certain rules for changes in soil enzyme activity and nutrient content in tobacco fields in Henan Province,but changes are not completely the same. It is concluded that the site conditions and farming activities exert a certain influence on soil enzyme activity,p H value,organic matters,and nitrogen,phosphorus and potassium content. Therefore,to solve obstacles in continuous cropping of tobacco fields,different regions should take different measures.

The effect of total carbon on microscopic soil properties and implications for crop production

Soil structure is a dynamic property affected by physical, chemical, and microbiological processes. Addition of organic matter to soils and the use of different management practices have been reported to impact soil structure and crop production. Moderation in soil temperature and increases in microbial activity and soil water retention are often suggested as reasons for the rise in crop yield when organic matter is added to the soil. Less is known about the direct effect of changes in soil structure on crop production. A field experiment was conducted to study the effect of summer cover crop and in-season management system on soil structure. The experiment was a nested design with summer cover crop as the main plot and management system as the subplot. Summer cover crop treatments included cowpea （Vigna unguiculata L. Walp.） incorporated into the soil in the fall （CI）, cowpea used as mulch in the fall （CM）, sudangrass （Sorghum vulgare） incorporated into the soil in the fall （S）, and dry fallow or bare ground （B）. Management systems were organic （ORG） and conventional （CNV） systems. Lettuce （Lactuca sativa L.） and cantaloupes （Cucumis melo L.） were cultivated in rotation in the plots for three consecutive years using the same cover crops and management systems for each plot. Disturbed and undisturbed soil cores were collected at the end of the third year and used for laboratory experiments to measure physical, chemical, and hy- draulic properties. Image analysis was used to quantify soil structure properties using a scanning electron micro- scope on thin sections prepared from the undisturbed soil cores. We found that total soil carbon was correlated with porosity, saturation percentage, and pore roughness. Pore roughness was correlated with crop production in gen- eral and with marketable production in particular. We found that the higher the complexity of the pore space, the more water retained in the soil, which may increase soil water residence and reduce plant water stress.

Bioavailability of crops to environmental hormone Pb in soils and its remediation

Lead (Pb), as an environmental hormone, acts as an estrogen in animal and human bodies, and its envi- ronmental pollution can result in many procreant anomalies, such as maladjustment of incretion, weakening of pro- creation function and descending of genital immunity. Experiments on pot-growth of paddies and corns in this study indicated that these crops did not show any macro-toxic symptoms in the observed contents of Pb added (0–4000 mg/kg) in soils. However, lead in soils can be easily absorbed by crops and accumulated in the different parts of plants. Statistical analysis showed that Pb contents in the crops are strongly positively correlated to the Pb contents in soils. In the crops, the Pb contents of roots are highest, tens to thousands of times those of straws and seeds. It is suggested that the root is a barrier of Pb absorbed by straws and seeds. Based on this fact, Pb pollution in soils can be gradually reduced by planting crops and subsequently removing the roots from the soil. This biotechnology may be used in environmental remediation, which embraces the quality of sustainable agricultural economy and a healthy environment.

Variation of Physical and Chemical Properties of Soils under Different Cropping Systems in the Watershed of Kpocomey, Southern Benin

Soils degradation is one of the constraints in food security achievement in Benin. This study aimed at assessing the effect of cropping systems and slope on soil physical and chemical properties in the watershed of Kpacomey located in the Aplahoué district. Soil samples were collected from three parallel transects along the slope. Sampling was carried out under different treatments combining cropping systems (Maize-Cassava, pure Palm grove, Palm grove-Maize-Cassava and Teak Plantation) along with slope levels (low slope, medium slope and high slope degree). The impact of cropping systems and slope on soil properties was assessed by determining the physical and chemical parameters. The cropping systems significantly (p < 0.05) influenced soil bulk density, root biomass, soil acidity and soil organic matter. The lowest soil bulk density (1.38 g/cm3) was recorded under the Palm grove-Maize-Cassava cropping system while the highest (1.47 g/cm3) was obtained with pure Palm grove cropping system. Root biomass was more abundant (0.28%) with the pure Palm grove cropping system. However, root biomass was significantly (p < 0.05) influenced by slope. Soil crusting resulted in no significant influence (p > 0.05) on the effect of cropping systems and slope. Moreover, cropping systems resulted in significant effects (p < 0.05). Soil organic matter and soil-assimilated phosphorus content were significantly influenced by the effect of the slope. These findings indicated that cropping systems and slope are significant drivers in soil degradation in the Kpacomey watershed and bringing out cropping systems that best aim at soil conservation.

The Removal and Remediation of Phenanthrene and Pyrene in Soil by Mixed Cropping of Alfalfa and Rape

The mechanisms and efficiencies of the removal and remediation of polycyclic aromatic hydrocarbons （PAHs） in soils by different planting patterns with rape （Brassica campestris） and alfalfa （Medicago sativa） were studied by pot experiments in a greenhouse. Results showed that the remediation efficiencies under mixed cropping of alfalfa and rape significantly exceeded those under single cropping when the initial concentrations of phenanthrene and pyrene were at 20.05-322.06 mg kg^-1 and 20.24-321.42 mg kg^-1, respectively. After 70 days plantation of crops, the contents of extractable PAHs in soils under mixed cropping were much lower than those under single cropping. About 65.17-83.52% of phenanthrene and 60.09%- 75.34% ofpyrene was removed from the soils under mixed cropping, respectively, which were averagely 43.26 and 40.38% for phenanthrene, and 11.03 and 16.29% for pyren higher than those under single cropping. Alfalfa or rape did absorb and accumulate PAHs from the soils apparently; the PAHs concentrations in plants monotonically increased with the increase of initial PAHs concentrations in soil; the accumulations of PAHs in plants showed following sequence as roots 〉 above parts, phenanthrene 〉 pyrene and single cropping 〉 mixed cropping at same contamination level. Despite the presence of vegetation significantly enhanced the remediation of PAHs in soils, contributions of abiotic loss, plant uptake, accumulation and microbial degradation was much lower than those of plant-microbial interactions in the process of phytoremediation. Thus plant-microbial interactions are the main mechanisms for the remediation enhancement of soil PAHs pollution under mixed cropping models. Results suggested a feasibility of the establishment of multi-species phytoremediation for the improvement of remediation efficiencies of PAHs, which may decrease accumulations of PAHs in crops and thus reduce their risks.

Effects of level soil bunds and stone bunds on soil properties and its implications for crop production: the case of Bokole watershed, Dawuro zone, Southern Ethiopia

Level soil bunds (LSB) and stone bunds (SB) have been widely implemented in the Bokole watershed since 2000 through support of the World Food Program (WFP). However, the performance of them against the target of the structure has not been studied. This study analyzed the effect of LSB and SB on selected soil properties, when compared with nonterraced cropland. The Bokole watershed was divided into two units. From upper watershed, three croplands with LSB (aged 4, 6, and 9 years) and three nonterraced croplands each adjacent to one of the LSB were selected. Similarly, in lower watershed, SB aged 4, 6, and 8 years and three nonterraced croplands each adjacent to one of the SB were selected. From each cropland with LSB and SB, three composite soil samples (rep licates) were collected systematically in X designed rectangular plot. From each nonterraced cropland, three composite soil samples (replicates) were collected in X designed square plot. A total of 36 soil samples were analyzed for Soil Organic Carbon (SOC), Total Nitrogen (TN), Available Phosphorus (AP), Available Potassium (AK), pH, and Cation Exchange Capacity (CEC) following standard laboratory procedures. Most soil parameters were not significantly different in cropland with LSB and SB compared to nonterraced. However, in LSB aged 4 years and SB aged 6 years AP and pH were significantly less than their adjacent-nonterraced cropland. In SB aged 8 years, SOC, AP, AK, and pH were also significantly less than adjacent-nonterraced cropland. Past erosion, and past land uses are likely factors contributed to the observed result. It was inferred that the mean con tribution of LSB and SB alone for crop production with regard to analyzed soil parameters was not significant in the considered sites. Additional soil fertility management practices should be incorporated for better effect.

Study on Obstacles to Continuous Cropping of Vegetables and Soil Remediation Technology

Firstly,this paper analyzes the cause of obstacles to continuous cropping of vegetables,and then introduces the soil ecological remediation technology used for overcoming obstacles to continuous cropping of vegetables. Finally,this paper analyzes the effect of applying soil ecological remediation technology in overcoming obstacles to continuous cropping of vegetables.