Long-Term Impacts of Cover Crops, Chicken Litter, and Crop Rotations on Soil Health in No-Till Systems

Identification of management practices that can improve soil health is critical to improving the sustainability of soybean [Glycine max (L.) Merr.] production. The objective of this study was to examine the long-term effects of continuous soybean, corn-soybean, and soybean-cotton rotations with chicken litter and cover crops (hairy vetch, wheat, fallow) on soil health parameters, including nutrient accumulation and soil organic matter dynamics under a split plot design. The depth intervals of soil sampling were 0 - 15, 15 - 30, 30 - 60, and 60 - 90 cm. Chicken litter resulted in 62.1% and 32.8% higher water extractable organic soil N content than fallow and wheat, respectively, in the surface 0 - 15 cm of soil only. However, there was no significant difference in 1-day Solvita respiration, water extractable organic C, C/N ratio, health score, moisture, earthworm, organic matter, pH, or CEC of soil among fallow, hairy vetch, chicken litter, and wheat regardless of soil depth. Unexpectedly, annual application of chicken litter at 4.4 Mg ha−1 as an N source or growing a winter-season cover crop such as hairy vetch or wheat for continuous 16 years did not significantly increase soil organic matter or water extractable organic soil C. Annual application of chicken litter at 4.4 metric tons (Mg) ha–1 for 16 years increased soil nitrate-nitrogen (NO3−-N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), and zinc (Zn) contents by 92%, 400%, 134%, 20%, 43%, 206%, and 430% in 0 - 15 cm depth compared with their initial soil values, respectively, extracted with Haney H3A-2 (2 g L–1 lithium citrate + 0.6 g L–1 citric acid + 0.4 g L–1 malic acid + 0.4 g L–1 oxalic acid) solution. The increases enhanced soil supply of these nutrients to following crops, but also increased the risks of losing them to the environment. Hairy vetch caused higher H3A extracted soil manganese (Mn) content than fallow and chicken litter in 0 - 60 cm. There was no significant difference in 1-day Solvita respiration, water extractable organic C and N, health score, moisture, organic matter, pH, CEC, or population of earthworm of soil among continuous soybean, corn-soybean, and soybean-cotton in any soil depth. Another major finding of this study was that continuous soybean exerted no adverse effect on soil health relative to the commonly used corn (Zea mays L.)-soybean and soybean-cotton (Gossypium hirsutum L.) rotations under no-tillage after 16 years. To mitigate the risks of nutrient runoff and leaching from long-term chicken litter application, we recommend reducing litter application rates and integrating cover crops into crop rotations to enhance nutrient cycling and reduce environmental impacts.

How Land Use Policies Are Transforming Shifting Cultivation to Short Fallow Systems and Permanent Cultivation of Annual Crops in Tanzania

Recent studies show that shifting cultivation in Tanzania has transformed into more intensive farming practices. One of the drivers of this shift is the implementation of policies that favor sedentary farming. However, there is inadequate information on how this transformation operates at the village level. Based on a case study of one village in Central Tanzania, this study demonstrates that the village land use plan is the primary policy tool for the transformation and intensification of shifting cultivation at the village level. Through the land use planning process, land is allocated only for lawful uses such as settlement, permanent cultivation, and the village forest reserve. No land is designated for shifting cultivation. Additionally, the land use plans are accompanied by by-laws that restrict shifting cultivation practices, such as the use of fire during land preparation and leaving the land fallow for more than 3 years. The intensification of shifting cultivation was not associated with an increase in the use of farm inputs such as improved seeds, fertilizer, or irrigation, as is commonly practiced in sustainable intensive agriculture. Instead, it was associated with the adoption of short fallow farming systems and labor-intensive land preparation methods, such as deep plowing to loosen the soil and sub-soiling vegetation.

Experimental Study on No-tillage Cultivation of Flowering Chinese Cabbage in Rice Winter Fallow Fields

The research made comparisons on no-tillage cultivation and ploughing cultivations of Flowering Chinese cabbage on one-season paddy fields and explored the effects of no-tillage cultivation of Flowering Chinese cabbage on survival rate, insect damages, production cost, yield and benefits of plants. The results indicated that no-tillage cultivation reduced the injured rate of Flowering Chinese cabbage by cutworms, and production cost, but crop yield and output value declined as well. Specifically, yield in the treatment as per no-tillage cultivation lowered by 10.3% and 11.9% compared with the treatments by machine-based ploughing and manual ploughing, and the production interests declined by 11.9% and 11.1%, accordingly.

Autumn Daily Characteristics of Land Surface Heat and Water Exchange over the Loess Plateau Mesa in China

The Loess Plateau, located in northern China, has a significant impact on the climate and ecosystem evolvement over the East Asian continent. In this paper, the preliminary autumn daily characteristics of land surface energy and water exchange over the Chinese Loess Plateau mesa region are evaluated by using data collected during the Loess Plateau land-atmosphere interaction pilot experiment （LOPEX04）, which was conducted from 25 August to 12 September 2004 near Pingliang city, Gansu Province of China. The experiment was carried out in a region with a typical landscape of the Chinese Loess Plateau, known as ＂loess mesa＂. The experiment＇s field land utilizations were cornfield and fallow farmland, with the fallow field later used for rotating winter wheat. The autumn daily characteristics of heat and water exchange evidently differed between the mesa cornfield and fallow, and the imbalance term of the surface energy was large. This is discussed in terms of sampling errors in the flux observations-footprint; energy storage terms of soil and vegetation layers; contribution from air advections; and low and high frequency loss of turbulent fluxes and instruments bias. Comparison of energy components between the mesa cornfield and the lowland cornfield did not reveal any obvious difference. Inadequacies of the field observation equipment and experimental design emerged during the study, and some new research topics have emerged from this pilot experiment for future investigation.

Species diversity,population structure and regeneration of woody species in fallows and mature stands of tropical woodlands of southeast Angola

This study in the dry tropical woodlands of SE Angola in Cuando-Cubango Province assessed the diversity and composition of woody species in fallows compared to those in mature woodlands. We assessed the population structure of the most harvested woody species by calculating size class distribution and evaluated their regeneration potential based on the density of saplings. The vegetation was surveyed in 20 plots of 20 × 50 m(1000 m2). In each plot, we measured the diameter at breast height(DBH) of all woody species with DBH ≥ 5 cm. The saplings were counted, identified and recorded; 718 individuals, corresponding to 34 species in 32 genera and 15 families were recorded. The size class distribution of target woody species showed three different patterns in fallows and mature woodlands. In general,most of the smaller diameter classes had more individuals than the larger ones did, showing that the regeneration may take place. However, in some diameter classes, the absence of larger stems indicated selective logging of larger trees. Few saplings were recorded in the fallows or mature woodlands; fire frequency and intensity is probably the main obstacle for seed germination and seedling survival rates in the studied area.

Soil aggregation and aggregate associated organic carbon and total nitrogen under long-term contrasting soil management regimes in loess soil

This study investigated the effects of three contrasting soil management regimes and different nutrient treatments on the distribution of water-stable aggregates（〉2, 1–2, 0.5–1, 0.25–0.5, and 〈0.25 mm） and associated soil organic carbon（SOC） and total nitrogen（TN） content in loess soil. A 21-yr long-term experiment was performed, in which soil management regimes include cropland abandonment（Abandonment）, bare fallow（Fallow） and wheat-fallow cropping（Cropping）. Under Cropping, the following nutrient treatments were employed： control（CK, no nutrient input）, nitrogen only（N）, nitrogen and potassium（NK）, phosphorus and potassium（PK）, NP, NPK, and manure（M） plus NPK（MNPK）. Results demonstrated that Abandonment significantly increased the content of soil macro-aggregates（〉0.25 mm） and mean weight diameter（MWD） at 0–10 and 10–20 cm soil horizons compared with Cropping, whereas Fallow yielded lower values of above two parameters. Abandonment increased SOC and TN contents in all aggregate sizes by 17–62% and 6–60%, respectively, at 0–10 cm soil layer compared with Cropping. Conversely, Fallow decreased SOC and TN contents in all aggregates by 7–27% and 7–25%, respectively. Nevertheless, the three soil management regimes presented similar SOC contents in all aggregates at 10–20 cm soil horizon. Only Cropping showed higher TN content in 〉0.5 mm aggregates than the two other regimes. Consequently, Abandonment enhanced the partitioning proportions of SOC and TN in 〉1 mm macro-aggregates, and Fallow promoted these proportions in micro-aggregates compared with Cropping. Under Cropping, long-term fertilization did not affect the distribution of aggregates and MWD values compared with those under CK, except for NPK treatment. Fertilizer treatments enhanced SOC and TN contents in aggregates at all tested soil depths. However, fertilization did not affect the partitioning proportions of SOC and TN contents in all aggregates compared with CK. Comprehensive results showed that different soil management regimes generated varied patterns of SOC and TN sequestration in loess soil. Abandonment enhanced soil aggregation and sequestered high amounts of SOC and TN in macro-aggregates. Long-term amendment of organic manure integrated with NPK maintained soil aggregate stability and improved SOC and TN sequestration in all aggregates in loess soil subjected to dryland farming.

Remediation Effects of Water Management and Lime Application on Seasonally-Fallowed Cd-Contaminated Paddy Fields

In the light of the national policy of fallow, this study was conducted to determine how the different water management and lime application would affect soil physical and chemical properties, rice yield and cadmium （Cd） content of rice in fallow season. The results showed that, compared with the arid fallow, the waterlogging fallow decreased the soil pH value whereas signifcantly increased the soil organic matter content and the cation exchange quantity, and reduced the soil effective cadmium content and the rice cadmium content whereas could increase the rice yield to a certain extent. In the fooded fallow or the dry fallow, the application of lime mainly depended on the alkali conditioning of lime and the antagonistic effect of Ca2＋, which could signifcantly reduce the cadmium content of rice, and its effect would increase linearly with the increase of lime dosage, whereas had no significant effect on soil organic matter content and cation exchange quantity. In order to establish a linear equation of lime dosage and related indexes under the condition of waterlogging fallow or dry fallow, calculations showed that each application of lime at 1 000 kg/hm2 or kg/hmss2 could improve soil pH value by 0.238 2 or 0.246 5units respectively, and reduce the effective Cd content to 0.007 5 mg/kg both in the arid fallow and the waterlogging fallow conditions. The lime theoretic application rate for the lowest Cd content of late rice in the arid fallow was 5 120 kg/hm2, and the minimum limit of the Cd content in rice was 0.124 2 mg/kg; and the lime theoretic application rate for the highest yield of late rice in the submerged water fallow was 4 636 kg/hm2, the minimum theoretic Cd content in rice is 0.100 7 mg/kg, and it could reduce the Cd content in rice under the condition of submerged fallow and decrease the dosage of lime.

Effects of improved fallow with Sesbania sesban on maize productivity and Striga hermonthica infestation in Western Kenya

Striga hermonthica is a major constraint to smallholder sub-sistence agriculture production in the sub-Saharan African region. Low soil fertility and overall environmental degradation has contributed to the build-up of the parasitic weed infestation. Improved cropping systems have to be introduced to address the interrelated problems of S. her-monthica and soil fertility decline. Thus, the effects of improved fallow with leguminous shrub Sesbania sesban on maize yields and levels of S. hermonthica infestation on farm land in the bimodal highlands of western Kenya were investigated. The experimental treatments were arranged in a phased entry, and randomized complete block scheme were six months Sesbania fallow, 18 months Sesbania fallow, six months natural fallow consisting of regrowth of natural vegetation without cultivation, 18 months natural fallow, continuous maize cropping without fertilizer application, and continuous maize cropping with P and N fertilization. Results show that Sesbania fallows significantly （p0.05） increase maize yield relative to continuous unfertilized maize. S. hermonthica plant populations decrease in continuous maize between the first season （mean = 428 000 ± 63 000 ha-1） and second season （mean=51 000 ± 15 000 ha-1）, presumably in response to good weed management. S. hermonthica seed populations in the soil decrease throughout the duration of the experi-ment in the continuous maize treatments. Short-duration Sesbania fal-lows can provide modest yield improvements relative to continuous unfertilized maize, but short-duration weedy fallows are ineffective. Continuous maize cultivation with good weed control may provide more effective S. hermonthica control than fallowing.

Divergent responses of tiller and grain yield to fertilization and fallow precipitation:Insights from a 28-year long-term experiment in a semiarid winter wheat system

Tillering is an important phenological stage,which is strongly related to the yield in spike components and final grain yield during winter wheat growth.Precipitation during the fallow season(fallow precipitation)influences tillering in winter wheat on the semi-arid Chinese Loess Plateau.However,little work has been done regarding tiller number changes under various types of fertilization and amounts of fallow precipitation on a long-term scale.Effects of fallow precipitation and fertilization on tiller were investigated in a winter wheat(Triticum aestivum L.)system in a 28-year field study(1990 to 2017)in a semiarid agro-ecosystem.Tiller number,spike number and grain yield were measured in four fertilization conditions:control without fertilizer(CK);mineral nitrogen fertilizer alone(N);mineral phosphorus fertilizer alone(P);mineral nitrogen and phosphorus fertilizer together(NP).Based on the long-term annual fallow precipitation,dry years(mean annual fallow precipitation)were distinguished.Phosphorus fertilization alone significantly increased the mean annual tiller number(23%),and the increase in tiller number was higher in wet years(29%)than in the dry years(17%).However,nitrogen fertilization alone had little effect on mean tiller number,while nitrogen and phosphorus together significantly increased mean annual tiller number(30%),mean tiller number in wet years(45%)and mean tiller number in dry years(17%).Tiller number was significantly and positively correlated with fallow precipitation in dry years for all fertilizer treatments,whereas it was weakly and either positively or negatively correlated with fallow precipitation in wet years depending on the treatment.This study found positive correlations between tiller number and fallow precipitation in the CK and NP treatments,and it found negative correlations between tiller number and fallow precipitation in the treatments with nitrogen fertilization alone or phosphorous fertilization alone in wet years.Understanding the impacts of fallow precipitation and fertilization on tiller development shed light on ways to improve crop production in rain-fed agricultural regions.

Local records of long-term dynamics of bamboo gregarious flowering in northern Laos and regional synchronicity of Dendrocalamus membranaceus in two flowering sites

Bamboos are widely distributed in mainland Southeast Asia and have abundant biomass. They are characterized by prolonged vegetative growth and semelparity. Where bamboos are dominant, their synchronous flowering and death has a major impact on forest vegetation. Although the small-scale dynamics of this process have become clearer in recent years, the history, geographical scale and synchronicity of bamboo flowering over broad areas remains unknown. This study focused on the flowering history of six bamboo species, Bambusa tulda, Cephalostachyum virgatum, Dendrocalamus hamiltonii, Dendrocalamus membranaceus, Indosasa sinica and Oxytenanthera parvifolia, over 40 years across a broad area of northern Laos. We also examined the synchronicity of flowering in D. membranaceus. We visited 49 villages in northern Laos and surveyed knowledgeable inhabitants about bamboo flowering history. The timing, scale and synchronicity of gregarious flowering varied among species. D. hamiltonii and D. membranaceus showed higher flowering synchronicity than other species. All the species except I. sinica had both sporadic and gregarious flowering traits, and showed conspicuous variability in their flowering scale. The flowering bamboo population at two gregarious flowering sites for D. membranaceus was surveyed. While thisspecies had the highest synchronicity in this study, its synchronicity was lower than other species in previous studies worldwide. We found that the gregarious flowering of bamboos in northern Laos over the last 40 years showed lower synchronicity than bamboo flowering reported in other areas of the world. The historical dynamics and scale of bamboo flowering must be further clarified to understand the vegetation composition of this area.

Modeling habitat suitability and utilization of the last surviving populations of fallow deer(Dama dama Linnaeus,1758)

DüzlerçamıWildlife Reserve Area(WRA)is the last natural habitat of fallow deer(Dama dama)in the world.Fallow deer is native to Turkey,however,its geographical range is currently confined to DüzlerçamıWRA,Antalya.To date,a detailed habitat investigation of fallow deer dis-tribution has not been conducted.This study is vital for the last surviving populations of fallow deer in Turkey.There-fore,we studied the habitat suitability and utilization of fal-low deer in the DüzlerçamıWRA.Vegetation and wildlife inventory was surveyed across a total of 304 sample areas between 2015 and 2017.Plant species were recorded accord-ing to the Braun-Blanquet method and wildlife surveys were based on footprints,feces,and other signs of fallow deer.Classification and regression tree techniques,as well as MAXENT,were used to model vegetation and fallow deer habitat.Topographic position index,terrain ruggedness index,roughness index,elevation,and bedrock formation were also calculated and included in the models.Based on our results,we drafted a habitat protection map for fallow deer.To ensure sustainability of habitats where populations of fallow deer are found in Turkey,we developed recommen-dations such as closuring human access of the 1st-degree Protection Area and reintroduction of the species to other potential habitats.

Estimating Carbon Capture Potential of Fallow Weeds in Rice Cropping Systems

Weeds occurred during the fallow season can well perform the function of carbon(C)capture due to receiving little human disturbance.This study aimed to evaluate the C capture potential of fallow weeds in rice(Oryza sativa L.)cropping systems.A six-region,two-year on-farm investigation and a three-year tillage experiment were conducted to estimate C capture in fallow weeds in rice cropping systems.The on-farm investigation showed that the average mean C capture by fallow weeds across six regions and two years reached 112 g m^(-2).The tillage experiment indicated that no-tillage practices increased C capture by fallow weeds by 80%on average as compared with conventional tillage.The results of this study not only contribute to an understanding of C capture potential of fallow weeds in rice cropping systems,but also provide a reference for including fallow weeds in the estimation of vegetative C sink.

Research on Scientifically and Rationally Promoting the Fallow of Cultivated Land under the Strategy of Rural Revitalization

Implementing the rural revitalization strategy is an important decision-making arrangement made by the party s 19th National Congress,and is the general grasp of the work of"agriculture,rural areas and farmers"in the new era.In rural development,the issue of cultivated land is an important way to promote poverty alleviation in the vast rural areas and build a well-off society in an all-round way.In combination with the fact that the current quality of cultivated land resources in China is not high and the basic fertility has been continuously declining caused due to pollution,China must promote a scientific and rational system of arable land fallow to ensure the further development of agricultural modernization in China.In the process of researching the implementation of the arable land fallow system,the problems of land abandonment and"non-agriculturalization"after farmland fallow,the willingness of farmers to fallow and the subsidy for farmland fallow have been discovered.In response to the problems above,corresponding policy recommendations are put forward in order to better promote the process of arable land fallow and poverty alleviation in China.

Fractal Kinetics Parameters Regulating Carbon Decomposition Rate under Contrasting Soil Management Systems

Agricultural soils can sequester and release large amounts of carbon. Accessibility of soil carbon to microbial attacks depends on biological, chemical, and physical protection mechanisms such as organic matter composition and particle size, soil aggregation, and chemical protection through the silt-clayorganic matter complex. While soil and organic matter are fractal objects controlling exposure of reactive surfaces to the environment, soil aggregation and biomass production and quality are regulated by agricultural practices. Organic matter decomposition in soil is generally described by the classical first-order kinetics equations fitted to define distinct carbon pools. By comparison, fractal kinetics assigns a coefficient to adjust time-dependent decomposition rate of total soil carbon to protection mechanisms. Our objective was to relate fractal parameters of organic matter decomposition to soil management systems. Retrieving published data, the decomposition of organic matter was modeled in a silt loam soil maintained under pasture, annual cropping or bare fallow during 11 years. The classical first-order kinetics model returned quadratic relationships indicating that reactive carbon decreased with time. Fractal kinetics rectified the relationships successfully. Initial decomposition rate (k 1 at t = 1) was 7 × 10-4 for pasture, 1 × 10-4 for annual cropping, and 0.5 × 10-4 for bare-soil fallow. Fractal coefficients h were 0.71, 0.45, and 0.25 for pasture, annual cropping and fallow, respectively. Due to aggregation, physical protection against microbial attacks was highest under pasture management, leading to higher carbon sequestration despite higher biomass production and “priming” effects. Parameters k 1 and h proved to be useful indicators for soil quality classification integrating the opposite effects of labile carbon decomposition and carbon protection mechanisms that regulate the decomposition rate of organic matter with time as driven by soil management practices.

Comparison of Soil Quality Improvement under Different Fallow Types on Dystric Nitosols Derived from Sand Stone in South Western Nigeria

The project was carried out to determine the effects of different fallow types on soil derived from sand stone of low nutrient status in south western Nigeria. The different fallow types include Leu-caena, elephant grass, guinea grass and secondary forest. Cultivated farm land was used to serve as control for comparison of soil quality improvement. Soil samples were collected in four replicates on each land cover type and analyzed for major physical and chemical parameters. The results show little fertility improvement for base saturation with 1.42 cmol/kg in Leucaena, 1.99 cmol/kg in secondary forest, 1.60 cmol/kg in guinea grass and in Elephant grass. Leucaena resulted to better soil quality than secondary forest especially in surface properties though not significantly different. Elephant grass and guinea grass also resulted to better Nitrogen content. Nitrogen content recorded in Leucaena was high with 0.20% - 0.25%. Guinea grass and elephant grass resulted to better soil quality in terms of nitrogen content [0.20% - 0.25%] than cultivated and secondary forest [0.07% - 0.11%] due to their yearly incorporation in to the soil by ploughing. The values of phosphorus were higher in Leucaena though not significant [6.46 mg/kg]. Low soil properties improvement is attributed to nutrient exploitation in Leucaena and secondary forest after a long period of fallow [20 years] while, nitrogen enrichment in the grasses is attributed to yearly tillage. Over all low to medium soil variability indicates that the soils could be managed as a unit for crop production.

Nitrogen Recoveries and Yields Improvement in Cowpea sorghum and Fallow sorghum Rotations in West Africa Savannah

The effects of previous cowpea （Vignaunguiculata） and annual fallow on N recoveries, succeeding sorghum yields and soil properties were studied using a 5-year-old （1995-1999） field experiment at Kouar6 （11°59′ North, 0°19′ West and 850 m altitude） in Burkina Faso. A 3 4 factorial design in a split plot arrangement with three rotation treatments and four fertilizer treatments was used. Total N uptake by succeeding sorghum increased from 26 kg N ha~ in mono cropping of sorghum to 31 and 48 kg N ha~ when sorghum was rotated with fallow or cowpea respectively. Nitrogen derived from fertilizer increased from 10% in mono cropping of sorghum to 22% and 26% when sorghum was rotated with fallow or cowpea respectively. While fallow did not increase N derived from soil, cowpea doubled the quantity of N derived from soil （Ndfs）. Sorghum grain yields increased from 75% and 100% when sorghum was rotated with fallow or cowpea respectively. All rotations treatments decreased soil organic C and N but soil organic C was the highest in fallow-sorghum rotation. It was concluded that cowpea-sorghum rotation was more effective than fallow-sorghum rotation and five management options were suggested to improve traditional system productivity.

Cropping frequency and N fertilizer effects on soil water distribution from spring to fall in the semiarid Canadian prairies

In the semiarid Canadian prairies, water is the most limiting and nitrogen (N) the second most limiting factor influencing spring wheat (Triticum aestivum L.) production. The efficiency of water-and nitrogen use needs to be assessed in order to maintain this production system. The effects of cropping frequency and N fertilization on trends in soil water distribution and water use were quantified for an 18-yr (1967-1984) field experiment conducted on a medium textured Orthic Brown Chernozem (Aridic Haploboroll) in southwestern Saskatchewan, Canada. Soil water contents were measured eight times each year and plant samples were taken at five phenological growth stages. The treatments studied were continuous wheat (Cont W), summer fallow - wheat, F-(W) and summer fallow - wheat - wheat, F-W-(W) each receiving recommended rates of N and phosphorus (P) fertilizer, and (F)-W-W and (Cont W) each receiving only P fertilizer, with the examined rotation phase shown in parentheses. Soil water conserved under fallow during the summer months averaged 25 mm in the root zone, and was related to the initial water content of the soil, the amount of precipitation received, its distribution over time, and potential evapotranspiration. Under a wheat crop grown on fallow, soil water contents between spring and the five-leaf stage remained relatively constant at about 250 mm, but those under a stubble crop, with 40 mm lower spring soil water reserves, increased slightly until about the three-leaf stage. During the period of expansive crop growth (from the five-leaf to the soft dough stage) soil water was rapidly lost from all cropped phases at rates of 1.87 mm.day–1 for F-(W) (N+P), 1.23 mm.day–1 for Cont W (N+P) and 1.17 mm.day–1 for Cont W (+P). The initial loss was from the 0 - 0.3 m depth, but during the latter half of the growing season from deeper depths, although rarely from the 0.9 - 1.2 m depth. In very dry years (e.g., 1973, with 87 mm precipitation between spring and fall) summer fallow treatments lost water. In wet years with poor precipitation distribution (e.g., 1970, with 287 mm precipitation between spring and fall but 142 mm of this in one week between the three- and five-leaf stage) even cropped treatments showed evidence of leaching. The above-ground biomass water use efficiency for Cont W was 19.2 and 16.7 kg.ha–1.mm–1, respectively, for crops receiving (N+P) and P fertilizer only. Grain yield water use efficiency (8.91 kg.ha–1.mm–1) was not significantly influenced by cropping frequency nor N fertilizer. The 18 years of detailed measurements of plant and soil parameters under various crop management systems provide an invaluable source of information for developing and testing simulation models.

Characterization of Woody Vegetation in Different Land Uses in the Commune of Coubalan (Bignona Department, Senegal)

Woody vegetation provides a number of ecosystem services, including soil protection, carbon sequestration and oxygen production. Despite its important role in maintaining ecological balance, woody vegetation is currently undergoing continuous degradation due to climatic hazards and anthropogenic actions. As a result, it is essential to gather information for the sustainable and rational management of woody formations. It is with this in mind that this study aims to contribute to a better understanding of the state of woody vegetation in the different land-use types in Basse Casamance. To this end, stratified random sampling of woody vegetation was carried out in the different land-use types (fields, fallow land and forests) of the Coubalan commune. The sampling unit for fields and fallows was a 2500 m2 plot, and for forests was a 900 m2 plot. A total of 53 species, divided into 48 genera belonging to 22 families, were inventoried in the commune. Structural parameters were higher in the forest, with 1321.3 ± 635.8 individuals/ha, 13.09 ± 0.1 m2 and 79.25% ± 21.08% respectively for observed density, basal area and cover rate. As for dendrometric parameters, they are higher in the fields, with 20.4 ± 13.6 cm and 7.4 ± 3.8 m respectively for trunk diameter and woody height. Fallow land is characterized by species with low dendrometric parameters. These results provide a useful database for rational management of the various land-use types in the commune of Coubalan.

Fertility Reduction in Male Persian Fallow Deer (Dama dama mesopotamica): Inbreeding Detection and Morphometric Parameters Evaluation of Semen

Persian fallow deer (Dama dama mesopotamica) is only found in a few protected and refuges areas in the northwest, north, and southwest of Iran. The aims of this study were analysis of inbreeding and morphometric parameters of semen in male Persian fallow deer to investigate the cause of reduced fertility of this endangered species in Dasht-e-Naz National Refuge, Sari, Iran. The Persian fallow deer semen was collected by an electroejaculator from four adult bucks randomly during the breeding season and from five dehorned and horned deer’s in non-breeding season. Twelve blood samples were taken and mitochondrial DNA was extracted, a non-coding region called d-loop was amplified, sequenced and then were considered for genetic analysis. The Persian fallow deer’s normal and abnormal spermatozoa were similar to that of domestic ruminants but very smaller and difficult to observe at the primary observation. The post-mating season collected ejaculates contained abnormal spermatozoa, debris and secretion of accessory glands in horned bucks and accessory glands secretion free of any spermatozoa in dehorned or early velvet budding bucks. Microscopic evaluation in all four bucks during the mating season showed the mean concentration of 9 × 106 spermatozoa/ml. The mean ± standard deviation of age, testes length and testes width was 4.60 ± 1.52 years, 3.58 ± 0.32 and 1.86 ± 0.09 cm, respectively. The results identified 1120 loci in which 377 were polymorphic. In conclusion, reduced fertility of male Persian fallow deer may be caused by inbreeding of the protected herd in a limited area of Dasht-e-Naz National Refuge.

Extent of Reduction of the Fallow Period and Its Impact on Upland Rice Production in the Nongowa Chiefdom of Kenema District in Eastern Sierra Leone

Slash-and-burn agriculture is the common practice for upland rice intercropping system in Sierra Leone and it has been blamed for the loss of forest vegetation across the country. Shortening of the fallow period in the Eastern region of Sierra Leone has implications on agricultural food production and the persistence of the remaining tropical rainforest. This study was therefore undertaken to assess: 1) the extent of reduction of the fallow period in the Nongowa Chiefdom of Kenema District;2) the causes of reduction in the fallow period;3) farmers’ perception of the relevance of fallow period and the implications of reduction of fallow period on crop production. The study revealed a drastic reduction of the fallow period in the chiefdom with a mean of 3.8 years which falls far below the country mean fallow period of 8.8 years as estimated by FAO. Farmers pointed out that the reduction of the fallow period was as a result of land scarcity due to competing land uses such as large scale commercial agriculture, logging, mining, charcoal burning and expansion of settlements. Farmers agreed that a fallow period of at least 10 years is necessary for upland rice production. Farmers were aware of the impact of reduction of the fallow period on upland rice production and were able to estimate rice yields based on the age of the fallow. Also, farmers have attempted to adapt to the constraints posed by shorter fallow periods by selection of rice varieties to suit the length of the fallow periods.