Net carbon flux from agriculture: Carbon emissions, carbon sequestration, crop yield, and land-use change

There is a potential to sequester carbon in soil by changing agricultural management practices. These changes in agricultural management can also result in changes in fossil-fuel use, agricultural inputs, and the carbon emissions associated with fossil fuels and other inputs. Management practices that alter crop yields and land productivity can affect the amount of land used for crop production with further significant implications for both emissions and sequestration potential. Data from a 20-year agricultural experiment were used to analyze carbon sequestration, carbon emissions, crop yield, and land-use change and to estimate the impact that carbon sequestration strategies might have on the net flux of carbon to the atmosphere. Results indicate that if changes in management result in decreased crop yields, the net carbon flux can be greater under the new system, assuming that crop demand remains the same and additional lands are brought into production. Conversely, if increasing crop yields lead to land abandonment, the overall carbon savings from changes in management will be greater than when soil carbon sequestration alone is considered.     

Crop raiding around Lake Mburo National Park, Uganda

In areas around Lake Mburo National Park, large wild animals wander in close proximity to human settlements. This poses serious conflict in terms of crop damage. The integration of conservation with other land uses is difficult where densely settled agricultural land surrounds a protected area potentially containing problem animals, as is the case for several parks in Africa and Asia. The intensity of crop raiding was quantified through the use of random crop quadrants/plots and area estimation techniques in a portion of raided fields. The animal species concerned were documented from observations, footprints and any other marks left behind. Three variables were tested as predictors of damage: human population density, distance from the park boundary and season. In this study, data is presented regarding crop loss in the different seasons of the year, analysis of crop damage variation and animal species involved in crop loss. A diverse assemblage of animals foraged on subsistence crops and analysis of crop damage revealed significant crop depreciation by wildlife.     

Crop Genetic Resources Diversity and Sustainable Agriculture in Yunnan Province,China

Yunnan is well known as a "Kingdom of Plant". Yunnan is also rich in natural resources of crop. Lots of studies on collection, conservation, protection, evaluation and utilization of crop genetic resources have been done in recent years. But there are some unfavourable factors, too. With the agricultural intensity, some new problem such as decreasing diversity, simplifying varieties and narrowing genetic basis of crop have arisen to restrict the development of agriculture in Yunnan. The only way to achieve a sustainable agriculture in Yunnan is doing our utmost to protect the crop diversity, develop new crop or new varieties and widen the genetic basis of crop varieties.     

Old Crop,New Society: Persistence and Change of Tartary Buckwheat Farming in Yunnan,China

Traditional agricultural systems are important for crop genetic resources conservation. Many scholars have addressed the problem of traditional cultivar replacement by modern varieties, but few have investigated the entire loss of traditional crops from farming systems. Our prior research suggested that tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) agriculture is rapidly decreasing in Yunnan China, the center of the crop’s origin and an important repository of on-farm genetic diversity. Using interdisciplinary methodology to determine whether the crop is indeed in decline and evaluate reasons behind planting trends, we found a combination of interacting agroecological, socio-cultural, and institutional factors influence tartary buckwheat planting in Yunnan. Farmer ethnicity, presence of a commercial market for the crop, and government agricultural policy were particularly important. Low commercial value of the crop compared to other alternatives, reduction of available farmland, and labor shortages were major reasons cited for crop abandonment. Despite an overall reduction in tartary buckwheat planting across a wide spectrum of farms, we also found the crop retains subsistence, rotational and cultural value for many Yunnan farmers. We conclude that although Yunnan farms are increasingly managed commercially rather than for subsistence, tartary buckwheat will continue to occupy a niche in the agricultural landscape.     

Production,harvesting, processing,utilization and economic importance of oats

Oats constitute an important feed grain crop in the United States and many other countries. World production in pounds averages one- third that of wheat and two- fifths that of rice or corn. The United States and Canada produce nearly half of the world crop. Oats are utilized primarily as feed for domestic animals. Although their bone- and muscle- building ingredients and other nutrient values are well known, less than five percent of the world crop is used as human food.     

Prolactin binding activity on the crop sacs of juvenile, mature, parent and prolactin-injected pigeons.

Specific prolactin (PRL) binding activity of lactoperoxidase catalyzed 125I-labeled ovine-PRL was determined in a membrane-rich particulate fraction of pigeon crop sacs. Levels of TSH, LH or FSH as high as 1000 ng each were unable to displace the 125I-o-PRL bound to 600 mug of crop sac microsomal protein, whereas competitive displacement was achieved with as little as 0.5 ng unlabeled PRL. Ovine GH exhibited some cross reactivity when incubated in amounts greater than 500 ng, but this could be accounted for by its stated PRL contamination. Specific PRL binding activities were determined in juvenile and mature pigeons with unstimulated crop sacs, and parent pigeons with 'crop milk' and mature birds injected with PRL for 4 days. Crop sacs from juvenile birds contained approximately twice as much binding activity as crop sacs from mature pigeons. Parent and PRL injected pigeons, each with proliferated crop sac epithelium, exhibited 4-5 times as much specific PRL binding as the non-proliferated crops from juvenile or mature birds. These results show that the pigeon crop sac contains specific binding sites for PRL, and that the crop sac response to PRL is associated with an increase in PRL binding activity.     

Central,but not peripheral,glucagon-like peptide-1 inhibits crop emptying in chicks

We investigated the effect of central and peripheral glucagon-like peptide-1 (GLP-1) on crop emptying in growing chicks. Intracerebroventricular injection of two concentrations of GLP-1 (15 and 60 pmol) similarly suppressed crop emptying, compared with control chicks. The delay in crop emptying induced by GLP-1 (15 pmol) was partly attenuated by co-administration with exendin (5-39) (600 pmol), a GLP-1 receptor antagonist, although exendin (5-39) alone did not affect crop emptying. On the other hand, intraperitoneal administration of several doses of GLP-1 (120, 300 and 3000 pmol) did not alter crop emptying. The present study revealed that central, but not peripheral, GLP-1 inhibits crop emptying in chicks.     

Primate Crop Feeding Behavior,Crop Protection,and Conservation

Many species across a range of primate genera, irrespective of dietary and locomotory specializations, can and will incorporate agricultural crops in their diets. However, although there is little doubt that rapid, extensive conversion of natural habitats to agricultural areas is significantly impacting primate populations, primate crop foraging behaviors cannot be understood solely in terms of animals shifting to cultivated crops to compensate for reduced wild food availability. To understand fully why, how, and when primates might incorporate crops in their dietary repertoire, we need to examine primate crop foraging behavior in the context of their feeding strategies and nutritional ecology. Here I briefly outline current debates about the use of terms such as human–wildlife conflict and crop raiding and why they are misleading, summarize current knowledge about primate crop foraging behavior, and highlight some key areas for future research to support human–primate coexistence in an increasingly anthropogenic world.     

Crop-to-weed gene flow in the genus Sorghum (Poaceae): Spontaneous interspecific hybridization between johnsongrass,Sorghum halepense,and crop sorghum,S. bicolor

The role of crop-to-weed gene flow is often controversial and overlooked. As a consequence, the likelihood of spontaneous crop-to-weed hybridization in most crop/weed systems is generally unknown. The lack of data relating to the formation of crop/weed hybrids has particular contemporary significance when considering the wide scale commercial release of transgenic crop plants and the potential for escape of engineered genes via crop-to-weed hybridization. We created an experimental system whereby we could examine the incidence and rate of spontaneous crop-to-weed hybridization between Sorghum bicolor and S. halepense, johnsongrass. An isozyme marker was used to identify hybrid plants through progeny testing. Incidence and rate of hybridization were highly variable with respect to weed distance from the crop, location of the study site, and year the study was performed. Crop/weed hybrids were detected at distances of 0.5–100 m from the crop. Interspecific hybridization can and does occur in this system at a substantial and measurable rate. Transgenes introduced into crop sorghum can be expected to have the opportunity to escape cultivation through interspecific hybridization with johnsongrass. Traits that prove to be beneficial to weeds possessing them can be expected to persist and spread. This is an issue that needs to be addressed when developing biosafety guidelines for the commercial release of transgenic sorghums.     

Proteinase, amylase, and proteinase-inhibitor activities in the gut of six cockroach species

Representative species, two from each of the cockroach families Blattidae, Blattellidae, and Blaberidae, have similar morphology of the digestive tract but differ in the physiology of digestion. The pH of crop and along the midgut varies in different species from 5.9 to 9.0 and the redox parameter from 10.1 to 12.9. Activities of proteinases and amylases in comparable gut regions differ among the species up to 100 times. Proteolytic activity is high in the midgut and moderate in the crop of Blattidae; in the other species, it is very low in the crop and increases to a moderate level in the posterior half of midgut (PM). The level of amylolytic activity is similar in the examined gut compartments of Blattidae and Blattellidae but low in the PM of Blaberidae. Blaberidae are also characterized by a high potential of the salivary glands, crop, and midgut to inhibit subtilisin, trypsin, and chymotrypsin. Inhibition of these proteinases by the extracts of salivary glands and gut is several orders of magnitude lower and often undetectable in the representatives of Blattidae and Blattellidae.     

Growth,development, and biomass partitioning of the perennial grain crop Thinopyrum intermedium

Intermediate wheatgrass (Thinopyrum intermedium) is a perennial grass that is being domesticated and improved for use as a grain crop. As a perennial grain crop, intermediate wheatgrass has the potential to produce economically viable, food‐grade grain while providing environmental benefits such as reduced erosion and nitrate leaching. To guide agronomic activities for this new crop, more information on intermediate wheatgrass growth and development is needed. We sampled plants every 3–5 days throughout the growing season at three environments to measure growth and development in response to accumulating growing degree days (GDD). A numerical growth index was used to quantify morphological development. Growth index, plant height, biomass, height of the tallest node, and biomass partitioning to leaf, stem, and inflorescence were modelled as a function of GDD. We predicted dates (in GDD and day of the year) for critical morphological events as they relate to grain crop production using model equations. The fraction of total biomass allocated to leaves decreased and stems increased in response to GDD, and both components represented equal proportions of aboveground biomass at plant maturity. Growth and development was similar across environments, but variation in yield components (e.g., 50 seed weight, seed mass inflorescence^?1) was observed. Our results provide the first quantification of growth and development of intermediate wheatgrass, and have application to growers seeking to determine optimal timing of agronomic practices, as well as crop modellers working to integrate new crops into simulation models. As intermediate wheatgrass expands as a perennial grain crop, growth and development should be measured in a broader range of temperature and precipitation conditions.     

Impact of a glossy collard trap crop on diamondback moth adult movement, oviposition, and larval survival

One component of developing a systematic approach for deployment of trap crops is to understand how the trap crop modifies pest behavior. Glossy‐leafed collards, Brassica oleracea L. var. acephala (Brassicaceae), were evaluated as a potential trap crop for diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), because they are attractive to P. xylostella adults and are a poor host for P. xylostella larvae compared to cabbage, Brassica oleracea L. var. capitata. We used large field plots to measure the changes in adult, egg, and larval P. xylostella densities in cabbage when the trap crop was planted in the field. Furthermore, we planted the trap crop in dispersed and concentrated spatial arrangements to determine the impact of trap crop arrangement on the behavior of P. xylostella. In 2002, results showed that the presence of collards within a cabbage field reduced larval density on cabbage. In 2003, neither trap crop arrangement had a significant impact on P. xylostella larval density on cabbage. Adult moths aggregated in proximity to collards in 2002, but not in 2003. Egg and larval data in both years in all treatments showed that total oviposition was highest near a central release point, indicating that females lay many eggs before dispersing very far when suitable host plants are available. The mean direction of P. xylostella movement and oviposition from a central release point was not consistent or correlated to wind direction. Plant size of the trap crop in relation to the main crop and environmental factors may have been responsible for the inconsistent effectiveness of the trap crop.     

Aspects in oat breeding: nutrition quality,nakedness and disease resistance,challenges and perspectives

Traditionally, the oat crop (Avena sativa) has been neglected in a number of respects, cultivated in cropping areas not optimal for wheat, barley or maize. In recent years the interest in oats has increased, particularly because of its dietary benefits and therapeutic potential for human health. The uniqueness and advantages of naked oats over other popular cereals, due to its potentially valuable nutritional composition, have been well studied and reported, opening new market “niches” for oats. Despite the well‐documented benefits, the status of the oat crop is still fragile, due to many reasons. The area cultivated for the oat crop is much less compared with other cereals, and therefore commercial efforts in oat breeding are less. Oat groat yield is lower than other cereals such as wheat and the nutritious uniqueness has not been reflected in agreeable market prices. The same price still exists for both naked and conventional/covered oats in the world grain market. The absence of visible market competitiveness, and some of the oat biological drawbacks, including low grain yield, keeps the oat crop as a lower profitability minor crop. This review is intended to analyse and summarise main achievements and challenges in oat genetics, agronomy and phytopathology to find possible ways of oat improvement and future perspectives for oat breeding.     

Hybridization in agricultural weeds: A review from ecological,evolutionary, and management perspectives

Agricultural weeds frequently hybridize with each other or with related crop species. Some hybrid weeds exhibit heterosis (hybrid vigor), which may be stabilized through mechanisms like genome duplication or vegetative reproduction. Even when heterosis is not stabilized, hybridization events diversify weed gene pools and often enable adaptive introgression. Consequently, hybridization may promote weed evolution and exacerbate weed–crop competition. However, hybridization does not always increase weediness. Even when viable and fertile, hybrid weeds sometimes prove unsuccessful in crop fields. This review provides an overview of weed hybridization and its management implications. We describe intrinsic and extrinsic factors that influence hybrid fitness in agroecosystems. We also survey the rapidly growing literature on crop–weed hybridization and the link between hybridization and invasiveness. These topics are increasingly relevant in this era of genetic tools for crop improvement, intensive and simplified cropping systems, and globalized trade. The review concludes with suggested research priorities, including hybridization in the context of climate change, plant–insect interactions, and redesigned weed management programs. From a weed management perspective, hybridization is one of many reasons that researchers and land managers must diversify their weed control toolkits.     

Soil Health,Crop Productivity,Microbial Transport,and Mine Spoil Response to Biochars

Biochars vary widely in pH, surface area, nutrient concentration, porosity, and metal binding capacity due to the assortment of feedstock materials and thermal conversion conditions under which it is formed. The wide variety of chemical and physical characteristics have resulted in biochar being used as an amendment to rebuild soil health, improve crop yields, increase soil water storage, and restore soils/spoils impacted by mining. Meta-analysis of the biochar literature has shown mixed results when using biochar as a soil amendment to improve crop productivity. For example, in one meta-analysis, biochar increased crop yield by approximately 10 %, while in another, approximately 50 % of the studies reported minimal to no crop yield increases. In spite of the mixed crop yield reports, biochars have properties that can improve soil health characteristics, by increasing carbon (C) sequestration and nutrient and water retention. Biochars also have the ability to bind enteric microbes and enhance metal binding in soils impacted by mining. In this review, we present examples of both effective and ineffective uses of biochar to improve soil health for agricultural functions and reclamation of degraded mine spoils. Biochars are expensive to manufacture and cannot be purged from soil after application, so for efficient use, they should be targeted for specific uses in agricultural and environmental sectors. Thus, we introduce the designer biochar concept as an alternate paradigm stating that biochars should be designed with properties that are tailored to specific soil deficiencies or problems. We then demonstrate how careful selection of biochars can increase their effectiveness as a soil amendment.     

Nematode Economic Thresholds: Derivation,Requirements, and Theoretical Considerations

Determinatitm and use of economic thresholds is considered essential in nematode pest management programs. The economic efficiency of control measures is lnaximized when the difference hetween the crop valne and the cost of pest control is greatest. Since the cost of reducing the nematnde pnpnlation varies with the magnitutle of the reduction attempted, an economic (optimizing) threshold can be determined graphically or mathematically if the nature of the relationships between degree of control and cost, and nematode densities and crop value are known. Economic thresholds then vary according to the nematode control practices used, environmental influences on the nematode damage fnnction, and expected crop yields and values. A prerequisite of the approach is reliability of nematode population assessment techniques.     

Seasonality of standing crop of a Sargassum (Fucales,Phaeophyta) bed in Bolinao,Pangasinan, Philippines

The seasonality of standing crop of a Sargassum bed was investigated by conducting monthly sampling from February 1988 to July 1989. Environmental parameters of water movement, salinity, number of daytime minus tides, and water temperature were also measured. An intra-annual pattern of variation in standing crop of Sargassum crassifolium, S. cristaefolium, S. oligocystum, and S. polycystum was observed. Standing crop was generally lowest in February, March, April, or May, and highest in November through January. Sargassum accounted for about 35 to 85% of the monthly algal standing crop of the bed, and the observed variation in overall standing crop of the bed generally reflected the standing crop of Sargassum. The seasonality of the standing crops of the associated algal divisions also followed an annual cycle, but their maximum and minimum standing crops did not coincide with those of Sargassum. Individually, as well as collectively, the standing crops of the Sargassum spp. were poorly correlated with the environmental factors observed.     

The conflict between vervet monkeys and farmers at the forest edge in Entebbe, Uganda

Forty‐seven property owners in Entebbe, Uganda were questioned about vervet monkey activities on their property. Our main objective was to investigate the interactions between humans and vervet monkeys in an agricultural area adjacent to a forest zone. Other studies have reported that farms located within 300 m of a forested boundary probably incur the greatest risk of crop‐raiding. Two other factors that may influence susceptibility to vervet crop‐raiding were also examined: the types of crops grown and the types of direct preventative measures used. The effect of these two factors on vervet crop‐raiding is not straightforward. However, the distance a property is located from the forest edge is an important factor influencing vervet crop‐raiding. Surveyed gardens 200 m from the forest edge received significantly less crop‐raiding than farms located 100 m or 50 m (P = 0.040, < α = 0.05). We suggest that the development of nonagricultural activities on land directly adjacent to forested areas may reduce vervet crop‐raiding by deterring vervets from travelling greater distances from the forest edge due to increased obstacles or risks.     

Influence of crop type,heterogeneity and woody structure on avian biodiversity in agricultural landscapes

Agriculture is a primary factor underlying world-wide declines in biodiversity. However, different agricultural systems vary in their effects depending on their resemblance to the natural ecosystem, coverage across the landscape, and operational intensity. We combined data from the North American Breeding Bird Survey with remotely sensed measures of crop type and linear woody feature (LWF) density to study how agricultural type, woody structure and crop heterogeneity influenced the avian community at landscape scales across a broad agricultural region of eastern Canada. Specifically, we examined whether 1) avian diversity and abundance differed between arable crop agriculture (e.g., corn, soy) and forage (e.g., hay) and pastoral agriculture, 2) whether increasing the density of LWF enhances avian diversity and abundance, and 3) whether increasing the heterogeneity of arable crop types can reduce negative effects of arable crop amount. Avian diversity was lower in landscapes dominated by arable crop compared to forage agriculture likely due to a stronger negative correlation between arable cropping and the amount of natural land cover. In contrast, total avian abundance did not decline with either agricultural type, suggesting that species tolerant to agriculture are compensating numerically for the loss of non-tolerant species. This indicates that bird diversity may be a more sensitive response than bird abundance to crop cover type in agricultural landscapes. Higher LWF densities had positive effects on the diversity of forest and shrub bird communities as predicted. Higher crop heterogeneity did not reduce the negative effects of high crop amount as expected except for wetland bird abundance. In contrast, greater crop heterogeneity actually strengthened the negative effects of high crop amount on forest bird abundance, shrub-forest edge bird diversity and total bird diversity. We speculate that this was due to negative correlations between crop heterogeneity and the amount of shrub and forest habitat patches in crop-dominated landscapes in our study region. The variable response to crop heterogeneity across guilds suggests that policies aimed at crop diversification may not enhance avian diversity on their own and that management efforts aimed at the retention of natural forest and shrub patches, riparian corridors, and hedge-rows would be more directly beneficial.     

Distribution of N,P, K,Ca, Mg,S, Zn,Fe, Mn and Cu in groundnut

Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons.