• Authors:
    • Oyerinde, A.
    • Chuwang, P.
    • Oyerinde, G.
  • Source: The Journal of Plant Protection Sciences
  • Volume: 5
  • Issue: 1
  • Year: 2013
  • Summary: Insect response to rise in atmospheric temperature and carbon dioxide differ from one region to the other. The latest assessment report from the Intergovernmental Panel on Climate Change (IPCC) predicts an increment in mean atmospheric temperature from 1.1 to 6.4°C toward the year 2100 with equally increasing atmospheric carbon dioxide (CO 2). Such climatic changes could profoundly affect insect's population on essential crops. This study was conducted during the 2010 and 2011 cropping season at the University of Abuja Teaching and Research Farm (Nigeria) in order to determine the impacts of climate change on the population of insects associated with cowpea production in the region. The result showed an increase in the number of taxa encountered on the cowpea field from 21 to 31 orders of insect in the 2010 and 2011 cropping seasons, respectively. Also, no significant difference was established in the forms of destructions recorded at the various growth stages of the cowpea plant in the two seasons. Therefore the advent of increased fauna on cowpea established in this study portrayed a need to find possible ways to reduce the emission of Greenhouse gases in the region in order to ameliorate the effects of induced global warming on cowpea production in the country and also provide effective control of the identified pest in order to maintain or stall resurgence.
  • Authors:
    • Rotz, C. A.
    • Mauzerall, D. L.
    • Kanter, D.
    • Gehl, R. J.
    • Bruulsema, T. W.
    • Robertson, G. P.
    • Williams, C. O.
  • Source: Biogeochemistry
  • Volume: 114
  • Issue: 1-3
  • Year: 2013
  • Summary: Agriculture in the United States (US) cycles large quantities of nitrogen (N) to produce food, fuel, and fiber and is a major source of excess reactive nitrogen (Nr) in the environment. Nitrogen lost from cropping systems and animal operations moves to waterways, groundwater, and the atmosphere. Changes in climate and climate variability may further affect the ability of agricultural systems to conserve N. The N that escapes affects climate directly through the emissions of nitrous oxide (N2O), and indirectly through the loss of nitrate (NO3 (-)), nitrogen oxides (NO (x) ) and ammonia to downstream and downwind ecosystems that then emit some of the N received as N2O and NO (x) . Emissions of NO (x) lead to the formation of tropospheric ozone, a greenhouse gas that can also harm crops directly. There are many opportunities to mitigate the impact of agricultural N on climate and the impact of climate on agricultural N. Some are available today; many need further research; and all await effective incentives to become adopted. Research needs can be grouped into four major categories: (1) an improved understanding of agricultural N cycle responses to changing climate; (2) a systems-level understanding of important crop and animal systems sufficient to identify key interactions and feedbacks; (3) the further development and testing of quantitative models capable of predicting N-climate interactions with confidence across a wide variety of crop-soil-climate combinations; and (4) socioecological research to better understand the incentives necessary to achieve meaningful deployment of realistic solutions.
  • Authors:
    • Didik, I.
    • Purwanto, B. H.
    • Wijanarko, A.
    • Dja'far, S.
  • Source: Journal of Agricultural and Biological Science
  • Volume: 8
  • Issue: 11
  • Year: 2013
  • Summary: This research aims to study the kinetics of N mineralization by using double-pool kinetics models on degradated soils in the cultivation of monoculture cassava as a result of providing organic matter of legume and non-legume. Incubation experiments were conducted in the laboratory at a constant temperature. The treatment was by giving nonlegume and legume biomass on Ultisol in which cassava has been planted there with different lengths of time. In this research, to estimate the parameters of the mineralized N and the rate of mineralization (k), double-pool kinetics equation was used. Mean while, the relationship between the parameters of N mineralization with nutrient uptake was investigated by conducting a pot experiment in a greenhouse. The results showed that the application of organic matter derived from groundnut produced higher mineralization. The N mineralization of soil that has been planted by cassava less than ten years was higher than it was on soil that has been planted by cassava more than 30 years. The total amount of N released on soil that has been planted by cassava less than 10 years reached 1086 mg kg -1. Whereas, the total amount of N released on soil already planted with cassava more than 30 years was 783 mg kg -1. Potential value of N (N0) and the mineralization rate coefficient (k) were higher in organic matter with a low ratio of C:N and on more fertile soil.
  • Authors:
    • Cui, S.
    • Chang, X.
    • Xu, B.
    • Zhu, X.
    • Luo, C.
    • Wang, S.
    • Duan, J.
    • Zhang, Z.
  • Source: Plant and Soil
  • Volume: 362
  • Issue: 1-2
  • Year: 2013
  • Summary: Few studies have investigated the effect of nitrogen (N) fertilizer on ecosystem respiration (Re) under mixed legume and grass pastures sown at different seeding ratios,and data are almost entirely lacking for alpine meadow of the Tibetan Plateau. Our aim was to test the hypothesis that although a combination of legumes with grass and N fertilizer increases Re the combination decreases Re intensity (i.e. Re per unit of aboveground biomass) due to greater increases in aboveground biomass compared to increases in Re. This hypothesis was tested using different seeding ratios of common vetch (Vicia sativa L.) and oat (Avena sativa L.) with and without N fertilizer on the Tibetan plateau in 2009 and 2010. Re was measured using a static closed opaque chamber. Re intensity was estimated as the ratio of seasonal average Re during the growing season to aboveground biomass. Compared with common vetch monoculture pasture, mixed legume-grass pastures only significantly decreased Re intensity (with a decrease of about 75 %-87 %) in the drought year 2009 due to greater increases in aboveground biomass compared to increases in Re. There were no significant differences in Re and Re intensity among different seeding ratios of oat and common vetch in either year. N fertilizer significantly decreased Re intensity for common vetch monoculture pasture by 24.5 % in 2009 and 69.5 % in 2010 although it did not significantly affect plant production and Re. From the perspective of forage yield and Re, planting mixed legume-grass pastures without N fertilizer is a preferable way to balance the twin objectives of forage production and mitigation of atmospheric greenhouse gas emissions in alpine regions.
  • Authors:
    • Nyiraneza, J.
    • Gagnon, B.
    • Ziadi, N.
  • Source: Canadian Journal of Soil Science
  • Volume: 93
  • Issue: 3
  • Year: 2013
  • Summary: Les biosolides papetiers (BP) en combinaison avec les residus industriels alcalins pourraient beneficier aux sols agricoles tout en les detournant des sites d'enfouissement. Une etude en serre a ete menee afin d'evaluer l'effet de trois types de BP a des taux de 0,30, et 60 Mg humide ha(-1), ainsi que cinq sous-produits chaulants a 3 Mg humide ha(-1) avec 30 Mg BP ha(-1) stir le rendement des cultures, l'accumulation des elements nutritifs et les proprietes du sol. Des biosolides de desencrage (BD, C/N de 65) ont ete appliques au soya [Glycine max (L.) Merr.], et deux BP mixtes (BPI, C/N de 31; et BP2, C/N de 14) ont ete appliqu s a du haricot sec (Phaseolus vulgaris L.) et de l'orge (Hordettm vulgare L.), respectivement. Les sous-produits chaulants incluaient des boues de chaux (BC), des cendres de bois de papetieres, de la chaux calcique commerciale (CC), des sous-produits de dissolution magnesien, et des residus de Mg provenant du travail de la fonte et d'electrolyse (MgFE). Par rapport au temoin, BP2 a augment& le rendement de l'orge et l'accumulation totale en Mg et Na, et les deux BP ont augmente l'accumulation du N, P et Ca dans les plants d'orge et de haricot. L'impact des BD sur le soya a ete limite. L'ajout de sous-produits chaulants a BD ou BP n'a pas eu d'incidence sur les parametres culturaux a l'exception de la combinaison avec MgFE qui a fortement reduit la croissance du haricot sec et, dans une moindre mesure, le soya. Le NO3-N du sol a ete immobilise suite a l'application de BD alors qu'il y a eu un relachement net avec les deux BP. La combinaison BP et sous-produits chaulants a produit les plus grands changements dans les proprietes du sol a la recolte. En regle generale, BC et CC ont augmente le pH et le Ca extrait au Mehlich-3, et MgFE a cause une forte augmentation du Mehlich-3 Mg et Na et du Cl soluble a l'eau. Lorsqu'ils sont utilises avec des cultures appropriees, les biosolides de papetieres et les residus alcalins autres que MgFE peuvent ameliorer efficacement la fertilite des sols en fournissant du C organique et des elements nutritifs majeurs pour equilibrer la fertilisation des cultures.
  • Authors:
    • Petersen,Soren O.
    • Schjonning,Per
    • Olesen,Jorgen E.
    • Christensen,Soren
    • Christensen,Bent T.
  • Source: Soil Science Society of America Journal
  • Volume: 77
  • Issue: 1
  • Year: 2013
  • Summary: In organic cropping systems, legumes, cover crops (CC), residue incorporation, and manure application are used to maintain soil fertility, but the contributions of these management practices to soil nitrogen (N) supply remain obscure. We examined potential sources of N for winter wheat (Triticum aestivum L.) in four experimental cropping systems established in 1997 on three soil types. Three of the four systems were under organic management. Topsoil N, depth of the A horizon, and cumulated inputs of N since 1997 were determined at plot level. Labile soil N pools [mineral N, potentially mineralizable N (PMN), microbial biomass N (MBN)] were monitored during two growth periods; at one site, biomass C/N ratios were also determined. Soil for labile N analysis was shielded from N inputs during spring application to isolate cumulated system effects. Potentially mineralizable N and MBN were correlated across all sites and rotations (r(2) = 0.72). The MBN corresponded to 46 to 85, 85 to 145, and 74 to 172 kg N ha(-1) at the three sites and differed significantly between cropping systems, but MBN could not explain differences in wheat grain N yields. Instead, a multiple linear regression model explained 76 and 82% of the variation in grain N yields in organic cropping systems in 2007 and 2008, showing significant effects of, respectively, topsoil N, depth of A horizon, cumulated inputs of N, and N applied to winter wheat in manure. Thus, soil properties and past and current management all contributed to winter wheat N supply.
  • Authors:
    • Jamont,Marie
    • Piva,Guillaume
    • Fustec,Joelle
  • Source: Plant and Soil
  • Volume: 371
  • Issue: 1-2
  • Year: 2013
  • Summary: Legume-brassica intercrops may help to reduce N fertilizer input. We tested whether (i) intercropping with faba bean can improve N status of rapeseed, and (ii) root complementarity and/or N transfer is involved in such performance. Pre-germinated rapeseed and faba bean were grown either together or in monospecific rhizotrons (2 plants per rhizotron). Root growth was recorded. N rhizodeposition of the crops and N transferred between species were assessed using a N-15 stem-labelling method. Intercropped rapeseeds accumulated 20 % higher amounts of N per plant than monocultures. Up to 32 days after sowing, root distribution in the rhizotrons was favourable to physical sharing of the soil N: 64 % of faba bean root length was located in the upper part, as 70 % was in the lower part for rapeseed. At late flowering of the faba bean (52 days after sowing), N rhizodeposition of the two crops were similar and reached 8 to 9 % of the plant N. N transferred from the faba bean to the rapeseed was similar to that transferred from the rapeseed to the faba bean. Niche complementarity benefits more intercropped rapeseed than net N fluxes between species in the early growth.
  • Authors:
    • Lemke, R. L.
    • Vandenbygaart, A. J.
    • Campbell, C. A.
    • Lafond, G. P.
    • McConkey, B. G.
    • Grant, B.
  • Source: Canadian Journal of Soil Science
  • Volume: 92
  • Issue: 3
  • Year: 2012
  • Summary: Carbon sequestration in soil is important due to its influence on soil fertility and its impact on the greenhouse gas (GHG) phenomenon. Carbon sequestration is influenced by agronomic factors, but to what extent is still being studied. Long-term agronomic studies provide one of the best means of making such assessments. In this paper we discuss and quantify the effect of cropping frequency, fertilization, legume green manure (LGM) and hay crops in rotations, and tillage on soil organic carbon (SOC) changes in a thin Black Chernozemic fine-textured soil in southeastern Saskatchewan. This was based on a 50-yr (1958-2007) crop rotation experiment which was initiated on land that had previously been in fallow-wheat ( Triticum aestivum L.) (F-W), or F-W-W receiving minimum fertilizer for the previous 50 yr. We sampled soil in 1987, 1996 (6 yr after changing from conventional tillage to no-tillage management and increasing N rates markedly) and again in 2007. The SOC (0-15 cm depth) in unfertilized F-W and F-W-W appears not to have changed from the assumed starting level, even after 20 yr of no-till, but SOC in unfertilized continuous wheat (Cont W) increased slightly [not significant ( P>0.05)] in 30 yr, but increased more after 20 yr of no-till (but still not significant). No-till plus proper fertilization for 20 yr increased the SOC of F-W, F-W-W and Cont W in direct proportion to cropping frequency. The SOC in the LGM-W-W (unfertilized) system was higher than unfertilized F-W-W in 1987, but 20 yr of no-tillage had no effect, likely because grain yields and C inputs were depressed by inadequate available P. Soil organic carbon in the two aggrading systems [Cont W (N+P) and F-W-W-hay(H)-H-H (unfertilized)] increased significantly ( P<0.05) in the first 30 yr; however, a further 20 yr of no-tillage (and increased N in the case of the Cont W) did not increase SOC suggesting that the SOC had reached a steady-state for this soil and management system. The Campbell model effectively simulated SOC changes except for Cont W(N+P), which it overestimated because the model is ineffective in simulating SOC in very fertile systems. After 50 yr, efficiency of conversion of residue C inputs to SOC was negligible for unfertilized F-W and F-W-W, was 3 to 4% for fertilized fallow-containing systems, was about 6 or 7% for Cont W, and about 11% for the unfertilized F-W-W-H-H-H systems.
  • Authors:
    • Martins, M. dos R.
    • Angers, D. A.
    • Cora, J. E.
  • Source: Soil Science Society of America Journal
  • Volume: 76
  • Issue: 2
  • Year: 2012
  • Summary: In no-till systems, plants play a substantial role in soil physical conditioning because physical management is otherwise confined to sowing operations. We performed a study to determine the effect of 28 different crop sequences on soil water-stable aggregation, soil organic C (SOC), and the neutral carbohydrate composition of the surface layer (0-5-cm depth) of an Oxisol under no-till. Summer crop sequences with corn ( Zea mays L.) on a continuous basis or in rotation with soybean [ Glycine max (L.) Merr.] showed a higher mean weight diameter (MWD) of water-stable aggregates than those with a rice ( Oryza sativa L.)-bean ( Phaseolus vulgaris L.)-cotton ( Gossypium hirsutum L.) rotation. Among winter crops, pearl millet [ Pennisetum americanum (L.) Leeke] or grain sorghum [ Sorghum bicolor (L.) Moench] were associated with a higher MWD than oilseed radish ( Raphanus sativus L. var. oleiformis Pers.). Plant tissues of Poaceae species (corn, pearl millet, and sorghum) were enriched in pentoses relative to other plant species. A principal component analysis showed a close positive relationship of the soil aggregate MWD with the soil xylose content, but not with other soil monosaccharide and SOC contents, and a positive relationship with the amount of pentose input to the soil, notably from aboveground plant materials. A possible explanation is that pentosans are used as an energy source by filamentous microorganisms, which play a well-known role in stabilizing soil aggregates. Our results suggest that plant-derived carbohydrates mediate crop species effects on soil structure under no-till conditions, and this effect appears to be independent of changes in total SOC.
  • Authors:
    • Seufert, V.
    • Ramankutty, N.
    • Foley, J. A.
  • Source: Nature
  • Volume: 485
  • Issue: 7397
  • Year: 2012
  • Summary: Numerous reports have emphasized the need for major changes in the global food system: agriculture must meet the twin challenge of feeding a growing population, with rising demand for meat and high-calorie diets, while simultaneously minimizing its global environmental impacts. Organic farming - a system aimed at producing food with minimal harm to ecosystems, animals or humans - is often proposed as a solution. However, critics argue that organic agriculture may have lower yields and would therefore need more land to produce the same amount of food as conventional farms, resulting in more widespread deforestation and biodiversity loss, and thus undermining the environmental benefits of organic practices. Here we use a comprehensive meta-analysis to examine the relative yield performance of organic and conventional farming systems globally. Our analysis of available data shows that, overall, organic yields are typically lower than conventional yields. But these yield differences are highly contextual, depending on system and site characteristics, and range from 5% lower organic yields (rain-fed legumes and perennials on weak-acidic to weak-alkaline soils), 13% lower yields (when best organic practices are used), to 34% lower yields (when the conventional and organic systems are most comparable). Under certain conditions - that is, with good management practices, particular crop types and growing conditions - organic systems can thus nearly match conventional yields, whereas under others it at present cannot. To establish organic agriculture as an important tool in sustainable food production, the factors limiting organic yields need to be more fully understood, alongside assessments of the many social, environmental and economic benefits of organic farming systems.