Pasture Rotation Research Articles

Composition of late summer diet by semi-domesticated reindeer in different grazing conditions in northernmost Finland

This study aims to investigate the diet composition of semi-domesticated reindeer (Rangifer tarandus tarandus) in late summer in different kinds of grazing conditions in northernmost Finland. The composition of diet by reindeer was determined on the grounds of microhistological analysis of feces samples collected in early August in different seasonal grazing areas (winter or summer/year-round grazing areas) in three reindeer management districts. Although the proportion of different plant groups varied between the studied districts, the quantified group of ground lichens (which also contained small amounts of mushrooms) was the most abundant, varying from 33.0 to 46.4% in the analyzed samples. In general, there were significant differences in the proportions of lichen between districts, but not between grazing areas. The proportion of lichen in samples increased significantly when the amount of lichen pasture around a sample site increased. The proportion of dwarf shrubs and leaves in samples varied from 24.9 to 37.9% and differed significantly between districts, but not between grazing areas. In the same way, the proportion of graminoids varied between 20.9 and 36.2% and differed significantly between districts and also between grazing areas. Higher amounts of graminoids in feces were observed in summer/year-round grazing areas than in winter grazing areas. Finally, the proportion of bryophytes varied between 2.9 and 6.5% and was significantly different between districts, but not between grazing areas. An increase in old and mature coniferous forest around a sample site significantly increased the amounts of bryophytes in samples. The results indicate that reindeer adapt their summer diet composition according to the availability of food plants. The results also show that when reindeer are allowed to select their summer ranges freely, reindeer tend to use lichen pastures intensively also during summer, which causes a considerable reduction in lichens due to grazing and trampling. Therefore, a proper seasonal pasture rotation system to protect lichen pastures from grazing and trampling, from early spring to late autumn, is an essential part of sustainable pasture use in reindeer herding.

Land use and land cover in critical source areas on small dairy farms in the eastern United States

Rotational grazing (RG) is a livestock management practice that moves grazing cattle among small temporary pastures called paddocks. In dairy farming, RG has potential to improve soil and water conservation by situating well-managed perennial vegetation on erosion-prone parts of farm landscapes. Recently, geospatial technologies have enabled precise identification of “critical source areas” (CSAs). CSAs are sites where slope, soil, and water flow factors coincide to create the largest potential impacts on surface water quality from erosion within the landscape of a farm. Examination of land-use and land-cover (LULC) practices on CSAs allows nuanced comparisons of effects on water resources among agricultural production systems, enabling us to test the hypothesis that RG dairy farms manage CSAs so as to have lesser effects on water resources than comparable-sized nongrazing dairy farms. We assessed LULC on CSAs in 53 small dairy farms in New York, Pennsylvania, and Wisconsin, United States, using satellite imagery and other spatial data. Among these farms, 22 used some form of RG, while the remainder did not use grazing. We also did on-farm observations of most CSAs to assess the frequency of features that may particularly affect water resources, such as unvegetated areas within pastures. RG dairy farms differed significantly from nongrazing dairy farms in the total allocation of CSA area to hayfields and rotational pastures—two LULC types that are likely to reduce runoff and emissions of sediment and nutrients into waterways—but this difference varied across the states and was pronounced only in the Pennsylvania farms, where high-intensity grazing farms allocated these perennial LULC types to over 60% of CSA lands, while nongrazing farms allocated these LULC types to about 20% of CSAs. In New York and Pennsylvania, RG farms allocated significantly less erosion-prone annual cropland to CSA sites than nongrazing farms, and allocated less of the total farm area to LULC practices that are relatively vulnerable to soil erosion. However, these differences between farm types were pronounced only in Pennsylvania farms. Our results do not support the hypothesis that RG dairy farms are generally superior to comparably sized nongrazing dairy farms in their management of CSAs. It is likely that targeted technical and cost-share support could improve management of CSAs in RG farms, allowing them to more fully realize the potential of RG systems to improve soil and water conservation.

Reindeer management and winter pastures in the presence of supplementary feeding and government subsidies

We apply an age- and sex-structured reindeer-lichen model to examine the role of winter pastures, pasture rotation, and supplementary feeding on economically optimal reindeer management. The model includes 17 age classes of females, 13 classes of males and a detailed description of winter energy resource utilization by the reindeer population. Reproduction is specified by a modified harmonic mean mating system and the diet choice between different winter energy resources follows the principles of the optimal foraging theory. Wintertime energy intake defines an individual's weight decrease and its consequences on mortality and reproduction. Lichen growth depends on habitat type and lichen biomass. The decision variables are the animals chosen for slaughter from each age and sex class and the amount of supplementary food given. Results show that the availability of arboreal lichens, the growth rate of ground lichens, and pasture rotation all determine the optimal solutions. Reindeer management aiming to maximize long-term net economic revenues leads to very low lichen densities if intensive feeding becomes optimal in the long-term steady state. Government subsidies promote reindeer herders to base management on supplementary feeding leading to lower pasture conditions and to the depletion of lichens.

Impact of Location, Cropping History, Tillage, and Chlorpyrifos on Soil Arthropods in Peanut.

Demand for agricultural production systems that are both economically viable and environmentally conscious continues to increase. In recent years, reduced tillage systems, and grass and pasture rotations have been investigated to help maintain or improve soil quality, increase crop yield, and decrease labor requirements for production. However, documentation of the effects of reduced tillage, fescue rotation systems as well as other management practices, including pesticides, on pest damage and soil arthropod activity in peanut production for the Mid-Atlantic US region is still limited. Therefore, this project was implemented to assess impacts of fescue-based rotation systems on pests and other soil organisms when compared with cash crop rotation systems over four locations in eastern North Carolina. In addition, the effects of tillage (strip vs. conventional) and soil chlorpyrifos application on pod damage and soil-dwelling organisms were also evaluated. Soil arthropod populations were assessed by deploying pitfall traps containing 50% ethanol in each of the sampled plots. Results from the present study provide evidence that location significantly impacts pest damage and soil arthropod diversity in peanut fields. Cropping history also influenced arthropod diversity, with higher diversity in fescue compared with cash crop fields. Corn rootworm damage to pods was higher at one of our locations (Rocky Mount) compared with all others. Cropping history (fescue vs. cash crop) did not have an effect on rootworm damage, but increased numbers of hymenopterans, acarina, heteropterans, and collembolans in fescue compared with cash crop fields. Interestingly, there was an overall tendency for higher number of soil arthropods in traps placed in chlorpyrifos-treated plots compared with nontreated controls.

Sámi reindeer herders' perspective on herbivory of subarctic mountain birch forests by geometrid moths and reindeer: a case study from northernmost Finland.

IntroductionGeometrid moths and semi-domesticated reindeer are both herbivores which feed on birch leaves in the subarctic mountain birch forests in northern Fennoscandia. The caterpillars of autumnal and winter moths have episodic outbreaks, which can occasionally lead to extensive defoliation of birch forests. Earlier studies have shown that reindeer have a negative effect on the regeneration of defoliated birches by grazing and browsing their seedlings and sprouts.Case descriptionWe interviewed 15 reindeer herders in the Kaldoaivi and Paistunturi herding co-operative in northernmost Finland in order to analyse their past, present and future views on the behaviour of moths and the growth of mountain birches. We investigate the behaviour of the two herbivores by combining the indigenous knowledge (IK) of Sámi herders with the results of relevant studies in biology and anthropology, applying niche construction theory (NCT) in doing so.Discussion and evaluationIn the first stage, the niche constructors (moths, reindeer, herders, mountain birch and other organisms) are looked upon as “equal constructors” of a shared niche. As changes unfold in their niche, their role changes from that of constructor to key constructor. The role and importance of niche constructors were different when nomadic pasture rotation was used than they are today under the herding co-operative system. Niche construction faced its most radical and permanent negative changes during the border closures that took place over the latter half of the 19th century. The large-scale nomadic life among the Sámi herders, who migrated between Finland and Norway, came to an end. This phase was followed by stationary herding, which diminished the possibilities of reindeer to look for various environmental affordances. Difficult snow conditions or birch defoliation caused by moth outbreaks made the situation worse than before. Eventually reindeer became key constructors, together with moth larvae, leading to negative ecological inheritance that forced herders to use new, adaptive herding practices.ConclusionsBoth the scientific data and the IK of herders highlight the roles of reindeer and herders as continuous key constructors of the focal niche, one which stands to be modified in more heterogenic ways than earlier due to global warming and hence will result in new ecological inheritance.

Modelling Pasture-based Automatic Milking System Herds: The Impact of Large Herd on Milk Yield and Economics.

The aim of this modelling study was to investigate the effect of large herd size (and land areas) on walking distances and milking interval (MI), and their impact on milk yield and economic penalties when 50% of the total diets were provided from home grown feed either as pasture or grazeable complementary forage rotation (CFR) in an automatic milking system (AMS). Twelve scenarios consisting of 3 AMS herds (400, 600, 800 cows), 2 levels of pasture utilisation (current AMS utilisation of 15.0 t dry matter [DM]/ha, termed as ‘moderate’; optimum pasture utilisation of 19.7 t DM/ha, termed as ‘high’) and 2 rates of incorporation of grazeable complementary forage system (CFS: 0, 30%; CFS = 65% farm is CFR and 35% of farm is pasture) were investigated. Walking distances, energy loss due to walking, MI, reduction in milk yield and income loss were calculated for each treatment based on information available in the literature. With moderate pasture utilisation and 0% CFR, increasing the herd size from 400 to 800 cows resulted in an increase in total walking distances between the parlour and the paddock from 3.5 to 6.3 km. Consequently, MI increased from 15.2 to 16.4 h with increased herd size from 400 to 800 cows. High pasture utilisation (allowing for an increased stocking density) reduced the total walking distances up to 1 km, thus reduced the MI by up to 0.5 h compared to the moderate pasture, 800 cow herd combination. The high pasture utilisation combined with 30% of the farm in CFR in the farm reduced the total walking distances by up to 1.7 km and MI by up to 0.8 h compared to the moderate pasture and 800 cow herd combination. For moderate pasture utilisation, increasing the herd size from 400 to 800 cows resulted in more dramatic milk yield penalty as yield increasing from c.f. 2.6 and 5.1 kg/cow/d respectively, which incurred a loss of up to $AU 1.9/cow/d. Milk yield losses of 0.61 kg and 0.25 kg for every km increase in total walking distance (voluntary return trip from parlour to paddock) and every one hour increase in MI, respectively. The high pasture utilisation combined with 30% of the farm in CFR in the farm increased milk yield by up to 1.5 kg/cow/d, thereby reducing loss by up to $0.5/cow/d (c.f. the moderate pasture and 800 cow herd scenario). Thus, it was concluded that the successful integration of grazeable CFS with pasture has the potential to improve financial performance compared to the pasture only, large herd, AMS.

Desempenho produtivo e econômico de três grupos genéticos de bovinos recriados a pasto com suplementação e terminados em confinamento

Avaliou-se o desempenho produtivo e econômico de três grupos genéticos de bovinos em sistema com recria a pasto e terminação em confinamento, com ciclo de produção de um ano. Foram utilizados 36 bovinos não castrados, com média de 270±50 dias de idade e peso médio inicial de 241,3±34kg, sendo 12 Guzolandos (1/2 Guzerá x 1/2 Holandês), 12 Guzonel (1/2 Guzerá x 1/2 Nelore) e 12 Tricross (1/2 Simental x 1/2 Guzonel). O delineamento estatístico foi inteiramente ao acaso. Os animais permaneceram em pastejo rotacionado de Brachiaria brizantha cv. Marandu, com suplementação comercial; na terminação, receberam dieta composta por silagem de sorgo e concentrado (50:50) durante 61 dias. Os índices de desempenho avaliados foram o ganho médio de peso diário (GMD), ganho médio de peso no período, peso corporal final e, como indicadores econômicos, a receita total, custo operacional total por arroba (COT/@), margem bruta e margem líquida. O GMD na recria foi semelhante (P>0,05) entre os grupos que apresentaram média de 746 e 456 gramas, respectivamente, para os períodos águas/transição águas-seca e seca. O COT/@ da recria do grupo Tricross (R$69,44) foi superior aos dos grupos Guzonel (R$66,75) e Guzolando (R$ 64,86). No período de terminação, o GMD foi semelhante entre os grupamentos, apresentanto o valor médio de 1,55kg. O COT/@ da terminação em confinamento foi R$ 91,48, R$114,15 e R$122,78, para Tricross, Guzonel e Guzolando, respectivamente. Considerando-se o sistema de ciclo curto completo, obteve-se COT/@ menor para o grupamento Tricross (R$77,92), seguido pelo grupamento Guzonel (R$ 74,89) e Guzolando (R$ 78,43). Nas condições de produção avaliadas, o grupo Tricross foi o mais eficiente economicamente.

Considering long-term ecological effects on future land-use options when making tactical break-crop decisions in cropping systems

In cropping systems where one type of crop dominates for economic reasons, farmers may employ alternative cropping or pasture options for strategic purposes such as controlling weed populations, reducing crop disease, and accumulating soil nitrogen. Tactical decisions regarding break crops often involve understanding the economic implications of several interacting bio-physical factors, along with complex trade-offs between short-term benefits, such as immediate profit, and long-term ecological problems, such as increased weed seedbank. Modelling analysis regarding tactical crop-sequencing and break-crop decisions has generally not addressed these longer term dynamic factors. In this study we adapted an analysis and modelling framework (LUSO), originally designed to aid understanding of the long-term strategic planning of agricultural crop and pasture rotations, so that it can be used to analyse immediate tactical decisions regarding break crops and sequencing, while still accounting for both short- and long-term implications of these decisions. We show how the revised framework was applied to two example scenarios and demonstrate that in both cases it can be used for simple decision-support, as well as more in-depth analysis and insight into the factors influencing the immediate decision.

Seasonal nitrous oxide and methane fluxes from grain- and forage-based production systems in wisconsin, USA.

Agriculture in the midwestern United States is a major anthropogenic source of nitrous oxide (NO) and is both a source and sink for methane (CH), but the degree to which cropping systems differ in emissions of these gases is not well understood. Our objectives were to determine if fluxes of NO and CH varied among cropping systems and among crop phases within a cropping system. We compare NO and CH fluxes over the 2010 and 2011 growing seasons from the six cropping systems at the Wisconsin Integrated Cropping Systems Trial (WICST), a 20-yr-old cropping systems experiment. The study is composed of three grain and three forage cropping systems spanning a spectrum of crop diversity and perenniality that model a wide range of realistic cropping systems that differ in management, crop rotation, and fertilizer regimes. Among the grain systems, cumulative growing season NO emissions were greater for continuous corn ( L.) (3.7 kg NO-N ha) than corn-soybean [ (L.) Merr.] (2.0 kg NO-N ha) or organic corn-soybean-wheat ( L.) (1.7 kg NO-N ha). Among the forage systems, cumulative growing-season NO emissions were greater for organic corn-alfalfa ( L.)-alfalfa (2.9 kg NO-N ha) and conventional corn-alfalfa-alfalfa-alfalfa (2.5 kg NO-N ha), and lower for rotational pasture (1.9 kg NO-N ha). Application of mineral or organic N fertilizer was associated with elevated NO emissions. Yield-scaled emissions (kg NO-N Mg) did not differ by cropping system. Methane fluxes were highly variable and no effect of cropping system was observed. These results suggest that extended and diversified cropping systems could reduce area-scaled NO emissions from agriculture, but none of the systems studied significantly reduced yield-scaled NO emissions.

Past and Present Winter Feeding of Reindeer in Finland: Herders’ Adaptive Learning of Feeding Practices

The research examines reindeer feeding practices and herders’ learning of them in three herding co-operatives in Finland: Kuukas in the south, Oraniemi in the central area, and Hammastunturi in the north. In the southern and central co-operatives, from the late 19th century until the Second World War (1939 – 45), trees rich in lichens were cut to provide emergency forage. Harvesting lichens from trees and feeding associated with “tether calving” and “fence calving” have been common in the central and northern co-operatives. In the 1960s and 1970s, poor digging conditions resulted in reindeer losses, and pressure to feed reindeer increased further as forestry practices and overgrazing caused pastures to decline. Large-scale feeding entered daily practice in Kuukas and Oraniemi in the late 1980s and mid-1990s. The increased interaction between humans and reindeer brought about by regular feeding has made the animals tamer. In fact, they have adopted the permanent feeding areas as part of their pasture rotation. In Hammastunturi, herders entice reindeer from one pasture to another by providing supplementary forage. Knowledge about feeding developed in close concert with agriculture, and was transferred from south to north in the1980s and 1990s. We argue that feeding practices draw on traditional ecological knowledge, which includes old ways of herding cattle. Herders’ personal working practices and training are knowledge that is difficult to describe in words and must be learned by experience. Learning to feed reindeer requires not only familiarity with herding in practice (which implies profound knowledge about the animals, their nutrition, digestion, behavior, and handling), but also familiarity with the herding district and co-operation across generations.

Characterization of Soil Organic Matter in Aggregates and Size-Density Fractions by Solid State 13C CPMAS NMR Spectroscopy

Understanding the changes in soil organic matter (SOM) composition during aggregate formation is crucial to explain the stabilization of SOM in aggregates. The objectives of this study were to investigate (i) the composition of SOM associated with different aggregates and size-density fractions and (ii) the role of selective preservation in determining the composition of organic matter in aggregate and size-density fractions. Surface soil samples were collected from an Alfisol on the Northern Tablelands of NSW, Australia, with contrasting land uses of native pasture, crop–pasture rotation and woodland. Solid-state 13C cross-polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy was used to determine the SOM composition in macroaggregates (250–2000 μm), microaggregates (53–250 μm), and <53-μm fraction. The chemical composition of light fraction (LF), coarse particulate organic matter (cPOM), fine particulate organic matter (fPOM), and mineral-associated soil organic matter (mSOM) were also determined. The major constituent of SOM of aggregate size fractions was O-alkyl carbon, which represented 44–57% of the total signal acquired, whereas alkyl carbon contributed 16–27%. There was a progressive increase in alkyl carbon content with decrease in aggregate size. Results suggest that SOM associated with the <53-μm fraction was at a more advanced stage of decomposition than that of macroaggregates and microaggregates. The LF and cPOM were dominated by O-alkyl carbon while alkyl carbon content was high in fPOM and mSOM. Interestingly, the relative change in O-alkyl, alkyl, and aromatic carbon between aggregates and SOM fractions revealed that microbial synthesis and decomposition of organic matter along with selective preservation of alkyl and aromatic carbon play significant roles in determining the composition of organic matter in aggregates.

A study of cattle producer preferences for best management practices in an East Tennessee watershed

Best Management Practices (BMPs) contribute to a broader range of efforts to improve the environmental performance of the livestock sector and its impact on water quality. This research evaluates a survey of cattle producers in an East Tennessee watershed and parts of five surrounding watersheds, along with and the factors correlated with preferences for BMPs designed to reduce sediment, nutrient, and fecal coliform contamination of surface waters by limiting cattle access to streams. The objective of the survey was to gather behavioral information about producer interest in specific BMPs in an effort to supplement a long-term biophysical modeling project. Structures and BMPs analyzed include stream crossings, rotational grazing, pasture improvement, and cattle water tanks. The physical and economic constraints faced by producers and the incentives provided by state and federal programs influence the decision to adopt a set of practices or structures that impact pathogen loading into streams. There was a clear preference for a suite of BMPs that did not include stream crossings, reinforcing anecdotal evidence that the maintenance associated with frequent high flow events may reduce willingness to install stream crossings. Cattle producers were more willing to implement rotational grazing and pasture improvement BMPs, which were associated with cattle health and productivity. The extensive distribution of pastureland in the region analyzed, the relatively inexpensive costs of adopting practices supporting pasture improvement, and higher quality forage correlated with improved pastures suggest a win-win outcome for cattle owners and efforts to enhance water quality.

Soil carbon indices as affected by 10 years of integrated crop–livestock production with different pasture grazing intensities in Southern Brazil

Brazil has the world's second-largest cattle herd and second-largest no-till grain crop area. However, these activities are not frequently integrated because there is a widespread perception that cattle have a negative effect on cropping, especially when high crop yields are a goal. This misunderstanding of the synergy between pastures, livestock and crops is linked to overgrazing at the pasture rotation phase, which causes a decline in soil quality. Few studies have investigated the effect of pasture grazing intensities on soil carbon (C) balance and soil quality in subtropical environments. This work assessed the effects of different grazing intensities (0.10, 0.20, 0.30 and 0.40m sward height) on soil C indices and animal productivity in a clay Haplorthox. The crop–livestock system model was a soybean/ryegrass plus black oat annual rotation managed for 10 years, using a randomized complete block design with three replications. Grazing intensity affected the quantity and composition of soil C input. Under heavy grazing with limited soil C input, there was a decrease in pasture and an increase in soybean participation in total C input. Soil organic C (0–0.20m) under different grazing intensities had a linear relationship with C stratification ratio, C management index (CMI) and C pool index. Our results suggest that integrated crop–livestock systems could act as atmospheric C sources or sinks, depending on the grazing intensity. Pastures managed at 0.20 and 0.40m height had the best balance between CMI and animal daily gain. The best balance between CMI and live weight gain per unit area occurred in sward height of 0.20m.

Transition to self-sufficient mixed crop–dairy farming systems

AbstractWhile plains favorable to agriculture are still dominated by specialized and intensive agriculture, self-sufficient mixed crop-dairy farming systems increasingly attract policy makers' and scientists' attention. Owing to their limited use of purchased inputs, they can contribute to reducing the environmental impact of agriculture. Furthermore, self-sufficient farming tends to be linked with a search for autonomy in decision-making, i.e., farmers developing their own technical reference framework. Such farming systems can thus also contribute to alternative development pathways of rural territories. In this paper, we analyze how ten intensive mixed crop–dairy farms have progressively evolved toward more self-sufficient and autonomous systems. Through formalizing farmers' transitionin action, we identified 34 tools that the farmers implemented making them reflect on their farming system, shift socio-professional networks, reorganize work routines, and steer the evolution of their production practices. For example, they created temporary pastures in crop rotation, introduced rotational pastures, observed their herds to adjust their feed and keep the animals in good health, and they limited expenditures to manage their cash flow. Which tools were used and when they were used depends on what is meaningful to them at various stages of the transition. Our analysis of transitionsin actionhas three original features: it is centered on the transition as perceived by the actors who experience and manage it; it proposes a long-term conceptualization of the dynamics of farming systems, based on the farmer's initiative and creativity; and it highlights tools implemented by farmers during the transition to self-sufficiency and autonomy.

Optimisation of the traditional land-use system in the Angolan highlands using linear programming

This study used linear programming (LP) to analyse land-use alternatives in the traditional Umbundu farming system in the Angolan central highlands. Farmers of the region have traditionally produced maize and pulses for subsistence and vegetables and timber as cash crops. Different pasture and forest fallow rotations are used along catena production sites. The system is labour-intensive and uses animal traction. LP problems were formulated and solved for a baseline land-use alternative, improved diet alternative and maximal timber production alternative. All three problem formulations included constraints that guaranteed sufficient food and firewood production and sufficient pasture area for animals while being feasible in terms of human labour and animal traction consumption. Of the alternative production systems, cash crops with forest fallow had the highest land expectation value (LEV), while cereals under short grazing fallow showed even negative LEVs. Changing the diet by diversifying carbohydrate and protein sources increased LEV and reduced the need for women labour during the peak season. When timber production was maximised the optimal share of land devoted to pure forestry was 57%, and less labour was required.

Integrated crop–livestock systems in the Brazilian subtropics

In the subtropical region of Brazil, integrated crop–livestock systems (ICLSs) are characterized by the annual rotation of pastures and crops in a no-till system where the pasture component is used to produce either meat or milk. These systems focus on integration within the farm rather than between farms, being characterized by alternating cropping and pasturing in the same area. Independent of the crop rotations possible in a subtropical environment, the main integrated farming system found was rotation or succession of summer crops (Glycine max, Zea mays, Phaseolus vulgaris or Oryza sativa) with winter annual grazing grasses (mixed or solely Avena strigosa and Lolium multiflorum) or successive natural pastures.The high variability of crop yield in the Brazilian subtropics (due to climate extremes) as well as associated high costs and low prices has encouraged farmers to integrate livestock into their enterprises as a low-risk diversification option. Long-term experiments have demonstrated the benefits of crop–livestock integration with respect to many aspects of the soil–plant–animal system. There is evidence that such a system is not only a livestock–agriculture combination but also a unique system reaching a new complexity threshold, resulting in emergent properties with novel functionalities, some of which have yet to be investigated. In addition to greater environmental gains with less vulnerability, there are higher yields and more financial gain by the farmer, compared to that in the use of monocultures or non-integrated livestock farming. We conclude that ICLSs in Subtropical Brazil provide the opportunity for intensification with sustainability.

Soil organic carbon mineralization rates in aggregates under contrasting land uses

Measuring soil organic carbon (SOC) mineralization in macro-aggregates (250–2000μm), micro-aggregates (250–53μm) and the <53μm fraction helps to understand how spatial separation of SOC inside soil aggregates regulates its dynamics. We hypothesized that (i) compared with macro-aggregates SOC mineralization rate of micro-aggregates would be slower, (ii) adsorption of SOC on <53μm fraction decreases the SOC mineralization rate, and (iii) land use has a significant influence on SOC decomposition rate. To test these hypotheses we collected topsoil from Dermosol (Acrisols in FAO Soil Classification) sites under three contrasting land uses namely native pasture (NP), crop–pasture rotation (CP) and woodland (WL). Macro-aggregates, micro-aggregates and the <53μm fraction were separated from bulk soil by wet sieving. The three aggregate size ranges were then incubated for six months and CO2 evolution was measured at different time intervals. The chemically stable SOC of <53μm fraction of macro-aggregates, micro-aggregates and the <53μm fraction (separated by wet sieving) was measured by oxidation of SOC with 10% H2O2. On average, cumulative mineralization, Cmin (gCO2–Ckg−1 aggregate) of the <53μm fraction, was 28% lower than that of macro-aggregates and micro-aggregates. However, SOC mineralized (SOCmin) was similar in all size fractions. The size of slow SOC pool (percent of SOC concentration in aggregates) was also significantly higher in the <53μm fraction and ranged from 58 to 96%, across aggregate sizes. However, the chemically stable SOC (percent of SOC concentration in aggregates) was significantly higher in macro-aggregates and micro-aggregates than that of the <53μm fraction. Mean residence time (MRT) of slow SOC pool (MRTs) was higher in the <53μm fraction than for either macro-aggregates or micro-aggregates. Among the land uses NP had higher SOCmin compared with CP and WL. In conclusion, the insignificant difference in SOCmin, slow SOC pool sizes and MRTs between macro-aggregates and micro-aggregates indicated that SOC mineralization rate and thus the protection of SOC was similar in both macro-aggregates and micro-aggregates.

Management targets for continuously stocked mixed oat × annual ryegrass pasture in a no-till integrated crop–livestock system

Feeding livestock with cover crops can improve the efficiency and sustainability of integrated crop–livestock systems under no-till. However, no-till systems are based on permanent soil cover by organic material, so grazing livestock can compete for soil cover. Hence, managing stocking rates during the grazing period of the cultivated forage species is a key factor to assure enough herbage mass for maintaining long-term sustainable no-till systems. In this context, the objective of this study was to determine sward management targets for a continuously stocked mixed oat (Avena strigosa)×annual ryegrass (Lolium multiflorum) pasture in rotation with soybean in a no-till integrated crop–livestock system to determine the optimum balance between animal production and herbage mass for soil cover. The effects of sward height management on animal performance and herbage mass covers were evaluated. Treatments corresponded to four sward heights: 10, 20, 30 and 40cm, maintained throughout the experimental period through continuous stocking and variable stocking rate, plus a no-grazing control area. Treatments were arranged in a randomized complete block design with three replications. Herbage mass and animal performance increased linearly with sward height, but weight gain per hectare decreased. Grazing efficiency fitted to a quadratic regression and conversion efficiency a logarithmic model. Equilibrium between grazing and conversion efficiencies was reached on swards managed at 20cm, indicating that this sward height provided enough herbage mass to allow both animal performance and no-till crop demand for soil cover.

Integrated crop-livestock system in tropical Brazil: Toward a sustainable production system

Performance of soil management systems was initiated in 1995 in a field experiment in Dourados, MS, Brazil, with the following systems: CS – conventional tillage; NTS – no-tillage; ICLS – integrated crop-livestock with soybean (Glycine max (L.) Merr.) and pasture under no-till, rotating every two years, and PP – permanent pasture. Pastures (Brachiaria decumbens) were grazed by heifers with stocking rate adjusted to constant supply of forage. The hypothesis was that rotation of crops and pastures would be more efficient and present beneficial effects to the environment. More complex and diversified production systems may exhibit synergism between components to result in better soil physical structure, greater efficiency in use of nutrients by plants, greater accumulation of labile fractions of soil organic matter, greater diversity and biological activity in soil, and lower occurrence of nematodes and weeds. Better soil conditions in ICLS allowed greater resilience; over the years of assessment soybean and pasture yields were less affected by drought and frost. The ICLS was very efficient, accumulating soil C and reducing emissions of greenhouse gases. Soil quality was improved in integrated systems with larger number of components and greater interaction between these components (ICLS) compared to simple systems. Based on soil attributes, we affirmed in this long-term study that the ICLS system is agronomically and environmentally efficient and sustainable.

CYNARA CARDUNCULUS VAR. SYLVESTRIS IN DRY PASTURES OF NORTHERN LATIUM (CENTRAL ITALY): A PROPOSAL FOR MANAGEMENT

Cynara cardunculus L. var. sylvestris Lam. is a stenomediterranean element. Although sometimes it is abundant in specific areas, this plant is not widespread in Latium. In fact, it is mostly localized in the coastal areas and islands, in dry pastures and fallow lands, where it is part of a xerophilous plant community, very interesting from a floristic point of view. The study was conducted in 2007 at pSIC Acropolis of Tarquinia (IT6010039) on secondary origin prairies to provide information about their floristic composition and to define their optimal livestock density. Over 150 species were identified, some of which are listed as rare or poorly diffused in Latium, such as: Medicago muricoleptis Tineo, Malope malacoides L., Carlina lanata L., Cynara cardunculus var. sylvestris and Notobasis syriaca Cass. The livestock value estimated was 0.58 livestock units (LU) ha-1 year-1 on average. This value ensures the rational grazing management that must be guaranteed as necessary to maintain the high biodiversity of herbaceous communities, the aesthetic value of the landscape and the accessibility of the site, also in consideration of its high historical interest. In this sense, the study provides guidance on pasture management: grazing season, pasture rotation, livestock temporary load and control of the paddock time of use.