Research Papers
Suppressing weed growth after wheat harvest with underseeded red clover in organic farming
- Randy L. Anderson
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- Published online by Cambridge University Press:
- 05 March 2015, pp. 185-190
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Organic producers are seeking alternative tactics for weed control so that they can reduce their need for tillage. In this study, we examined cover crop strategies for suppressing weed growth after harvest of wheat. Three cover crop treatments, red clover (mammoth type), a mixture of oat and dry pea, and a control were compared. Treatments were established in both winter and spring wheat, resulting in six treatments arranged in a randomized complete block design. Red clover was underseeded in wheat by drilling in the spring, and the oat/pea mixture was planted in August. Oat was planted uniformly across all treatments in the following growing season. The red clover treatment effectively suppressed weeds, reducing post-harvest weed biomass, density of volunteer winter wheat, and seed production of downy brome by more than 99% compared with the control. Oat/pea was not effective for weed management, likely because of less fall growth and competition compared with red clover. Underseeding red clover did not affect winter wheat yield, but reduced spring wheat yield by 17%. Oat yield, however, was reduced by volunteer crop plants and downy brome infestations in all treatments. Underseeding clovers in winter wheat may effectively manage weeds and, if they winterkill, can replace the need for tillage to control weeds after wheat harvest.
Food waste in campus dining operations: Inventory of pre- and post-consumer mass by food category, and estimation of embodied greenhouse gas emissions
- Christine Costello, Esma Birisci, Ronald G. McGarvey
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- Published online by Cambridge University Press:
- 21 May 2015, pp. 191-201
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There are many economic, social and environmental reasons to reduce the occurrence of food that is wasted. As communities consider options for managing their food waste streams, an understanding of the volume, composition and variability of these streams is needed to inform the decision-making process and potentially justify the capital investments needed for separation and treatment operations. This more detailed inventory also allows for the estimation of embodied resources in food that is wasted, demonstrated herein for greenhouse gas emissions (GHGs). Pre- and post-consumer food waste was collected from four all-you-care-to-eat Campus Dining Services (CDS) facilities at the University of Missouri, Columbia over 3 months in 2014. During the study period approximately 246.3 metric tons (t) of food reached the retail level at the four facilities. 232.4 t of this food was served and 13.9 t of it (10.1 t of edible and 3.8 t of inedible), was lost as pre-consumer waste. Over the same time period, an estimated 26.4 t of post-consumer food waste was generated at these facilities, 21.2 t of the waste edible and 5.3 t of it inedible. Overall, 5.6% of food reaching the retail level was lost at the pre-consumer stage and 10.7% was lost at the post-consumer stage. Out of the food categories examined, ‘fruits and vegetables’ constituted the largest source of food waste by weight, with grains as the second largest source of food waste by weight. GHGs embodied in edible food waste were calculated. Over the study period an estimated 11.1 t CO2e (100-yr) were embodied in the pre-consumer food waste and 56.1 t were embodied in post-consumer food waste for a total of 67.2 t. The ‘meat and protein’ category represents the largest embodiment of GHG emissions in both the pre- and post-consumer categories despite ranking fourth in total weight. Beef represents the largest contribution to post-consumer GHG emissions embodied in food waste with an estimated 34.1 t CO2e. This distinction between the greatest sources of food waste by weight and the greatest sources of GHG emissions is relevant when considering alternative management options for food waste.
Coping with food poverty in cities: The case of urban agriculture in Glen Norah Township in Harare
- Steven Masvaure
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- Published online by Cambridge University Press:
- 20 May 2015, pp. 202-213
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The focus of this study is on urban agriculture which is a common informal sector activity across most sub-Saharan African cities. Urban agriculture is more common among poor urban households, and acts as a poverty coping mechanism. Poor households often spend more than 60% of their income on food alone. The major thrust of this study was to understand the underlying mechanisms driving farming in cities. A mixed method research approach was adopted and data was collected from 103 households in Glen Norah Township in Harare, Zimbabwe through semi-structured interviews, questionnaires and observations. Arising from analysis of the data, the Urban Livelihoods Coping Model (ULCM) is proposed in order to explain the phenomenon of urban agriculture in African cities. This model acknowledges the fact that the socio-economic conditions and the socio-historical context of Zimbabwe and other African countries today is as a result of the influence of ‘Western leaning’ development policies influenced by modernization and associated theories. These theories combined with cultural factors and the impact of Structural Adjustment Policies resulted in the present situation where urban agriculture plays a critical role in the survival of the urban poor as a coping mechanism against food poverty. The ULCM ascribes the emergence of urban agriculture to necessity, ability and opportunity. The significance of this study is that it will contribute to understanding the socio-economic role of urban agriculture and how it can be factored into the urban planning systems of developing countries.
Winter legume cover-crop root decomposition and N release dynamics under disking and roller-crimping termination approaches
- Arun D. Jani, Julie Grossman, Thomas J. Smyth, Shuijin Hu
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- Published online by Cambridge University Press:
- 20 May 2015, pp. 214-229
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Several approaches can be used to terminate legume cover crops in the spring prior to planting summer crops, but the effect that these methods have on decomposition and nitrogen (N) release dynamics of legume cover-crop roots is poorly understood. The main objectives of this study were to: (i) quantify decomposition and N release of roots from pea (Pisum sativum), clover (Trifolium incarnatum) and vetch (Vicia villosa Roth); (ii) determine if roots decompose and release N faster when cover crops are terminated by disking compared with roller-crimping; and (iii) determine if roots decompose and release N faster under higher soil inorganic N levels. Two field experiments were conducted in Goldsboro and Kinston, North Carolina in the summer of 2012. Cover crops at these sites were terminated in spring by disking or roller-crimping and planted to unirrigated corn. Air-dried roots placed in litterbags were buried in their corresponding cover-crop plots and in plots where cover crops had not been grown that had either synthetic N fertilizer added at burial or had no fertilizer addition. Root litterbags were collected over 16 weeks at both sites. Cover-crop plots terminated by disking had up to 117 and 49% higher soil inorganic N than roller-crimped plots in Goldsboro and Kinston, respectively. However, roots did not appear to contribute significantly to these increases, as measured root decomposition and N release was not affected by termination approach at either site. Roots decomposed rapidly at both sites, losing up to 65% of their original biomass within 4 weeks after burial. Root N release was also rapid at both sites, with vetch generally releasing N fastest and clover slowest. It was estimated that cover-crop roots supplied 47–62 and 19–33 kg N ha−1 during the corn cycle in Goldsboro and Kinston, respectively. Our results indicate that under the warm, humid summer conditions of the Southeastern USA, legume cover-crop roots decompose and release N rapidly.
The role of US organic certifiers in organic hotspot formation
- I. Julia Marasteanu, Edward C. Jaenicke
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- Published online by Cambridge University Press:
- 22 June 2015, pp. 230-245
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The purpose of this paper is to investigate the formation of hotspots of organic operations (geographically close areas that have positively correlated high numbers of organic operations), paying particular attention to the role of the organic certifying agent. We analyze the association of county-level factors related to policy, economics, demographics and organic certifiers with the probability that a county is in a hotspot or coldspot (geographically close areas that have positively correlated low numbers of organic operations) of organic operations. The results suggest that a high presence of government run organic certifying agents, as well as a high presence of private organic certifying agents who provide outreach services, are both positively associated with the probability that a county belongs to a hotspot. Other factors, such as the level of property taxes and the distance of the county from the nearest interstate, are also significantly correlated with the probability that a county is in a hotspot. Understanding factors associated with organic hotspots is important given the surge in momentum in the organic industry and the concerns that demand for organic products may be outpacing domestic supply. In particular, understanding the role that certifiers play in the formation of organic hotspots is important, as certain services provided by certifiers may be indicative of the level of communication between organic operations and their communities. The results of this paper may encourage public institutions that approve and regulate organic certifiers to provide incentives for offering outreach services, and private institutions interested in promoting organic operations to work more closely with certifying agents as a means to boost organic hotspots.
Assessing the social and economic benefits of organic and fair trade tea production for small-scale farmers in Asia: a comparative case study of China and Sri Lanka
- Yuhui Qiao, Niels Halberg, Saminathan Vaheesan, Steffanie Scott
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- Published online by Cambridge University Press:
- 08 June 2015, pp. 246-257
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Organic agriculture has the potential to provide improved livelihood opportunities, increased income and social benefits for resource-poor small-scale farmers. It has thus become a popular strategy for economic development and poverty reduction in many areas of the global south. However, there has been limited empirical research regarding the actual benefits of certified organic production, particularly when organic is combined with fair trade certification, and for small-scale farmers who are not engaged in coffee or banana production. Further research is needed to demonstrate experiences of farmers under diverse socioeconomic conditions, organizational contexts and degrees of market access. To address these gaps, two surveys of certified organic and fair trade tea producers in China and Sri Lanka were undertaken to investigate the contributions of organic crops to the household economy. In both cases, organic production required lower investment in terms of external inputs but a higher input of farmers’ labor. The price premium received by farmers for the organic tea compensated for the extra labor input and lower yield, resulting in a net profit. However, given the relatively small plots of tea gardens of each household, organic production could not fully provide for the households’ livelihood. Non-farm income dominated the total income of the households across the study cases, despite the earnings from organic farming. In both sites, market-oriented organic tea projects have created more options for paid work locally, which benefits women of reproductive age. Social benefits of organic farming were also reported. Pursuing fair trade certification on top of organic production facilitated farmer organizing, training and community development. Organic agriculture and fair trade certification offer important prospects to improve the livelihoods of small-scale farmers in other, less favored areas of Asia. These forms of certified production could provide economic and social benefits in instances where farm income is the main source of household income.
Influence of organic manures on carrot (Daucus carota L.) crops grown in a long-term field experiment in Sweden
- Lars Kjellenberg, Eva Johansson, Karl-Erik Gustavsson, Artur Granstedt, Marie E. Olsson
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- Published online by Cambridge University Press:
- 22 June 2015, pp. 258-268
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This study evaluated the effects of organic agriculture manuring systems on carrot (Daucus carota) root morphology and sugar and polyacetylene content. Carrots were harvested three times per season 2006–2007 in a long-term field experiment at Skilleby research farm, Sweden. The effects of pelleted chicken manure, fresh farmyard manure and composted farmyard manure (COM) were compared against control plots left unmanured since the field experiment started in 1991. The carrots were analyzed for root size, root shape, amount of soluble sugars and amount of falcarinol-type polyacetylenes. Differences between manuring systems were found to be smaller than the variation between harvest years and harvest occasions, probably due to the grass-clover ley included in the crop rotation system. On an average for the six harvests, manuring with COM increased root length by 6% compared with fertilizing with pelleted chicken manure. Carrots fertilized with pelleted chicken manure also had 6–7% lower total soluble sugar content than carrots manured with 50 t ha−1 of composted or fresh manure. The falcarinol to total falcarinol-type polyacetylenes ratio was 15.4% in carrots manured with 50 t ha−1 of composted or fresh manure and 14.7% in carrots fertilized with pelleted chicken manure. Seasonal fluctuations in falcarinol-type polyacetylenes were more pronounced in carrots manured with fresh or composted manure than in carrots fertilized with pelleted chicken manure. The results suggest that manuring organic carrots with compost may be the most beneficial strategy, at least in systems where fertilizer is applied only once per crop rotation, whether directly to the carrot crop or in the preceding crop.
Organic grass pea (Lathyrus sativus L.) seeds as a protein source for weaned piglets: Effects of seed treatment and different inclusion rates on animal performance
- L. Baldinger, W. Hagmüller, U. Minihuber, M. Schipflinger, W. Zollitsch
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- Published online by Cambridge University Press:
- 22 June 2015, pp. 269-279
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Organically produced pork occupies only a small niche in the European meat market, with one of the main reasons being the shortage of locally produced high-quality protein sources. In an effort to promote currently under-utilized protein sources, two feeding trials were conducted with grass pea seeds as feed for weaned piglets. The grass pea (Lathyrus sativus L.) is a hardy grain legume that produces protein-rich seeds, but, as other grain legumes, it contains several anti-nutritive compounds. Apart from trypsin inhibitors and tannins, it also contains the neurotoxin β-N-oxalyl-L-α,β-diaminopropionic acid (ODAP) which may cause nerve damage in farm animals as well as humans. The content of both trypsin inhibitors and ODAP can be greatly reduced by hydrothermal treatment; therefore both raw and hydrothermally treated grass pea seeds were used in the two feeding trials. Diets were fed to 152 and 144 piglets [crosses of (Pietrain × Duroc) × (Landrace × Large White)] respectively, during their rearing phase directly after weaning. In experiment 1, a control diet was compared with two diets containing 10 and 20% raw grass pea seeds, plus one diet with 20% treated grass pea seeds, respectively (as fed basis). In experiment 2, a control diet was compared with one diet containing 20% raw grass pea seeds and two diets containing 20 and 30% treated grass pea seeds, respectively (as fed basis). Grass pea seeds contained 265 and 271 g kg−1 crude protein (as fed basis) in the first and second experiment, respectively, and had an amino acid profile similar to peas (Pisum sativum), including relatively low contents of methionine and cysteine. Hydrothermally treated grass pea seeds were found to be a valuable protein source that was well accepted by piglets. At an inclusion rate of 20–30% in diets, feed intake and daily weight gain of piglets was very similar to that of the control treatment. However, including 20% raw grass pea seeds had a significant negative effect on feed intake in experiment 1 and on daily weight gain in experiment 2. Therefore, hydrothermal treatment of grass pea seeds is recommended prior to feeding to piglets.