Template:Chapters 10.2

10.2 - Selection of dry season weeds as fodder

Katherine Trottier, University of Guelph, Canada

Suggested citation for this chapter.

Trottier,K. (2022) Selection of dry season weeds as fodder, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org

Introduction

Subtropical subsistence farmers face an annual extended seasonal drought that may lead to a period of hunger, affecting nearly 600 million people across the globe (Small & Raizada 2016). One of the most concerning issues with extended dry periods globally is the inability to maintain livestock at a productive level. Livestock offer many benefits to a household: they can provide meat, fibres, eggs, milk, and draft power. If markets are accessible, they can be locations for selling offspring for income. Livestock are an important factor in easing poverty. However, it is difficult for livestock to remain productive in the extended dry season without good quality forage. Providing feed can cost up to 70% of production expenses of animal products in developing countries, and it is often of poor nutritional value (Paul et al 2013).

By making use of native weeds that are adapted to drought conditions, there is an opportunity to provide good quality nutrition to livestock to ensure they remain productive and support the household (Small & Raizada 2016). However, this is a novel and potentially risky idea and should be approached with caution. Weeds can be an underutilized resource to assist in cropping systems; they are opportunistic and adapted to the local growing conditions during the dry season. By taking advantage of their growth, weeds have the potential to be cultivated in pure stands or intercropped with cereals for a source of fodder. Cultivating wild plants can also help reduce the pathogen load on future crops by increasing biodiversity within the cropping system, as well as suppressing other undesired weeds and nematodes (Small & Raizada, 2016).

Qualities to Consider

One study asked African subsistence farmers to list the most important qualities they required in forage legumes (Paul et al. 2016). The top two qualities, regardless of location, were nutrition content and yield. Other top qualities included improving soil fertility, erosion control, seed production, and palatability. The perceived importance depended on location. When evaluating locally-growing weeds, some factors to consider are:

-Ability to set and collect seed. The candidate species should be able to set seed that can be collected for use in a trial or for cultivation.

-Palatability and lack of toxicity. The candidate species needs to be accepted by livestock and not be harmful. Observe what species livestock graze on during the dry season over a long duration.

-Nitrogen-fixing capabilities. One of the most advantageous uses of legumes is their ability to convert atmospheric nitrogen into organic fertilizer through a symbiotic relationship with bacteria in their root nodules. The presence of nodules can be determined by examining plant roots and looking for small spheres with a magnifying glass.Symbiotic nitrogen fixation reduces the need for synthetic fertilizers, improves soil structure and deposits nitrogen for future crops or intercrops. More soil nitrogen creates higher yields for current and future crops (Navas et al. 2011). Legumes also increase soil organic matter and prevent soil erosion. Nitrogen-fixing properties of legumes decrease under drought conditions, therefore the nitrogen deposition in the soil may be lower than expected. This can be partially overcome by selecting for drought-tolerant species, such as vetch (Small & Raizada, 2016).

-Dormancy period. Some seeds require a period of time under certain conditions before the seeds will germinate. Ideally a plant should have a short dormancy period in order to grow when required.

-Grazing and cutting tolerance. Different plant species have different tolerances for grazing. Some species are very resistant to heavy grazing and close cutting; these are suitable for livestock species that browse closely to the ground like sheep. Cattle do not have the upper cleft lip that sheep do, and therefore cannot graze as closely.

-Lack of competition with main crops. A risk in cultivating weedy species is that the plants may grow unchecked and be difficult to manage in the next crop rotation. Species should be researched to ensure they can be easily controlled to prevent harming future crop yields. Methods of control include chemical control by herbicide application, and physical control by means of ploughing under. Many smallholder farmers will not have access to herbicides.

Establishing a trial

1.Observe livestock grazing during the dry season. The first step in selecting a species as a candidate is to observe which plants livestock eat during the dry season. This must be an extended period of observation to ensure consistency of palatability and lack of acute or long-term toxic effects.

2. Obtain seeds from selected plant species. To cultivate the weedy species as a crop, seeds must be collected and must be viable. Collected seeds can be planted out to determine the rate of germination. This would be important for evaluating the ease of cultivation. Ideally plants would have a low dormancy period in order to grow when required.

3.Establish a weight-gain trial to determine benefits for livestock. If possible, design a trial to establish whether there is a nutritional benefit when the candidate species is used as fodder. The trial should be composed of a control group and a test group: one group of livestock (the control group) should be fed the traditional dry season diet. The test group should be fed a modified diet, either the traditional diet supplemented with the candidate species, or solely the candidate species. Total amount of fodder between the two groups should be held relatively constant to ensure than any weight gain is not due to differences in food amounts. A way of assessing body condition should be established. A simple way to do so would be to compare body conditions of individual livestock at the beginning of the season with a body condition chart. (Please see the section “Resources for NGOs” for links to charts.) At the end of the season, each animal should then be re-evaluated and the scores should be averaged to determine whether the candidate weed species has a positive effect. A better and more accurate way of assessing this is by using a weight scale, where livestock are weighed before and after the trial. Other ways to assess changes in body condition would be differences in production. Milk production amounts could be measured, for milking species, or backfat thickness if animals are slaughtered during the dry season. If a trial is possible, it is highly recommended.

4.Introduce the species into a small trial. A small trial should be conducted to introduce the candidate species into a cropping system to ensure it is compatible. An example of this might be a small plot planted in the weed species during the dry season, followed by a traditional crop once the dry season has passed. This will investigate whether the candidate species is prone to “weediness” in subsequent crops; i.e. whether the growth of the candidate species can be controlled and will not grow unchecked beyond its cultivation. Another issue to note would be potential allelopathy, a phenomenon that occurs when a plant species produces toxins to inhibit the growth of another species in the same proximity. Since weeds are highly competitive, any survival mechanisms that damage crops must be ruled out before a weed can be considered to be a candidate crop.

5.Optimize agronomic conditions for the candidate species. Once it has been determined that a candidate species is both edible for livestock and not harmful to staple crops, refinement of cropping systems can be undertaken. A weed species can be grown in pure stands as a rotation crop or intercropped, depending on potential benefits or risks. To be successful, a dry season weed rotation crop must fit into the crop calendar and not interfere with the sowing of the subsequent staple crop. Potentially, the dry season crop could be relay cropped, sown as an intercrop prior to harvesting of the previous staple crop, to take advantage of residual moisture prior to the onset of the dry season.

Alternatively, leguminous weeds can offer benefits to cereals if intercropped and create a high-quality forage. One study in Nigeria found that the ideal planting ratio for forage legumes to cereals was a 2:2 ratio, compared to 3:1 and 1:3 ratios (Mohammed et al. 2015). This may be a good general rule of thumb to adopt. Some common cropping systems may have different ratios; for example, oat to vetch planting yields best at a 3:1 ratio, but for novel cropping systems it may be ideal to begin with a 2:2 ratio and adapt as needed in subsequent seasons (Bezabih et al. 2016). There may be nutritional benefits of intercropping.

Offering livestock multiple plant species may provide a wider range of nutrients, or a dilution of toxins or damaging nutrients in some species. For example, a specific plant may cause excess calcium levels in some livestock species. Intercropping such a plant with a low-oxalate crop would reduce the amount of calcium intake, hopefully below harmful levels while increasing the amount of feed and nutrition available.

To determine how to optimize agronomic conditions, trials should be conducted involving test and control plots. Differences between plots to note would include fodder and grain yield of both the dry season crop as well as all crops in the entire cropping system.

Critical Analysis The main issues associated with this strategy are possible toxicity to livestock and humans, the potential difficulty of collecting viable seeds, the weedy persistence of the candidate species beyond its intended agronomic season, and possible allelopathic properties associated with the candidate species. If it is possible, an internet search of the candidate species may aid in understanding any of these risks. If it is not possible, establishing trials and observing results will help evaluate whether the candidate weed is a desirable option. African subsistence farmers typically have a low rate of adoption for improved forages (Paul et al. 2013). The associated risks of using weedy species as fodder may be undesirable. However, there is a great need for innovation to mitigate the stress of extended dry periods on both humans and livestock. The cultivation of wild plants can also assist in global efforts to increase biodiversity in agricultural landscapes, as well as begin a domestication process to yield new crop species (Small & Raizada 2016). There is also the potential for business creation for smallholders selling seeds within their community. Cleaned seeds and chemically treated seed may assist in germination rates and could add value to the product, if they can be acquired.

Resources for NGOs

A review of the use of drought-tolerant leguminous weeds as fodder is available online. (Access at: https://agricultureandfoodsecurity.biomedcentral.com/articles/10.1186/s40066-017-0096-6)

The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and the International Centre for Agricultural Research in Dry Areas (ICARDA) are organizations with initiatives to develop drought-tolerant crops. (Access at: <http://www.icarda.cgiar.org/research-sub/biodiversity-and-its-utilization>.) (Access at: http://www.icrisat.org/>)

Body Condition Charts:

Beef Cattle: (Access at: https://pubs.ext.vt.edu/400/400-795/400-795_pdf.pdf)

Dairy Cattle: (Access at: http://www.omafra.gov.on.ca/english/livestock/dairy/facts/00-109.htm) Goats: (Access at: http://www2.luresext.edu/goats/research/BCS_factsheet.pdf)

Sheep: (Access at: http://www.ablamb.ca/images/documents/resources/health/bcs-sheep.pdf)

References

1.Alberta Lamb Producers. (accessed 2017). What’s the score: sheep. Body condition scoring (BSC) guide. Alberta Lamb Producers. Accessed online from: < http://www.ablamb.ca/images/documents/resources/health/bcs-sheep.pdf> (March 15 2017]

2.Bezabih, M., Mekonnen, K., Adie, A., & Thorne, P. (2016) Guidelines on the utilization of cultivated oatvetch and tree lucerne fodder in the Africa RISING sites of the Ethiopian highlands. Accessed online from: <https://cgspace.cgiar.org/bitstream/handle/10568/78175/AR_ethiopia_fodder_guideline_oct2016.pdf?sequence=1>. [February 12 2017]

3.Eversole, D. E., Browne, M. F., Hall, J. B., & Dietz, R. E. (2009). Body condition scoring beef cows. Virginia Cooperative Extension. Accessed online from: < https://pubs.ext.vt.edu/400/400-795/400-795_pdf.pdf>. [March 15 2017]

4.Mohammed, B., Gumel, I. A., & Muhammed, I. (2015). Compatability of Sorghum almum (Columbus grass) with three forage legumes. Journal of Aridland Agriculture. 1: 1-5.

5. Navas, M., Benito, M., Rodriguez, I., & Masaguer, A. (2011). Effect of five forage legume covers on soil quality at the Eastern Plains of Venezuela. Applied Soil Ecology. 49: 242-249.

6.Paul, B., Njenga, D., Mudavadi, P., Maass, B., Lukuyu, B. (2013). Evaluating farmers’ preferences for tropical forage legumes in smallholder farming systems in two contrasting agro-ecologies in Rift Valley, Kenya. Accessed online from: <https://www.researchgate.net/publication/260248359_Evaluating_farmers'_preferences_for_tropical_forage_legumes_in_smallholder_farming_systems_in_two_contrasting_agro-ecologies_in_Rift_Valley_Kenya>. [February 2 2017]

7.Rodenburg, J. (2012). Body condition scoring of dairy cattle. Ontario Ministry of Food, Agriculture, and Rural Affairs. Accessed online from: < http://www.omafra.gov.on.ca/english/livestock/dairy/facts/00-109.htm?>. [March 15 2017]

8. Small, F. A & Raizada, M. N. (2016). Mitigating dry season food insecurity in the sub-tropics by prospecting drought-tolerant, nitrogen-fixing weeds. Agriculture and Food Security (In press) (DOI 10.1186/s40066-017-0096-6)

9.Villaquiran, M., Gipson, T. A., Merkel, R. C., Goetsch, A. L., & Sahlu, T. (accessed 2017). Body condition scores in goats. American Institute for Goat Research. Accessed online from: < http://www2.luresext.edu/goats/research/BCS_factsheet.pdf> [March 15 2017]