Trade‐offs in the performance of alternative farming systems

Host–parasite coevolution can maintain high levels of genetic diversity in traits involved in species interactions. In many systems, host traits exploited by parasites are constrained by use in other functions, leading to complex selective pressures across space and time. Here, we study genome-wide variation in the staple crop Sorghum bicolor (L.) Moench and its association with the parasitic weed Striga hermonthica (Delile) Benth., a major constraint to food security in Africa. We hypothesize that geographic selection mosaics across gradients of parasite occurrence maintain genetic diversity in sorghum landrace resistance. Suggesting a role in local adaptation to parasite pressure, multiple independent loss-of-function alleles at sorghum LOW GERMINATION STIMULANT 1 (LGS1) are broadly distributed among African landraces and geographically associated with S. hermonthica occurrence. However, low frequency of these alleles within S. hermonthica-prone regions and their absence elsewhere implicate potential trade-offs restricting their fixation. LGS1 is thought to cause resistance by changing stereochemistry of strigolactones, hormones that control plant architecture and below-ground signaling to mycorrhizae and are required to stimulate parasite germination. Consistent with trade-offs, we find signatures of balancing selection surrounding LGS1 and other candidates from analysis of genome-wide associations with parasite distribution. Experiments with CRISPR–Cas9-edited sorghum further indicate that the benefit of LGS1-mediated resistance strongly depends on parasite genotype and abiotic environment and comes at the cost of reduced photosystem gene expression. Our study demonstrates long-term maintenance of diversity in host resistance genes across smallholder agroecosystems, providing a valuable comparison to both industrial farming systems and natural communities.

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Ecological-economic trade-offs of Diversified Farming Systems – A review

Ecological Economics ◽

10.1016/j.ecolecon.2019.03.002 ◽

2019 ◽

Vol 160 ◽

pp. 251-263 ◽

Cited By ~ 20

Author(s):

Julia Rosa-Schleich ◽

Jacqueline Loos ◽

Oliver Mußhoff ◽

Teja Tscharntke

Keyword(s):

Farming Systems ◽

Ecological Economic ◽

Trade Offs ◽

Diversified Farming Systems

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Investigating Farmer’s Perceptions of Adopting Alternative Farming Systems

Contributions to Economics - The First Decade of Living with the Global Crisis ◽

10.1007/978-3-319-24267-5_3 ◽

2016 ◽

pp. 33-45

Author(s):

Sotirios Papadopoulos ◽

Eleni Zafeiriou ◽

Christos Karelakis ◽

Theodoros Koutroumanidis

Keyword(s):

Farming Systems ◽

Alternative Farming

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Barriers to Agro-Ecological Intensification of Smallholder Upland Farming Systems in Lao PDR

Agronomy ◽

10.3390/agronomy9070375 ◽

2019 ◽

Vol 9 (7) ◽

pp. 375 ◽

Cited By ~ 3

Author(s):

Von Yi Yap ◽

Phaeng Xaphokhame ◽

Andreas de Neergaard ◽

Thilde Bech Bruun

Keyword(s):

Soil Fertility ◽

Cropping Systems ◽

Lao Pdr ◽

Farming Systems ◽

Crop Damage ◽

Extension Agents ◽

Selling Price ◽

Ecological Intensification ◽

Trade Offs ◽

Grazing Livestock

Intercropping of legumes can be a strategy to improve soil fertility and enhance overall productivity while reducing dependency on external inputs in intensified cropping systems. Integration of legumes in maize-based cropping systems is promoted as an agro-ecological intensification option for input-constrained smallholders in uplands of Southeast Asia, but adoption rates in the region remain low. The overall aim of this study was to assess the suitability and trade-offs of integrating ricebean in maize-based smallholder cropping systems in upland areas of Northern Laos. We conducted a researcher-managed field trial to investigate the agronomic performance of ricebean/maize intercropping, and farmer-managed trials combined with surveys (N = 97), and focus group discussions in 10 villages to understand factors influencing farmers’ decision making concerning ricebean adoption. Drought, rat infestation and crop damage by grazing livestock were identified as important constraints to the production of ricebeans. Factors facilitating adoption included improvement of soil fertility, the potentially high selling price of ricebeans and the presence of extension agents, while barriers included labour shortage, concerns about competition with maize and lack of a market outlet for the ricebean produce. We conclude that the investigated maize/ricebean intercropping system is poorly suited to the current conditions in the study area, and call for farm-based studies focusing on developing locally adapted legume intercropping systems able to perform under variable rainfall conditions. Initiatives addressing challenges related to free grazing livestock and efforts to link legume producers in remote areas to emerging markets are also needed.

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Comparison of alternative farming systems. III. Soil aggregate stability

American Journal of Alternative Agriculture ◽

10.1017/s0889189300004884 ◽

1993 ◽

Vol 8 (1) ◽

pp. 27-33 ◽

Cited By ~ 34

Author(s):

J.L. Jordahl ◽

D.L. Karlen

Keyword(s):

Soil Water ◽

Soil Aggregates ◽

Organic Matter Content ◽

Aggregate Stability ◽

Farming Systems ◽

Animal Manure ◽

Matter Content ◽

Water Stability ◽

Alternative Farming ◽

Alternative Practices

AbstractQuantitative studies are needed to separate the real and supposed benefits of alternative farming practices. Our objective was to learn how conventional and alternative practices on adjacent farms in central Iowa affected the water stability of soil aggregates. We collected samples of Clarion loam (fine-loamy, mixed, mesic Typic Hapludoll) from adjacent 16 ha fields in fall 1990 and spring 1991. Aggregate stability was determined by wet-sieving and by measuring turbidity of soil-water suspensions. The combined effects of alternative practices resulted in greater water stability of soil aggregates, higher soil organic matter content, and lower bulk density compared with conventional practices. The components of the alternative system that were mainly responsible for these differences were: rotations that included oat and hay crops; ridge-tillage; and additions of 45 Mg/ha of a mixture of animal manure and municipal sludge during the first 3 years of each 5 year rotation. The more favorable soil physical conditions, shown by increased water stability of soil aggregates, presumably will improve soil water regimes and reduce long-term soil erosion losses from the alternatively managed fields.

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Comparison of alternative farming systems. I. Infiltration techniques

American Journal of Alternative Agriculture ◽

10.1017/s0889189300004860 ◽

1993 ◽

Vol 8 (1) ◽

pp. 15-20 ◽

Cited By ~ 19

Author(s):

S.D. Logsdon ◽

J.K. Radke ◽

D.L. Karlen

Keyword(s):

Farming Systems ◽

Farming System ◽

Water Infiltration ◽

Silty Clay ◽

Double Ring ◽

Infiltration Rates ◽

Single Ring ◽

Alternative Farming ◽

Surface Soil Properties ◽

Infiltration Techniques

AbstractQuantitative data are needed to understand how alternative farming practices affect surface infiltration of water and associated surface soil properties. We used a rainfall simulator, double ring infiltrometer, small single ring infiltrometers, and tension infiltrometers to measure water infiltration for Clarion loam (fine-loamy, mixed, mesic Typic Hapludoll) and for Webster silty clay loam (fine-loamy, mixed, mesic Typic Haplaquoll) soils located on a conventionally-managed and an alternatively-managed farm in central Iowa. Steady-state measurements suggested that infiltration rates were somewhat higher for the alternative farming system. Bulk densities were sometimes lower, and volume of large pores was a little higher for the alternative farming system. Small single rings were more reproducible than rainfall simulators or double ring infiltrometers, and data trends were the same as for rainfall simulators.

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Reply to van Donge

The Journal of Modern African Studies ◽

10.1017/s0022278x02003932 ◽

2002 ◽

Vol 40 (2) ◽

pp. 313-320 ◽

Cited By ~ 1

Author(s):

Stefano Ponte

Keyword(s):

Rural Livelihoods ◽

Farming Systems ◽

Agrarian Change ◽

Economic Diversification ◽

Uluguru Mountains ◽

Alternative Farming ◽

Economic Ties ◽

The Impact ◽

Good Access

Van Donge's comment on my reassessment of agrarian change on the Uluguru Mountains, Tanzania, raises a number of issues that go beyond the specificities of the location under scrutiny. Before dealing with these, however, let me restate my argument, which van Donge has reconstructed only selectively. In my article (Ponte 2001a), I argued that rural households are not ‘trapped in decline’ on the Uluguru Mountains, as depicted in previous literature. Although agriculture is not going through an easy transition in the area, and some options are becoming more limited, others are being more skilfully utilised. On the Uluguru Mountains, land scarcity is the main feature of agriculture; deforestation and soil erosion are major problems; and inputs have become increasingly expensive. Under these circumstances, the main ways households can improve their quality of life – short of leaving the area altogether, and in addition to relying on remittances from outside – are to expand land cultivated in other locations, to experiment with alternative farming systems, and to increase non-farm incomes. I observed that Uluguru households were doing all of these in the mid-1990s, and that their income levels and housing characteristics had improved. This was intriguing and challenging to me, since farmers' adaptations to changing markets had not led to higher incomes in other areas that I had researched in Tanzania. Finally, I suggested that economic diversification can play an important role in improving rural livelihoods, but that this process is more likely to take place in locations with well-established economic ties and relatively good access to major markets.Van Donge has a variety of problems with my argument. These can be grouped around three main themes: (1) issues of methodology; (2) a perceived misunderstanding of his argument; and (3) the impact of liberalisation. Due to space limitations, in my reply to van Donge I deal with these larger themes. A more detailed response covering specific evidence and technicalities is available from this author and has been sent to van Donge.

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