We evaluated the impact of incorporating cover crops (CC) in commercial potato production, primarily to alleviate the severe soil erosion recorded in Mediterranean climate agriculture. As part of a 3-year study on this subject, we have developed complete agronomic management practices that enable sowing, growing and harvesting potatoes in soil covered with CC. This management scheme includes adjustment of specific management practices and farming machinery. In this paper, we explore the impact of including CC in potato production on runoff and soil erosion, weed suppression, and potato yield and quality. These are evaluated at the environmental, agronomic and economic levels. Our results clearly show that potato production under CC generates no yield reduction or nutrient deficiencies, reduces soil erosion by 95% and reduces runoff by more than 60%. Incorporation of CC in potato-growing practices also results in suppression of weeds (both species and biomass). The direct benefit to the grower from CC adoption is estimated at a 1.3% savings in variable costs of production. The benefit for the grower, along with additional environmental benefits translated to economic public goods calls for public intervention to support the transition from the conventional practices to CC practiced is essential.

BACKGROUND: Potato tubers from the STBd somatic hybrid line that exhibited improved tolerance to salinity and resistance to fungal and PVY infections were characterised. They were compared for their chemical composition to the Spunta variety produced by conventional agronomic practices. This study aimed to compare nutritional value and safety by feeding rats with STBd or commercial tubers added to the standard diet (20/80 w/w). RESULTS: The analysis of soluble sugar, fat, fibre and ash content of tubers did not reveal any significant differences between the hybrid line and the control Spunta variety. Small differences were observed in dry matter, starch and protein content of hybrid potatoes in comparison to controls. However, all values were within normal ranges reported in the literature. The feeding study on rats showed that overall health, weight gain, food consumption, morphological aspects and weights of organs were comparable between rat groups fed the STBd hybrid and the Spunta variety. CONCLUSION: Taken together, 28 days of consumption of STBd hybrid potato did not exert any adverse effect on rats compared with commercial Spunta potato. The STBd potato line was therefore considered to be as safe for food utilisation as the commercial variety. © 2014 Society of Chemical Industry

Irrigation is one of the agronomic practices seldom employed by potato growers, either because of water unavailability or lack of knowledge of the benefits of the appropriate water use. In order to demonstrate this benefit, in a cycle of five months, regarding of a commercial crop located in Tenjo (Cundinamarca), we evaluate the response of the potato variety Diacol Capiro R-12 to three treatments, fertigation (T1), drip irrigation (T2), and the comparison with a conventional check without irrigation (T3), distributed under a completely randomized design. The influence of the treatments on the fresh and dry weight of leaves, stems and tubers was estimated. Throughout the assessment, the irrigation and fertigation treatments were superior to conventional one, showing statistically significant differences at harvest time, where treatment T1 showed an increase in yield of 72% and treatment T2 of 18%, compared with the control. Based on the results, fertigation can be considered as an option for farmers to increase their potato profitability and market competitiveness, since the impact generated by price fluctuations of the product can be reduced, obtaining higher and more constant yield per area unit, regardless of weather conditions during the crop cycle.

Potato, dry bean, and sugar beet production have increased markedly in recent years on irrigated cropland in Alberta, Canada. Concerns exist about declining soil quality and increased soil erosion when these low-residue crops are grown in sequence in short-duration rotations. A 12-yr rotation study was conducted to determine the merits of adopting various conservation practices (reduced tillage, cover crops, composted manure) and longer-duration rotations to develop a more sustainable production system for these row crops. This article reports on weed density and weed seedbank data collected in the study. Weed densities recorded prior to applying postemergence herbicides indicated that conservation compared with conventional management treatments had greater weed densities in 30 to 45% of the cases in 3-, 4-, and 5-yr rotations. In contrast, a 6-yr conservation rotation that included 2 yr of timothy forage resulted in similar or lower weed densities than rotations with conventional management practices. Residual weed densities recorded 4 wk after applying postemergence herbicides were only greater in conservation than conventional rotations in 2 of 12 yr, regardless of rotation length. Weed seedbank densities at the conclusion of the 12-yr study were similar for 3- to 6-yr rotations under either conservation or conventional management. These findings indicate that implementing a suite of conservation practices poses little risk of increased weed populations in the long term. This knowledge will facilitate grower adoption of more sustainable agronomic practices for irrigated row crops in this region.Nomenclature: Dry bean, Phaseolus vulgaris L.; oat, Avena sativa L.; potato, Solanum tuberosum L.; rye, Secale cereale L.; sugar beet, Beta vulgaris L.; timothy, Phleum pratense L.; wheat, Triticum aestivum L.

This data study contains data related to participatory variety selection (PVS) and double cropping of cereals, broad beans, and potato. Project title: Second Agreement Africa RISING (Research in Sustainable Intensification for the Next Generation: ILRI Contract No. ASSP-14/2014 Project abstract: The Ethiopian highlands are characterized by cereal-food legume production system where the productivity is very low due to pests, poor agronomic practices and growing of unimproved cultivars. Potato is becoming an integral parts of the production system of the highlands. Sustainability of cereals (wheat and barley) and potato is maintained through regular rotation with food legumes in small and main rainy seasons of the highlands. During the implementation of Africa RISING (AR) in Bale highlands and other projects, it was possible to identify high yielding cereal, broad beans and potato cultivars that can provide high yield and contribute to food security. However, many varieties are not tested in all the four AR sites. Moreover, there are early maturing legumes that can be used in double cropping with cereal and potato to increase land productivity in the highlands. Most of the wheat, barley, potato and broad beans cultivars released are developed with little or involvements of farmers and hence there is a need to put these varieties under PVS where farmers? inputs will be considered. Therefore, this study/intervention is designed to evaluate cultivars of the four commodities following PVS approaches as well as testing double cropping to increase land productivity. Project website: http://africa-rising.net | IFPRI1; Africa Rising

This data study contains data related to participatory variety selection (PVS) and double cropping of cereals, broad beans, and potato. Project title: Second Agreement Africa RISING (Research in Sustainable Intensification for the Next Generation: ILRI Contract No. ASSP-14/2014 Project abstract: The Ethiopian highlands are characterized by cereal-food legume production system where the productivity is very low due to pests, poor agronomic practices and growing of unimproved cultivars. Potato is becoming an integral parts of the production system of the highlands. Sustainability of cereals (wheat and barley) and potato is maintained through regular rotation with food legumes in small and main rainy seasons of the highlands. During the implementation of Africa RISING (AR) in Bale highlands and other projects, it was possible to identify high yielding cereal, broad beans and potato cultivars that can provide high yield and contribute to food security. However, many varieties are not tested in all the four AR sites. Moreover, there are early maturing legumes that can be used in double cropping with cereal and potato to increase land productivity in the highlands. Most of the wheat, barley, potato and broad beans cultivars released are developed with little or involvements of farmers and hence there is a need to put these varieties under PVS where farmers? inputs will be considered. Therefore, this study/intervention is designed to evaluate cultivars of the four commodities following PVS approaches as well as testing double cropping to increase land productivity. Project website: http://africa-rising.net

The effect of spacing and nutrient management on physiological and biochemical properties of orangefleshed  sweet potato var. Gouri was studied under foot hill conditions of Manipur. The physiological  parameters such as relative water content (RWC) and chlorophyll stability index (CSI); biochemicalparameters such as protein content, total soluble sugar (TSS) and reducing sugar (RS) and NPK  contents in leaves and tubers showed significant variation due to spacings (S1: 60 x 20 cm and S2: 60  x 30 cm) and NPK rates (F1: 60:40:60 ; F2: 75:50:75; F3: 90:60:90 kg ha-1). The RWC and CSIincreased with increasing nutrient doses under spacing S1 and decreased at spacing S2. The NPK  content, TSS and RS in leaf tissues increased significantly with increasing doses of NPK. The leaf  protein content increased with increasing rates of NPK at wider spacing (S2). The treatment  combinations, S1F2 (33.0 t ha-1) and S2F3 (32.7 t ha-1) produced significantly higher tuber yield. Thestudy revealed that NPK @ 75:50:75 kg ha-1 and spacing of 60 x 20 cm can be recommended for  higher productivity and tuber quality of sweet potato under foot hill conditions of Manipur.

Keywords: Irish potato, food security, stakeholder analysis, sustainability indicators, Cool Farm Tool-Potato, yield gap, resource use efficiency, LINTUL-POTATO model, Zimbabwe. Oniward Svubure (2015). Agronomic and environmental studies of potato (Solanum tuberosum L.) and analysis of its value chain in Zimbabwe. PhD thesis, Wageningen University, The Netherlands, with English summary, 220 pp. Irish potato is food for more than a billion people worldwide. In Zimbabwe, Irish potato is becoming an important food crop. The government declared it a national strategic food security crop on 18 May 2012. This major policy pronouncement, qualified Irish potato for government initiated farmer support initiatives such as mechanisation and irrigation capacity building. The growing importance of potato as a food crop is prefaced on rising food insecurity in the country coupled with the impact of the radical land reform of 2000 on agricultural production. The land reform completely restructured commercial agriculture when about 96 % of the original 12.5 million ha of large-scale commercial farmland in 1980 was taken up for resettlement by 2010. Two resettlement models were used, the A1 and A2 resettlement models. The former resembles the communal area land allocation system while the later are self-contained small to medium scale farm units ranging about 35 to 300 ha. The newly resettled farmers have started growing potato adding to the already existing communal area and the few remaining large-scale commercial farmers. It is in this context that the potential of the new agrarian structure to sustainably increase Irish potato production was investigated. Increasing potato production on a sustainable basis will enable the crop to assert itself as a national strategic food security crop and help ease the food security challenges the country is grappling with. A grower survey was conducted on the cultural practices, input use, average yield, and infrastructure for potato production. The survey data was used to categorise the growers. Only growers with a minimum 5 years continuous potato growing experience were targeted making the data collected dependable. Grower resource footprints of land, water, biocides and nutrients were calculated based on the actual yield, Ya. Further, the Ya data collected were used to calculate the yield gap, YG, based on the yield of the best performing growers, Yh, simulated yield potential, Yp, and water-limited potential yield, Yw, of the respective agro-ecological areas. The LINTUL-POTATO model was used to estimate Yp, Yw and water need. This model simulates potential dry matter production based on radiation use efficiency of intercepted light by the potato crop. Another model, the Cool Farm Tool-Potato was used to further distinguish and appraise the production systems in terms of yields, inputs and efficient use of energy as reflected in their CO2 balances. The model calculates the contributions of various production operations to the total greenhouse gas (GHG) emission. Consequently, grower practices which contribute the most to the GHG emission were identified and generic mitigation measures for each production system were suggested. Realising the growing importance of sustainability issues in agricultural production and the scarcity of evaluation protocols in cropping systems, the study developed a framework that can be used to evaluate cropping systems. The framework was constructed using the potato-based cropping systems in the Eastern Highlands of Zimbabwe. Finally, instead of just focusing on the production related aspects only, the study also took into cognisance the need to understand the performance of the entire Irish potato sector in Zimbabwe. A value-chain analysis was therefore conducted to evaluate the performance the Irish potato sector in the country. Irish potato production in Zimbabwe is still low. Experts estimate annual production at nearly 120,000 t from around 6,000 ha. The large-scale commercial and the A2 resettlement are large-scale, high input and mechanised systems with an average potato area of 9 ha per planting. The communal area and A1 resettlement are smallholder low input systems with average potato area per planting of 0.8 ha and animal-drawn equipment is used. On resource use efficiencies, the actual tuber yield ranged from 8 – 35 t/ha across all systems representing a yield gap of over 77 %. Comparing with the simulated average potential yield, the mean actual yield observed ranged from 8 to 35 % of the simulated potential yield, translating to a yield gap of 65 to 92 %. Hence there is a large potential to increase potato production in these environments. The nutrient use efficiencies range were: 97 to 162 g potato g-1 N, 93–105 g potato g-1 P2O5 and 97–123 g potato g-1 K2O. This was anticipated because of the high synthetic fertiliser use and the low actual yields reported. The biocide use efficiencies ranged from 0.5 to 0.9 kg potato g-1 active ingredient (a.i.) fungicide, and 8 to 15 kg potato g-1 a.i. insecticide. Regarding water use, the average water use efficiency based on irrigation water and rainfall, ranged from 2 to 6 g potato l-1, while the simulated potential water use efficiency from irrigation and precipitation ranged from 9 to 17 g potato l-1. The large gap observed between actual and potential water use efficiency shows the scope to improve crop management practices to increase actual yield while lowering irrigation water. On the CO2 balance of the systems, a high carbon footprint was reported with an average of 251 kg CO2 eq./t potato. The least average carbon footprint was 216 kg CO2 eq./t potato for the communal area, while the A2 resettlement system had the highest of 286 kg CO2 eq./t potato. The high carbon footprint was anticipated as a reflection of the systems’ inefficiencies in terms of low yields and high input use. Focussing on the performance of the entire Irish potato sector, value chain analysis showed considerable levels of value-addition and gross profit of at least 13 % at each linkage. While the sector enjoys government policy support, major factors impacting on the value-chain performance relate to high potato production costs, low yields, and lack of farmer training. On the proposed framework on cropping sustainability, the indicator thresholds serve to monitor farmer progress as they improve their practices towards the desired direction of sustainability. This study demonstrated that there is tremendous potential to increase potato output and help ease the food insecurity challenges the country currently faces.

<strong>Keywords:</strong> Irish potato, food security, stakeholder analysis, sustainability indicators, Cool Farm Tool-Potato, yield gap, resource use efficiency, LINTUL-POTATO model, Zimbabwe. Oniward Svubure (2015). Agronomic and environmental studies of potato (<em>Solanum tuberosum</em> L.) and analysis of its value chain in Zimbabwe. PhD thesis, Wageningen University, The Netherlands, with English summary, 220 pp. Irish potato is food for more than a billion people worldwide. In Zimbabwe, Irish potato is becoming an important food crop. The government declared it a national strategic food security crop on 18 May 2012. This major policy pronouncement, qualified Irish potato for government initiated farmer support initiatives such as mechanisation and irrigation capacity building. The growing importance of potato as a food crop is prefaced on rising food insecurity in the country coupled with the impact of the radical land reform of 2000 on agricultural production. The land reform completely restructured commercial agriculture when about 96 % of the original 12.5 million ha of large-scale commercial farmland in 1980 was taken up for resettlement by 2010. Two resettlement models were used, the A1 and A2 resettlement models. The former resembles the communal area land allocation system while the later are self-contained small to medium scale farm units ranging about 35 to 300 ha. The newly resettled farmers have started growing potato adding to the already existing communal area and the few remaining large-scale commercial farmers. It is in this context that the potential of the new agrarian structure to sustainably increase Irish potato production was investigated. Increasing potato production on a sustainable basis will enable the crop to assert itself as a national strategic food security crop and help ease the food security challenges the country is grappling with. A grower survey was conducted on the cultural practices, input use, average yield, and infrastructure for potato production. The survey data was used to categorise the growers. Only growers with a minimum 5 years continuous potato growing experience were targeted making the data collected dependable. Grower resource footprints of land, water, biocides and nutrients were calculated based on the actual yield, Ya. Further, the Ya data collected were used to calculate the yield gap, YG, based on the yield of the best performing growers, Yh, simulated yield potential, Yp, and water-limited potential yield, Yw, of the respective agro-ecological areas. The LINTUL-POTATO model was used to estimate Yp, Yw and water need. This model simulates potential dry matter production based on radiation use efficiency of intercepted light by the potato crop. Another model, the Cool Farm Tool-Potato was used to further distinguish and appraise the production systems in terms of yields, inputs and efficient use of energy as reflected in their CO2 balances. The model calculates the contributions of various production operations to the total greenhouse gas (GHG) emission. Consequently, grower practices which contribute the most to the GHG emission were identified and generic mitigation measures for each production system were suggested. Realising the growing importance of sustainability issues in agricultural production and the scarcity of evaluation protocols in cropping systems, the study developed a framework that can be used to evaluate cropping systems. The framework was constructed using the potato-based cropping systems in the Eastern Highlands of Zimbabwe. Finally, instead of just focusing on the production related aspects only, the study also took into cognisance the need to understand the performance of the entire Irish potato sector in Zimbabwe. A value-chain analysis was therefore conducted to evaluate the performance the Irish potato sector in the country. Irish potato production in Zimbabwe is still low. Experts estimate annual production at nearly 120,000 t from around 6,000 ha. The large-scale commercial and the A2 resettlement are large-scale, high input and mechanised systems with an average potato area of 9 ha per planting. The communal area and A1 resettlement are smallholder low input systems with average potato area per planting of 0.8 ha and animal-drawn equipment is used. On resource use efficiencies, the actual tuber yield ranged from 8 – 35 t/ha across all systems representing a yield gap of over 77 %. Comparing with the simulated average potential yield, the mean actual yield observed ranged from 8 to 35 % of the simulated potential yield, translating to a yield gap of 65 to 92 %. Hence there is a large potential to increase potato production in these environments. The nutrient use efficiencies range were: 97 to 162 g potato g-1 N, 93–105 g potato g-1 P2O5 and 97–123 g potato g-1 K2O. This was anticipated because of the high synthetic fertiliser use and the low actual yields reported. The biocide use efficiencies ranged from 0.5 to 0.9 kg potato g-1 active ingredient (a.i.) fungicide, and 8 to 15 kg potato g-1 a.i. insecticide. Regarding water use, the average water use efficiency based on irrigation water and rainfall, ranged from 2 to 6 g potato l-1, while the simulated potential water use efficiency from irrigation and precipitation ranged from 9 to 17 g potato l-1. The large gap observed between actual and potential water use efficiency shows the scope to improve crop management practices to increase actual yield while lowering irrigation water. On the CO2 balance of the systems, a high carbon footprint was reported with an average of 251 kg CO2 eq./t potato. The least average carbon footprint was 216 kg CO2 eq./t potato for the communal area, while the A2 resettlement system had the highest of 286 kg CO2 eq./t potato. The high carbon footprint was anticipated as a reflection of the systems’ inefficiencies in terms of low yields and high input use. Focussing on the performance of the entire Irish potato sector, value chain analysis showed considerable levels of value-addition and gross profit of at least 13 % at each linkage. While the sector enjoys government policy support, major factors impacting on the value-chain performance relate to high potato production costs, low yields, and lack of farmer training. On the proposed framework on cropping sustainability, the indicator thresholds serve to monitor farmer progress as they improve their practices towards the desired direction of sustainability. This study demonstrated that there is tremendous potential to increase potato output and help ease the food insecurity challenges the country currently faces.