On-farm Field Experiments Research Articles

Combined Application of Biofertilizers and Inorganic Nutrients Improves Sweet Potato Yields.

Sweet potato [Ipomoea batatas (L) Lam] yields currently stand at 4.5 t ha−1 on smallholder farms in Uganda, despite the attainable yield (45–48 t ha−1) of NASPOT 11 cultivar comparable to the potential yield (45 t ha−1) in sub-Saharan Africa (SSA). On-farm field experiments were conducted for two seasons in the Mt Elgon High Farmlands and Lake Victoria Crescent agro-ecological zones in Uganda to determine the potential of biofertilizers, specifically arbuscular mycorrhizal fungi (AMF), to increase sweet potato yields (NASPOT 11 cultivar). Two kinds of biofertilizers were compared to different rates of phosphorus (P) fertilizer when applied with or without nitrogen (N) and potassium (K). The sweet potato response to treatments was variable across sites (soil types) and seasons, and significant tuber yield increase (p < 0.05) was promoted by biofertilizer and NPK treatments during the short-rain season in the Ferralsol. Tuber yields ranged from 12.8 to 20.1 t ha−1 in the Rhodic Nitisol (sandy-clay) compared to 7.6 to 14.9 t ha−1 in the Ferralsol (sandy-loam) during the same season. Root colonization was greater in the short-rain season compared to the long-rain season. Biofertilizers combined with N and K realized higher biomass and tuber yield than biofertilizers alone during the short-rain season indicating the need for starter nutrients for hyphal growth and root colonization of AMF. In this study, N0.25PK (34.6 t ha−1) and N0.5PK (32.9 t ha−1) resulted in the highest yield during the long and the short-rain season, respectively, but there was still a yield gap of 11.9 and 13.6 t ha−1 for the cultivar. Therefore, a combination of 90 kg N ha−1 and 100 kg K ha−1 with either 15 or 30 kg P ha−1 can increase sweet potato yield from 4.5 to >30 t ha−1. The results also show that to realize significance of AMF in nutrient depleted soils, starter nutrients should be included.

Comparative Study on Productivity and Profitability of Rice(Oryza SativaL.) Under Different Crop Establishment Methods in Amabala, Haryana

Rice-wheat cropping system is the pre-dominant cropping system in Haryana (India). The continued adoption of exhaustive puddled transplanted rice method has resulted in declined factor productivity. Direct Seeded Rice (DSR) is a promising resource conservation technology in rice-wheat cropping system. Several on-farm and on-station field experiments were conducted during the year 2014 and 2015 to evaluate direct seeded rice options as compared to transplanted rice with an objective to improve farm productivity, efficiency and economics. Labour and cost saving of 97% and 81% were observed in direct seeded rice (DSR) as compared to manual puddled transplanted rice in sowing/transplanting. Manual puddle transplanted (CT-PTR) was found non-significant effect on rice yields compared to Direct seeded rice (DSRv) in vatter during both the years. DSRv and DSRz consumed 18–26% less water as compared to puddled transplanted rice during both years. When compared to manual puddled transplanted rice, a labour saving of 9–13 percent (overall) was observed in both DSR during both the years. The B: C ratio was highest in DSR in zero till condition (4.0) as compared to CT-PTR (3.5), whereas, energy productivity obtained significantly highest in DSR both conditions than CT-PTR during the both years.

Decomposing maize yield gaps differentiates entry points for intensification in the rainfed mid-hills of Nepal

The central mid-hills region of Nepal is characterized by rainfed production systems where maize (Zea mays) is the principal crop during the monsoon (kharif) season. In general, maize yields in the hills are judged to be intractably low and few efforts have systematically assessed either the water-limited productivity potential or identified sensible entry points toward sustainable intensification that can be selectively matched to the needs and constraints faced by different types of farmers. This study combines field surveys, on-farm field experiments, and simulation modeling (DSSAT) to explore opportunities for closing maize yield gaps in these ecologies. Among surveyed households, the mean grain yield of maize under current farmer practice was 2.0tha−1 whereas good agronomic practices increased maize yields up to 6.5tha−1 (i.e. exploitable yield gap of 4.5tha−1). Recognizing that farmers rarely adopt full technology packages, the value of single agronomic interventions was also explored with all other management factors maintained as per prevailing farmer practice. Averaged across sites and two seasons, non-limiting fertilizer rates (175:60:60kgNPKha−1) increased grain yields by 1.8tha−1 followed by the use of hybrids (1.4tha−1), higher plant population (0.9tha−1), and improved weed control (0.9tha−1). These results were also reflected in changes to the economic performance of the system with gross margins increasing from a ‘farmer practice’ base of $202ha−1 (B:C=1.86) to $339ha−1 (B:C=2.14) with hybrid adoption, $454ha−1 (B:C=2.88) with higher plant population, $646ha−1 (B:C=2.52) with non-limiting fertilizer, and $611ha−1 (B:C=3.37) with careful weed control. Further gains in profitability were achieved with layered agronomic interventions, which increased gross margins to $857 and $763ha−1 (B:C=2.95 in both) in conventional tillage (CT) and minimum (strip tillage; ST) systems, respectively. Divergence between grain yield gains and economic performance criteria highlights the importance of considering both perspectives. For resource-poor households, maintaining optimal plant population can increase B:C by more than 50% with small investments ($7ha−1). Simulation results also suggest that additional potential productivity advantages are achievable with timely planting (e.g. 19% higher mean yield for short duration hybrid with less inter-annual variability). Cultivation of longer duration hybrids can also increase yield potential over their shorter duration alternatives, although trade-offs with yield potential of the second crop in the rotation must be considered. These results highlight several pathways toward intensification in the hills of Nepal that have varying investment requirements, inferred risks, and implications for the different dimensions of sustainability and food security.

Rainwater harvesting and conservation tillage increase maize yields in South Africa

Poverty and food insecurity are common amongst rural communities in the sub-Saharan African region. The rural population of South Africa is not excluded from poverty. With normal conventional tillage practices, crop failures are common on marginal soils in semi-arid areas with low and erratic rainfall. Therefore, selected rural communities in the Eastern Cape, Limpopo and Free State Provinces of South Africa were introduced to appropriate rainwater harvesting and conservation agricultural techniques to contribute towards the reduction of food insecurity through improved maize yields. Conventional tillage, no-till, minimum tillage, mechanized basins, in-field rainwater harvesting and the Daling plough were tested in on-station and on-farm field experiments over three to five maize growing seasons (2008/09–2011/13). The rainwater harvesting (in-field rainwater harvesting and Daling plough) and conservation (mechanized basins, no-till and minimum tillage) techniques resulted in slightly higher yields than conventional tillage due to their potential to conserve rainwater better and to harvest additional rainwater. Conventional tillage, no-till and minimum tillage had lower grain yields because they lost on average 18% of the total rainfall to ex-field runoff. The rainwater productivity of the Daling plough treatment was very similar to that of in-field rainwater harvesting, followed by mechanized basins, conventional tillage and no-till or minimum tillage.

EFFECT OF RAISED BED PLANTING TECHNOLOGY ON PRODUCTIVITY, MACRO NUTRIENTS UPTAKE OF BREAD WHEAT AND SAVING IRRIGATION WATER

On-farm field experiments were conducted to assess the effects ofplanting methods (raised bed and farmer practices) on yield and macronutrients uptake of bread wheat, as well as amount of applied water. Thelocations of the experiments were in ten farmers' field representing tendistricts at Al- Sharkia Governorate, Egypt, durinig 2011/2012 and2012/2013 seasons.The obtained results could be summarized as follows:1-Sowing wheat on raised bed was superior in its productivitycompared with farmer practices (traditional sowing) at all locationsunder study in both seasons. The relative increase of wheatproductivity for raised bed were 23.21, 24.70 and 23.98% for grain,straw and biological yield, respectively in the 1st season, as well as34.63, 32.99 and 33.78% for grain, straw and biological yield, inthe 2nd season, respectively.2-Raised bed treatment gave the highest values of nitrogen,phosphorus and potassium uptake for grain, straw and biologicalwheat yield compared to farmer practices in both seasons. Therelative increase of N uptake for wheat grown on raised bed were38.85, 52.22 and 41.41% in the 1st season, as well as 49.28, 50.99and 41.19 % in the 2nd season for grain, straw and biological yield,respectively. The relative increase of phosphorus uptake for wheatgrown on raised bed were 24.23, 24.90 and 24.48 % in the 1stseason and 34.41, 39.53 and 36.39 % in the 2nd season for grain,straw and biological yield, respectively in the 2nd season. Therelative increase of K uptake for wheat grown on raised bed was59.00, 47.87 and 50.08 % in the 1st season, as well as 36.53, 40.59and 39.82% in the 2nd season for grain, straw and biological yield,respectively.3-Raised bed treatment gave the higher saving in irrigation watermore than the farmer practices treatment in both seasons. Theapplied water for wheat sowing on raised bed was lower than flattreatment by 1356 and 1212 m3 ha-1 with savings of irrigation waterby 24.1 and 23.7% in the first and second season, respectively.

Break-crop effects on wheat production across soils and seasons in a semi-arid environment

In low-rainfall environments, a high frequency of cereal crops has been favoured for optimising productivity and risk. However, cereals at high intensity often lead to declining water-use efficiency and increasing inputs to cope with emergent nutritional, disease and weed problems. The value of including breaks in the cropping sequence can involve a high level of uncertainty in low-rainfall areas where non-cereal crops are more risky and profitability is largely determined by the subsequent benefit to cereal productivity. In this study, we aimed to improve understanding of the magnitude and primary source of break benefits such as nutrition, water and disease management in a low-rainfall environment where a high level of within-field soil variability can also contribute to uncertainty about the value of breaks. In on-farm field experiments near Karoonda in the South Australian Mallee, breaks were grown in 2009 or 2010 on four distinct soil types across a dune–swale catena. The effect of these breaks on subsequent cereal production was measured for up to 3 years. In addition, the effect of breaks on nutrition and water available, along with disease infection in subsequent cereal crops, was explored and actual yields were compared with nitrogen and water-limited potential yields. Consistent cumulative benefits to subsequent cereal crops of at least 1 t ha–1 after 3 years accrue from breaks grown on the different soil types. The inclusion of breaks had beneficial effects on the cycling and supply of nutrients along with some short-term impacts on infection by Rhizoctonia solani AG8 in subsequent cereals, whereas there were no conclusive effects of breaks on the supply of water to subsequent crops. This study suggests that the inclusion of both legume and brassica breaks is likely to be beneficial to subsequent cereal production where nitrogen is a factor limiting productivity in low-rainfall, semi-arid environments.

Effects of Mineral Nitrogen and Phosphorus Fertilizers on Yield and Nutrient Utilization of Bread Wheat (Tritcum aestivum) on the Sandy Soils of Hawzen District, Northern Ethiopia

On-farm field experiments were conducted to assess the effects of nitrogen (N) and phosphorus (P) on yield, yield components, nutrients uptake and use efficiencies, protein content of bread wheat, residual soil nitrogen and phosphorus availability and economic return of fertilizer application. The locations of the experiments were in two nearby farmers' field at Hawzen district, Northern Ethiopia. Factorial combinations of five N levels (0, 46, 69, 92 and 138 kg N/ha) and four levels of P (0, 46, 69 and 92 kg P2O5/ha) were laid out in a randomized complete block design with three replications. Experimental Field 1 was relatively better in its soil fertility than experimental Field 2 especially in its phosphorus availability and cation exchange capacity (CEC). However, both fields were low in their total soil nitrogen content. Grain yield of wheat significantly increased by 46% and 15% in Field 1 and Field 2, respectively at nitrogen application rate of 46 kg N/ha than the control. Nitrogen fertilization increased straw yield significantly only in experimental Field 1. Phosphorus application at a rate of 46 kg P2O5/ha increased significantly grain and straw yields by 38 % and 46 %, respectively in Field 2 than control. It is also economical to apply phosphorus at this rate for such farmers’ field because the grain yield marginal rate of return was 179 %. Consistent results were observed on wheat nutrient uptakes and nutrient use efficiencies. Grain and straw yields of wheat were not significantly affected by the main effect of phosphorus application in Field 1. These results are consistent with the soil analysis result before planting where the soil phosphorus was found to be low in Field 1 and very low in Field 2. Previous management by the farmers may have influenced the soil fertility status. There were no interaction effects of nitrogen and phosphorus to affect wheat productivity and nutrient utilization in both fields. Future approach to soil fertility management should consider the past management history and should also be site specific based on soil fertility assessment. As a result, a combined application of 46 kg N/ha and 46 kg P2O5/ha are recommended to achieve sustainable bread wheat production on the sandy soils of Hawzen district. But in fields with higher initial soil phosphorus level, there is no need of applying phosphate fertilizer.

Rhagoletis cerasi: Oviposition Reduction Effects of Oil Products.

The European cherry fruit fly, Rhagoletis cerasi (L.) (Diptera: Tephritidae), is a highly destructive pest. Methods to control it are limited and alternatives are needed. Observations of cherry fruit flies suggest that females exert much effort to penetrate cherries at color change stage (from green to yellow) for oviposition. Therefore, the question arose as to whether a physical barrier on the fruit surface could reduce oviposition. The effects of different commercial horticultural oil products on R. cerasi oviposition were evaluated in a series of laboratory, semi-field and field experiments. In the laboratory experiments, the rate of successful oviposition on fruits treated with 0.25% v/v of the rapeseed oil product Telmion was significantly reduced by 90% compared to the untreated control. In semi-field experiments, deposits of 1% of rapeseed, mineral and paraffinic oil significantly reduced oviposition for up to 3 days. Semi-field experiments indicated that the oil products lose efficacy within 3 to 6 days after application due to degradation. Although treatments with the rapeseed oil product Telmion reduced infestation rates in an on-farm field experiment, the infested fruit clearly exceeded the level of market tolerance of 2%. Further research is needed to assess whether combinations of oil products, higher application rates and different formulations might improve field efficacy.

Fertilizer recommendation for maize in China based on yield response and agronomic efficiency

A generic but flexible and location-specific fertilizer recommendation method is necessary due to inappropriate fertilization in China. A new fertilizer recommendation method, Nutrient Expert (NE) for Hybrid Maize, was developed using maize datasets from 2000 to 2010 in main maize production areas. The results showed that the average of indigenous nutrient supply were 130, 41 and 124kg/ha, the mean of yield response were 2.1, 1.2, and 1.2t/ha, and the average agronomic efficiency were 11.4, 15.7, and 11.8kg/kg for N, P, and K, respectively. There was a significantly negative exponential relationship between yield response and indigenous nutrient supply, and a significant negative linear relationship between yield response and relative yield. Analysis also indicated that the quadratic curve relation was obvious between yield response and agronomic efficiency. NE system was established based on yield response and agronomic efficiency (AE) through above analysis, and on-farm field experiments were conducted in 408 farmers’ fields to validate this system at seven provinces in China. The results showed that fertilizer recommendation based on NE method could maintain grain yield and profitability and improve nutrient use efficiency through 4R nutrient stewardship and it is proved to be a promising approach for fertilizer recommendation when soil testing is not timely or not available.

EVALUATION OF SLOPING AGRICUL TURAL LAND TECHNOLOGY (SALT) AS A MEANS OF ENSURING S.USU'.INABILITY OF TEA YIELDS IN THE UP-COUNTRY WET ZONE (WU2) OF SRI LANKA

Sloping Agricultural Land Technology (SACT) is a system of land management that hasbeen introduced to arrest the decline of soil fertility and sustain yields of tea plantations 0[1sloping terrain in the central highlands of Sri Lanka. SALT involves the incorporation offast-grov.ing, mostly leguminous tree species as hedgerows along contours atpre-determined distances among tea rows. The hedgerows are expected to increase soilfertility by reducing erosion and providing organic matter through frequent addition ofprunings. However, SALT hedges could compete with tea for essential growth resourcessuch as water, nutrient and light and consequently reduce tea yields. Therefore, the mainobjective of this study was to quantify the positive ana negative effects of SALT hedges andto determine their net impact on tea yields and parameters of soil fertility.Two long-term, on-farm field experiments were conducted at Helbodde Estate, Pussellawain the Up-Country Wet Zone (WU2) The effects of six tree species (Calliandracalothyrsus, Cassia spectabilis, Euphatoriun: innulifolium, Flemingia congesta, Gliricidiaseptum aid Tithonia diversifolia) growing as contour hedgerows on the long-term yields ofmature tea (ie. in the second pruning cycle) and young tea (i.e. first pruning cycle) werequantified in Experiments 1 and 2 respectively. These experiments also measured the yieldresponse to the addition of mulch material from different tree species. Continuous yieldmeasurements were done at weekly intervals since November 1998.Continuous tea yield measurements that were done at weekly intervals were compiled andanalyzed over a three-year pruning cycle from November 1998 to October, 200 1. InExperirne nt I, yield of mature tea growing with Euphatorium hedgerows was significantlygreater than the yield of tea growing without hedgerows (i.e, control plots). However,yields of .nature tea growing with all other hedgerow species were significantly lower than111 the cor.trol. Mature tea yields of all hedgerow plots increased significantly in response tothe addition of the respective hedgerow prunings as mulch. These results show thatalthough all hedgerow species contribute to the improvement of soil fertility, all hedgerowspecies except Euphatorium exert significant resource competition, whieh exceeds theirrespective positive fertility effects. In Experiment 2, yields of young tea growing with allhedgerow species, including Euphatorium showed significant reductions as compared tothe yield of sole cropped young tea. This shows that young tea is less able to withstandresource competition from hedgerows than mature tea. However, in Experiment 2, the leastyield rediction was shown in tea growing with Euphatorium. Among the differenthedgerow tree species tested, Euphatorium showed the highest yield increase due to theaddition cf prunings as mulch in both' experiments.There was significant variation in the biomass production between different hedgerow treespecies in both experiments. Calliandra and Cassia produced greater biomass than the restwhile Glir'cidia and Euphatorium produced lower biomass levels. In both experiments,there were moderately strong negative relationships between tea yield and hedgerowbiomass. This is a confirmation that higher biomass production by the hedgerows increasestheir resource u~e and decreases tea yields.Detailed analysis of soil chemical and physical properties showed significant variationbetween S/,L T systems with different hedgerow species and between mulching treatments.In mature lea, the soil N, P and K contents were lower in SALT plots than in sole leacrops. In young tea, while most of the SALT plots had higher soil N than the control, bothP and K in SALT plots were lower than in the control. In both mature and young tea, soilCa was lower in SALT systems than in the control- In contrast, soil Mg in the majority ofSALT plots was lower than the control in mature tea while the opposite was observed inyoung tea. !n both mature and young tea, the majority of SALT systems had a lower soilpH than the control plots. However, the SALT systems of both mature and young tea had ahigher soil cation exchange capacity (C~C) and organic matter (OM) content than therespective sole tea crops. In SALT plots with both mature and young tea, mulchingsignificantly increased soil N, P, K, Ca, Mg, CEC and OM. However, soil pH did notchange sigr ificantIy due to mulching. Multiple regression' analysis showed that 87% of theobserved yield variation of mature tea in SALT systems could be explained by the variationof the above soil properties. In SALT systems with young tea, 98% of the yield variationcould be explained by the variation of soil properties.Based on the above results of these two long-term experiments, it is concluded thatincorporatic n of tree hedges in existing tea fields have to be done with caution as it coulddecrease tea yields due to excessive resource competition. However, SALT systems showedsome positive indicators such as greater soil organic matter and cation exchange capacity,which may contribute to long-term increase of soil fertility and sustainability of tea yieldson sloping terrain in the central highlands of Sri Lanka.

Optimizing Nitrogen Fertilizer Application for Rice Production in the Taihu Lake Region, China

To determine the optimal amount of nitrogen (N) fertilizer for achieving a sustainable rice production at the Taihu Lake region of China, two-year on-farm field experiments were performed at four sites using various N application rates. The results showed that 22%–30% of the applied N was recovered in crop and 7%–31% in soils at the rates of 100–350 kg N ha −1. Nitrogen losses increased with N application rates, from 44% of the applied fertilizer N at the rate of 100 kg N ha −1 to 69% of the N applied at 350 kg N ha −1. Ammonia volatilization and apparent denitrification were the main pathways of N losses. The N application rate of 300 kg N ha −1, which is commonly used by local farmers in the study region, was found to lead to a significant reduction in economic and environmental efficiency. Considering the cost for mitigating environmental pollution and the maximum net economic income, an application rate of 100–150 kg N ha −1 would be recommended. This recommended N application rate could greatly reduce N loss from 199 kg N ha −1 occurring at the N application rate of 300 kg N ha −1 to 80–110 kg N ha −1, with the rice grain yield still reaching 7 300–8 300 kg DW ha −1 in the meantime.

Alfalfa Responses to Combined Use of Lime and Limiting Nutrients on an Acidic Soil

An on-farm field experiment was conducted on an acidic soil to investigate the effects of combined use of lime and deficient nutrients on herbage yield of alfalfa (Medicago sativa L.). Omitting lime and limiting nutrients led to elevated concentrations of aluminium (Al), iron (Fe), and manganese (Mn) in alfalfa leaves and stems and caused severe reductions in herbage yield of alfalfa. Combined use of lime (2 t ha−1) and nutrients [phosphorus (P): 20 kg ha−1, sulfur (S): 20 kg ha−1, zinc (Zn): 4 kg ha−1, and boron (B): 2 kg ha−1] had the maximum increase in groundcover, root biomass, nodulation, leaf retention, leaf-to-stem ratio, herbage yield, crude protein, and nutrient composition of alfalfa. These beneficial effects were due to raised soil pH; improved calcium (Ca), P, S, Zn, and B nutrition; and reduced Al, Mn, and Fe toxicity. Aluminium and all the nutrients except copper (Cu) were more concentrated in alfalfa leaves than stems. Aluminum concentration was about three times greater in the lower leaves than in upper leaves. Lower leaves also had much greater concentrations of Ca, Mg, K, S, Fe, Mn, Cu, and B compared with upper leaves. In contrast, P and Zn concentrations were greater in the upper leaves than in lower leaves. Results suggest that the combined use of lime and all the limiting nutrients may realize potential beneficial effects of alfalfa on acidic soils where more than one essential nutrient is deficient. This may increase growth potential, nitrogen contributions, and groundcover by alfalfa and reduce soil erosion and runoff.

Field assessment of novaluron for sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), management in Louisiana sugarcane

On-farm field experiments were conducted in 2004 and 2007 to assess the suitability of novaluron, a chitin synthesis inhibitor, for sugarcane borer, Diatraea saccharalis (F.), management in Louisiana sugarcane ( Saccharum spp. hybrids). Aerial insecticide applications reproducing commercial production practices were made when D. saccharalis infestation levels exceeded a recommended action threshold. In addition to decreased D. saccharalis infestations, 6.3 – 14.5-fold reductions in end of season injury, expressed as the percentage of bored sugarcane internodes, were observed in plots treated with novaluron. D. saccharalis control in novaluron plots was equivalent to ( P > 0.05) or better ( P < 0.05) than that achieved with tebufenozide, an ecdysone agonist that has been extensively used for over a decade on sugarcane. With a numerical trend of a 3.1-fold decrease in percent bored internodes, the pyrethroid gamma-cyhalothrin seemed less effective than the biorational insecticides in protecting sugarcane against D. saccharalis. Using continuous pitfall trap sampling, no measurable ( P > 0.05) decreases in predaceous and non-predaceous soil-dwelling non-target arthropods were associated with insecticides. However, numerical trends for decreases in immature crickets associated with novaluron and gamma-cyhalothrin were recorded in 2007. Our data suggest that novaluron will fit well in Louisiana sugarcane integrated pest management.

Potential of plastic barriers to control Andean potato weevil Premnotrypes suturicallus Kuschel

In potato production systems of the high Andes, Andean potato weevils of the genus Premnotrypes and Rhigopsidius are the most important potato pests. The adults are flightless insects that migrate to potato fields during the potato-growing season, where the larvae damage a high proportion of the tuber harvest. We tested the hypothesis that plastic barriers established at field borders at sowing time are effective management tools to stop Andean potato weevil migration into potato fields, with a consequent reduction in Andean potato weevil tuber damage. In addition, we studied the effect of barriers on carabids, which represent an important insect family in the Andes and are natural enemies of Andean potato weevils. The studies were carried out in 21 on-farm experiments in two villages in the Central Highlands of Peru. The effect of plastic barriers was compared to farmers' practice, consisting of 1–4 insecticide applications per potato-growing season, in participatory research in fallow–potato and potato–potato rotation systems in which the Andean potato weevil Premnotrypes suturicallus Kuschel is endemic. Plastic barriers proved to be highly effective in stopping weevil migration. In screen house experiments only a small proportion (13%) of weevils was able to escape from plastic heights of 25 cm. A height of 50 cm could not be overcome, which was the height used in the on-farm field experiments. The combination of plastic barriers with pitfall traps installed close to the plastic significantly increased the number of Andean potato weevil catches, and proved an effective technology for mass trapping of Andean potato weevil adults. Plastic barriers also affected and increased the number of carabids, mainly of the genus Blennidus, in the pitfall traps. The proportion of carabids was 4–5 times higher in the location in which a lower number of Andean potato weevils and damaged tubers were observed. The results suggest that carabids are important predators of Andean potato weevils. The plastic barriers effectively reduced Andean potato weevils-caused potato tuber damage at harvest. Compared to the farmers' practice of using insecticides, the barriers were equally effective in fallow–potato rotation systems. In potato–potato rotation systems the combination of plastic barrier with one application of insecticide was superior to farmers' practice using 3–4 insecticide applications. The costs for plastic barriers were calculated to be equivalent to two or three insecticide applications per hectare. Plastic barriers are proposed as a new effective component for Integrated Pest Management of Andean potato weevils.

Effect of Rhizobium–Azospirillum coinoculation on nitrogen fixation and yield of two contrasting Phaseolus vulgaris L. genotypes cultivated across different environments in Cuba

Azospirillum spp. have shown potential to enhance nodulation and plant growth of legumes when coinoculated with Rhizobium. The effect of Azospirillum on the Rhizobium-legume symbiosis is, however, dependent on the host genotype used. Previous greenhouse experiments identified two genotypes of common bean (Phaseolus vulgaris L.), BAT477 and DOR364, contrasting in nodulation response to Azospirillum when coinoculated with Rhizobium. Genetic analysis revealed a genetic basis (Quantitative Trait Loci) on the bean genome related to the differential responsiveness to Azospirillum between the two bean genotypes. In this study, on-station and on-farm field experiments in different regions in Cuba were conducted to evaluate the agronomic relevance of the differences in response to Azospirillum–Rhizobium coinoculation between the two genotypes BAT477 and DOR364. It was observed that Azospirillum–Rhizobium coinoculation as compared to single Rhizobium inoculation increased the amount of fixed nitrogen and the yield of DOR364 across all sites. For BAT477, on the contrary, a negative effect of Azospirillum–Rhizobium coinoculation on yield and nitrogen fixation was observed on most of the sites as compared to single Rhizobium inoculation. The modified stability regression equations resulting from this study may contribute to predict how a combination of genotype and inoculum will perform at a certain environmental setting. This study highlights the importance of genotype × inocula interactions in agricultural outputs and establishes a link between greenhouse phenotype, genetic background and performance in the field.

Evaluation of application timing in fertilizer micro-dosing technology on millet production in Niger, West Africa

Micro-dosing technology has been developed by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and its partners to help subsistence farmers in the Sahel improve inorganic fertilizer application. However, the ICRISAT's recommendations regarding fertilizer application through this technology are only applicable at sowing and do not allow any flexibility in terms of labor and/or capital management. In rural areas, fertilizer cannot always be applied at sowing due to financial and labor constraints. The purpose of this study was to evaluate the effect of the timing of fertilizer application on millet production. A 2-year on-station experiment and a 1-year on-farm field experiment were conducted in the western region of Niger, West Africa. Even under the heterogeneous climatic conditions of the region during our experimental period, the results showed that the trend was the same as observed in previous studies: millet production improved through fertilizer application compared to the control (without fertilizer). The harvest index was also higher compared to that of the control. This increased production was consistently the same for all application timings. The marginal value–cost ratio on the investment calculated using a budgeting analysis for the on-farm experiment showed that – regardless of application timing – millet farmers who fertilized their fields with inorganic fertilizer made more profit than those who did not (control). This was also true for farmers who were unable to fertilize at sowing – delayed application was still the more profitable option relative to the no fertilizer control. Our results indicate that small subsistence farmers can be offered more options for inorganic fertilizer application timing using the micro-dosing technology. Delayed inorganic fertilizer application can help small farmers who are often labor constrained at the sowing period improve their yields as well as their economic returns.

On-farm seed priming for barley on normal, saline and saline–sodic soils in North West Frontier Province, Pakistan

“On-farm” seed priming (soaking seeds in water prior to sowing) has been shown effective in producing earlier germination, better establishment and increased yields in a range of crops in many diverse environments. We carried out microplot, on-station and on-farm field experiments and participatory trials in several environments, including saline, saline–sodic and normal (non-saline, non-sodic) soils, in the North West Frontier Province (NWFP) of Pakistan over a number of years to assess the effect of priming on barley yields. In general, priming was found to increase yields of both grain and straw (an important product in NWFP agriculture). Grain yield increases due to priming were up to 53% in the participatory trials. Optimum duration of priming was between 12 and 16 h, and the response to priming was better in low potential environments than under better conditions. Priming was also more advantageous on saline–sodic than on saline soils, possibly as a result of the water content of the soil. It was concluded that “on-farm” priming of barley could be recommended to farmers in NWFP and in similar environments in other parts of the world who produce barley both for grain and for fodder.

EFFECT OF VARYING MAIZE DENSITIES ON INTERCROPPED MAIZE AND SOYBEAN IN NEPAL

Maize and soybean are commonly intercropped in the drier zones of the western mid-hills in Nepal, but farmers report that productivity of soybean has been declining in recent years. Two researcher managed on-farm field experiments were conducted in the mid-hills environment of Nepal during 2001 and 2002, and one glasshouse experiment at the University of Wales, Bangor during 2003, to determine whether varying densities of maize and soybean influenced productivity of the system and to what extent soybean exhibited adaptation to shade. In neither season was maize yield affected by the presence of soybean, but grain yield of soybean was reduced in mixture by means of 59 and 53% during 2001 and 2002 respectively. Biomass and grain yield of maize were greatest at 53×103 plants ha−1 and least at the lowest density, whilst conversely biomass and grain yield of soybean increased. With increasing maize density, rates of accumulation of dry matter and leaf area index also increased, the latter resulting in decreasing transmission of light to the intercropped soybean. Soybean exhibited no photosynthetic adaptation to shade, but the specific leaf area was greater in artificially shaded and intercropped plants. Land equivalent ratios of all intercrops were greater than unity (1.30 to 1.45), indicating higher efficiency of intercropping compared to sole crops. Given the low plasticity in response of the maize canopy to variations in density, it is suggested that soybean could be better grown under maize by increasing between-row spacing of maize from 0.75 to 1.0 m to improve light transmission to the understorey, resulting in higher overall productivity of the intercropping system, and also that soybean germplasm be screened for adaptation to shade.

Comparing Hemp Seed Yields (Cannabis sativaL.) of an On-Farm Scientific Field Experiment to an On-Farm Agronomic Evaluation Under Organic Growing Conditions in Lower Austria

Abstract Hemp seed yields of the variety Fedora-19 in an on-farm scientific field experiment on small plots and in an on-farm evaluation in 11 hemp fields under practical organic growing conditions in Lower Austria were compared to give a realistic view of the variability of yields. Dry matter seed yields from the on-farm field experiment ranged from 127 to 143 g m−2. Under practical growing conditions, yields ranged from 34 to 151 g m−2 in the sample plots. The reported hemp seed yield after combine harvesting, drying, and cleaning was between 324 kg ha−1 and 717 kg ha−1. The results of the experiment show that harvesting by hand considerably influences yields. Yields of the manual harvest in sample plots indicate a high correlation with yields harvested by the combine harvester (R2 = 0.91). The commercial yield is 71% of the yields recorded in sample plots in the fields. Our data questions the transfer of results and conclusions drawn from the data of scientific field experiments that employ manual harv...

Productivity and economic of on-farm rainfed rabi crops in rice based croping system under different moisture conservation practies

On-farm field experiments were carried out in midland rainfed rice based cropping system during rabi seasons of 1999-00 and 2000-01 at village Khatti, district Mahasamund (C.G.) under National Agricultural Technology Project, RRPS-3 to explore the possibility of rabi crops (Safflower, Gram, Lentil, Lathyrus and Greengram) using moisture conservation practices (no mulch, soil and stubble mulch and rice straw mulch) in rainfed rice area. Among the crops, safflower produced significantly higher gram equivalent yield (13.50 q ha') and net profit (Rs. 10142 ha) than that of gram during 1999-00, while it was at par during 2000-01. Among the mulches, application of rice straw mulch recorded significantly higher grain yield (6.49 q ha¹) and net return (Rs. 10142 ha) and it was on par with that of soil and stubble mulch. Regarding interaction effect safflower with rice straw mulch gave significantly higher grain yield (12.29 q ha¹), which was at par with that of soil stubble mulch.