Reduction In Application Rate Research Articles

Effect of Spray Adjuvant and Prohexadione Calcium Formulation on Peanut (Arachis hypogaea L.) Productivity

Prohexadione calcium (calcium 3-oxido-5-oxo-4-propionylcyclohex-3-enecarboxylate) is used to manage excessive vegetative growth in peanut (Arachis hypogaea L.). This practice has traditionally been more widespread in Virginia market-type cultivars that generally have more vigorous canopy growth. However, the use of this active ingredient in runner peanut cultivation continues to increase. Prohexadione calcium was initially formulated as a water dispersible granule (WDG) and a new oil dispersion (OD) formulation has been introduced. Limited information is available regarding optimal adjuvants and application rates for the OD formulation of prohexadione calcium. This study aims to assess the efficacy of the new OD formulation of prohexadione calcium on pod yield, grade and economic return. Six experiments were conducted across locations in Mississippi and Georgia in 2022. The findings indicate that the OD formulation yields similar effects in managing excessive vine growth when using either crop oil concentrate or non-ionic surfactant adjuvants, thereby resulting in comparable yield, grade, and economic return to that of the WDG formulation. Moreover, prohexadione calcium exhibits the capacity to suppress excessive vegetative growth and enhance pod yield at reduced application rates, specifically at105 g ai/ha. This reduction in application rate, coupled with the improvement in yield, translated into a higher return on investment, ranging from 30 to 400 U.S. dollars per hectare, across three out of four experimental sites when compared to the non-treated control. These results suggest that profitability could be increased by applying prohexadione calcium on runner peanuts if excessive vine growth occurs.

Preciseness, rather than simplicity, is required to assess pesticide reduction strategies: Findings from rice production in Japan

Pesticide reduction is given high priority in the worldwide sustainability agenda. The reduction of pesticide impacts, rather than the reduction of application rates, has become a common criterion for monitoring policy progress. However, simplicity—an essential requirement in improving the applicability of pesticide impact assessment—may distort the accuracy of the evaluation and therefore prevent effective pesticide reduction. Here, we present contrasting results that underscore how the selection of evaluation methods that differ in simplicity affects the assessment results of pesticide reduction strategies. Briefly, we analysed the impact of conversion from conventional to low-input management adopting both a simplified linear-based method and a precise method that includes newly calculated nonlinear approach-based characterization factors for 109 active ingredients (AIs). The two methods were then used to estimate the freshwater ecotoxicity impact of eight rice farms in Japan where both conventional pesticide application and pesticide reduction strategies are practiced. The results show that the simplified method generated anomalies at the farm level through overestimation and underestimation of the individual AI impacts. Patterns that contributed to extreme changes of impact at the farm level were also identified. These findings suggest a strong need for a precise evaluation method for effectively monitoring policy progress at the farm level.

Effect of agricultural extension services in the post-reform era since the mid-2000s on pesticide use in China: evidence from rice production

ABSTRACT Pesticide overuse has resulted in serious ecological problems. Agricultural extension services play a key role in influencing farmers’ pesticide use. China has the world's largest public agricultural extension system, which has experienced a twisting path of reforms over the past four decades. However, there is little empirical evidence regarding the effects of agricultural extension services in the post-reform era since the mid-2000s. This study examines the effect of agricultural extension services in the post-reform era on pesticide use in China, using survey data of 1963 rice farmers in 2016 and 2018. Our results indicate that only 22.5% of surveyed farmers adopted agricultural extension services. After addressing the self-selectivity issue, the treatment effects model revealed that agricultural extension services in the post-reform era resulted in a 3.01 kg/ha reduction in total pesticide use, a 0.86 kg/ha reduction in application rate of active ingredients, and a 250 CNY/ha reduction in pesticide expenditure related to rice production. Our findings provide sound evidence that agricultural extension services in the post-reform era can result in a reduction in pesticide use for rice production. More effective efforts should be made to reinforce the provision of agricultural extension services and encourage farmers to adopt these services.

ELECTROSTATIC SPRAYING EFFECT ON SPRAY DEPOSITION AND POWDERY MILDEW CONTROL IN SOYBEAN

ABSTRACT Electrostatic spray can bring benefits to the pesticide application such as the reduction of application rate and the increase of deposits on targets. Therefore, this study aimed to evaluate the effect of electrostatic spraying using lower application rates and different adjuvants on soybean spray deposition and chemical control of powdery mildew (Microsphaera diffusa Cooke & Peck). The field experiment was conducted in duplicate. A randomized complete block design with four replications in a 2 × 2 × 2 + 1 factorial scheme was used. The factors were two application rates, with and without droplet electrification, two spray solution compositions, and one additional treatment. Deposition on upper and lower leaves, spray loss to the soil, and powdery mildew control effectiveness were evaluated. The electrical conductivity of the spray solution and the charge/mass ratio induced in droplets were also evaluated. All treatments reduced the soybean powdery mildew severity. Electrostatic spraying responded positively to an increase in the electrical conductivity of the spray solution regarding the charge/mass ratio, but it did not increase spray deposition on the lower third of the canopy and did not influence spray loss to the soil, which was higher as the application rate increased.

One‐Time Fertilizer Briquettes Application for Maize Production in Savanna Agroecologies of Ghana

Declining maize yields in the Guinea Savanna ecological zone of Ghana call for effective nutrient management strategies that increase maize productivity and profitability among smallholder farmers. Field trials were conducted during 2016 and 2017 in three locations in northern Ghana to evaluate the agronomic effectiveness of one‐time application of multi‐nutrient fertilizer briquettes for maize production. The treatments were: (i) farmer practice (FP); (ii) NPK fertilizer briquettes applied at the recommended N, P, and K rates (100%‐Briquette); (iii) 75%‐Briquette; (iv) modified farmer practice (MFP) with N, P, and K applied at the recommended rate (100%‐MFP); (v) 75%‐MFP; and (vi) control, with no fertilizer applied. The farmer practice involved surface broadcasting the granular N, P, and K fertilizer at the recommended rate. The MFP involved subsurface incorporation of the granular fertilizer into the soil. Across all three locations and in both years, maize grain yield resulting from the treatments followed this order: 100%‐Briquette > 100%‐MFP = 75%‐Briquette > 75%‐MFP > FP > control. Despite the greatest grain yields resulting from the 100%‐Briquette treatment, the greatest gross profit margin of 0.46 was obtained with the 75%‐Briquette treatment, followed by the 100%‐Briquette treatment (∼0.43), 100%‐MFP (∼0.39), 75%‐MFP (∼0.24), and FP (0.03). From the combined results, we conclude that the one‐time application of multi‐nutrient fertilizer briquettes could be an efficient fertilizer management strategy to increase maize yields and profitability for smallholder farmers in the Guinea Savanna zone. This presents a real strategy for improved productivity across diverse agroecologies for food security among smallholder farmers.Core Ideas One‐time application of multi‐nutrient fertilizer briquettes increased maize grain yields. High nutrient recovery efficiency of fertilizer briquettes resulted in a 25% reduction in application rates. Application of fertilizer briquettes resulted in the greatest gross profit margin of 46%. The traditional farmers’ practice of surface broadcast resulted in lowest gross profit margin of only 3%. Incorporation of fertilizers into the soil resulted in an increase of gross profit margin to 39%.

Development of canopy vigour maps using UAV for site-specific management during vineyard spraying process

Site-specific management of crops represents an important improvement in terms of efficiency and efficacy of the different labours, and its implementation has experienced a large development in the last decades, especially for field crops. The particular case of the spray application process for what are called “specialty crops” (vineyard, orchard fruits, citrus, olive trees, etc.) represents one of the most controversial and influential actions directly related with economical, technical, and environmental aspects. This study was conducted with the main objective to find possible correlations between data obtained from remote sensing technology and the actual canopy characteristics. The potential correlation will be the starting point to develop a variable rate application technology based on prescription maps previously developed. An unmanned aerial vehicle (UAV) equipped with a multispectral camera was used to obtain data to build a canopy vigour map of an entire parcel. By applying the specific software DOSAVINA®, the canopy map was then transformed into a practical prescription map, which was uploaded into the dedicated software embedded in the sprayer. Adding to this information precise georeferenced placement of the sprayer, the system was able to modify the working parameters (pressure) in real time in order to follow the prescription map. The results indicate that site-specific management for spray application in vineyards result in a 45% reduction of application rate when compared with conventional spray application. This fact leads to a equivalent reduction of the amount of pesticide when concentration is maintained constant, showing once more that new technologies can help to achieve the goal of the European legislative network of safe use of pesticides.

Summer Fertigation of Dairy Slurry Reduces Soil Nitrate Concentrations and Subsurface Drainage Nitrate Losses Compared to Fall Injection

Leaching of nitrate (NO3-N) from manure-applied cropping systems can represent a substantial N-loss to the environment for dairy farms, particularly in fields with artificial subsurface drainage. In this on-farm study, we used a Before/After analysis to assess the effectiveness of summer fertigation with reduced manure rates (years 2010 – 2015) versus fall injection (2007 – 2009) of dairy slurry in terms of subsequent corn silage yield, corn N removal, soil NO3-N distribution, and NO3-N losses in subsurface tile drainage from a 65-ha field in Minnesota, USA. Yield was similar between periods (average of 18.8 Mg ha-1), but crop %N, N removal, and manurial N-use efficiency were 15, 12, and 126% greater during the fertigation than injection period. Fertigation reduced spring soil NO3-N concentrations to 60-cm depth by an average of 53% relative to injection, except in the 15 to 30 cm increment, where no difference was found. Similarly, fall soil NO3-N concentrations from 30 to 90 cm were 48% lower, on average, under fertigation than injection. Weekly flow-weighted mean NO3-N concentration in tile drainage was lower during fertigation (47.7 mg L-1) than injection (56.8 mg L-1), although mean weekly drainage depth was greater during fertigation (2.3 versus 1.1 mm). This resulted in similar weekly loads between periods (mean of 0.96 kg NO3-N ha-1). For non-snowmelt flow, relationships between drainage and NO3-N load showed log–log slopes of near 1.0 for injection and 0.97 for fertigation, indicating dilution of concentrations with increased flow during fertigation, but not during injection. Differing intercepts indicated a treatment effect of fertigation independent of flow effects, and corresponded to loads of 5.9 kg NO3-N ha-1 for injection and 4.7 kg NO3-N ha-1 for fertigation, a reduction of 20% at a 10 mm weekly flow depth. The magnitude of the reduction in load increased to 22% at a 25 mm weekly flow depth. Results suggest that summer fertigation with attendant reduction in application rate is a viable method for reducing drainage NO3-N losses without impacting yield of irrigated silage corn in the U.S. Midwest.

Projections of Chloride Concentrations in Urban Lakes Receiving Road De-icing Salt

The chloride concentrations of urban lakes where road de-icing salt (NaCl) is used have increased to levels that can change natural lake-mixing behavior and influence aquatic life. A zero-dimensional model was formulated to project the long-term accumulation of chloride in urban lakes receiving runoff from roads on which road salt is applied. Four model parameters and an initial concentration were obtained by calibrating the model with 5 years (2004-2008) of monthly salinity data from seven lakes in the Minneapolis/St. Paul Twin Cities Metropolitan Area of Minnesota, USA. Three of the seven lakes appear headed towards year-round volume averaged chloride concentrations above the 230-mg/L chronic standard for impairment to aquatic habitat. The two lakes with the lowest projected equilibrium concentrations of chloride have already reached equilibrium. One lake is projected to take an additional 40 years to reach equilibrium under current climate conditions and current road salt application rates. If road salt application rates are reduced in future winters, it is projected that the lakes will respond with noticeably lower chloride concentrations within 5 to 10 years. If road salt applications are discontinued altogether, chloride concentrations are projected to drop to natural levels within 10 to 30 years in all seven lakes. A reduction of application rates by 50% would result in annual volumetric average chloride concentrations below the chronic standard.

Variations in insecticide dose received by settled locusts: a computer model for ultra-low-volume spraying

A computer model has been devised to examine the variation in the insecticide dose received by settled locusts resulting from change in the primary application variables [volume and mass application rate, spray drop size distribution, emission height and wind speed (with logarithmic wind profile)], while taking into account formulation differences, i.e. specific gravity and volatility. A buoyancy factor can be incorporated, but has been omitted from most of the present calculations. The size and collection efficiency of the locust target are estimated, and drop collection has been computed as the sum of the contributions of the two component processes, i.e. inertial collection on the vertical projected area and sedimentary collection on the horizontal projected area. The lethal swath is shown to be narrowest at very low wind speeds, when dose is mainly dependent on the sedimentary component of deposition. There is progressive widening of swath forecast for increasing wind speed and emission height, coupled with decreasing drop size, until the increasing dilution limits the realization of the lethal dose level. In addition, fall-off in collection efficiency can place a limit to the lowest effective size. For any wind speed there is shown to be a particular volume median drop diameter which maximizes the lethal swath; however, the downwind displacement of the lethal swath is shown to increase progressively with increasing wind speed, emission height and decreasing drop size. Thus the choice of optimum size depends on a trade-off between these effects and accurate targeting in strong winds requires either (a) an appropriate upwind offset in the line of emission (or decrease in emission height), or alternatively (b) some increase in drop size to limit displacement. For aerial spraying from 10 m height at a flow rate of 151 min −1, a volume median diameter (VMD) ⩽ 120 μm is forecast to justify the recommended 100 m track spacing, but the crosswind velocity component should exceed 2 m s −1. The lethal effect is shown to be lost if the emission height is increased to 20 m, unless there is a compensatory increase in flow rate. The VMD may have to be increased to 180 μm to maintain precision in winds above 5 m s −1 if a low emission height is not feasible; however, if the target bands are diffuse, it may be preferable to retain the advantage of the wider swaths accruing from the smaller VMDs (i.e. large reduction in application rate if allied to wider track spacing), while accepting some accompanying uncertainty in placement.