Development of a sensor-based embedded system for on-the-go variable-rate fertilizer applicator in maize crop

Site-specific farming (SSF) practices are being adopted at an accelerating rate, but evidence of their profitability has been mixed or missing. This contribution evaluates the profitability of SSF practices by synthesizing quantitative and qualitative research results within the context of the economics of information technology. The profitability results from nine published field research studies on variable rate (VR) fertilizer application are reviewed using partial budgets adjusted to include minimum costs and grid cell areas for each study. Profitability results correlated closely with the gross revenue earning potential of the crop, so VR fertilizer application was unprofitable on wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.), sometimes profitable on corn (Zea mays L.), and profitable on sugarbeet (Beta vulgaris subsp. L. vulgaris). Although the formal published literature has ignored the profitability of yield mapping, production economics and farmer interviews suggest that yield mapping is profitable when it reveals yield patterns that can be managed at acceptable cost and when the information has compensating off-field value. Manageable yield variability includes not only VR input management, but also whole-field improvements such as field drainage, land leveling, windbreaks, and fencing. Off-field value can come from cheaper on-farm experimentation and greater negotiating power with landlords. Farmers and agribusinesses committed to field crop production for the long term should develop SSF capabilities. But because SSF practices are site-specific, their profitability potential too is site-specific. This site specificity extends beyond the farm field to the crop rotation, and the capabilities and opportunities available to the farm or agribusiness manager.

The wide scale adoption of site specific management (SSM) and variable rate fertilizer application (VRA) in the next 5 to 10 years portends changes in soil testing and plant analysis. To develop site specific nutrient recommendations, more detailed information about the soil's fertility status will be required which could mean greatly increased samples numbers for soil or plant analysis. Discussions of initial research on the large numbers of samples required to produce quality maps for SSM and VRA among scientists, agricultural industry and producers, however, indicates that this may only be a short phase as the expectation of using remote sensing (RS) to replace or compliment limited soil and plant analysis is already occurring. Soil and plant analysis numbers may increase during the next 5 to 10 years as there is a slow transition to SSM and VRA. During this time, however, there will be research to related RS imagery to soil and crop management problems. After 10 years of this transition, there may be more adoption of RS for primary diagnosis and management with limited soil and plant analysis done from ‘reference’ areas to assure the accuracy of remotely sensed image interpretation.

Variable rate fertilizer application has the potential to improve fertilizer use efficiency, increase economic returns,and reduce environmental impacts. This study was designed to examine differences in yield and economic returns betweenuniform and variable rate fertilizer applications. During the 1997 and 1998 growing seasons, a variable rate applicator,capable of varying two liquid fertilizers simultaneously, was used to evaluate three fertility strategies: conventional uniformN, uniform N and P, and variable rate N and P. The three treatments were assigned in six blocks within three 14ha grainsorghum fields (two blocks in each field) in a randomized complete block design. Thirtysix soil samples were taken in astaggered systematic grid from each field, and levels of soil nutrients were determined. Application rate maps for the variablerate N and P treatment were generated based on a fixed yield goal and sitespecific soil N and P levels across the experimentalplots, while application rates for the uniform N and P treatment were calculated from the same yield goal and average soilN and P levels for all three fields. Yield monitor data indicated that the variable rate treatment resulted in significantly higheryields than the uniform N and P treatment for both years (400 kg/ha higher in 1997 and 338 kg/ha higher in 1998). Moreover,coefficients of variation of yield monitor data for the variable rate treatment were smaller than those for the two uniform ratetreatments. A simple economic analysis showed that the variable rate treatment had positive relative economic returns overthe uniform N and P treatment ($27/ha in 1997 and $23/ha in 1998). However, if additional costs for soil sampling, equipment,and data analysis associated with variable rate application were considered, these returns would be much lower or evennegative. These results showed that variable rate fertilization can increase yield, reduce yield variability, and improveeconomic returns. More experiments are needed to evaluate the longterm agronomic, economic, and environmental viabilityof variable rate technology in the Rio Grande Valley of south Texas

HighlightsThe influencing factors of the fertilizer dropping time are determined by simulation.The relationship between the influencing factors and the fertilizer dropping time is explored on the VRF applicator.A new method is established to calculate the fertilizer dropping time.Abstract. Lag time is one of the main factors that affect the accuracy of the variable rate fertilizer (VRF) applicator. The key to correcting the impact of the lag time is to determine its influencing factors. This article focuses on the fertilizer dropping time, which is a part of the lag time, and hypothesizes that the rotational speed of the fluted roller, working length of the fluted roller, number of fertilizer particles, and the length of the fertilizer tube may affect the fertilizer dropping time. First, taking advantage of the simple and convenient setting of the working parameters and conditions of the simulation software, different working parameters were set by the EDEM software for simulation, and the simulation results were analyzed to determine that the rotational speed of the fluted roller and the length of the fertilizer tube are the main influencing factors of the fertilizer dropping time. Second, to explore the relationship between the two factors and the fertilizer dropping time in the actual work, experiments were performed on the VRF applicator. The experimental results are analyzed by ANOVA, and the analysis results show that: the correlation coefficient R2 between the rotational speed of the fluted roller and fertilizer dropping time is greater than 0.95, and there is a linear relationship between the factor and fertilizer dropping time; the fertilizer dropping time increases with increasing the length of the fertilizer tube. Finally, the rotation speed-the length of the fertilizer tube-fertilizer dropping time model was established through the multiple regression analysis. With the model, the fertilizer dropping time was accurately calculated according to the rotational speed of the fluted roller and the length of the fertilizer tube. The accuracy of the model is greater than 85%, which helps to calculate the fertilizer dropping time. This study helps to correct the lag distance by sending instructions in advance and improving the accuracy of the VRF applicator. Keywords: Fertilizer dropping time, Fertilizer tube, Rotation speed, VRF.

Optical spectrometry sensors in crops offer a remarkable technological breakthrough in the field of variable-rate nitrogen fertilization. A field study was conducted during rainy (kharif) season of 2021 at the research farm of the Agricultural Engineering College and Research Institute Tamil Nadu Agricultural University Coimbatore to estimate maize crop nitrogen (N), Normalized Difference Vegetation Index (NDVI) value and chlorophyll content in hybrid maize COH (M) 8. Fertilizers were administered to the plots following the recommendations (250:75:75 kg NPK ha-1) given under Soil Test Crop Response, with a goal yield of 9t ha-1 predicted based on the initial soil available N, P, and K values. The experimental findings revealed a significant impact of nitrogen rate (P<0.001) on the percentage of nitrogen content in the leaves (% N leaf content). Additionally, there was a decrease in maize leaf chlorophyll content index over time, with ranges of 32.96 to 50.57, 28.78 to 41.78, 24.81 to 35.86, 22.12 to 28.54, and 14.34 to 20.56. On the contrary, the NDVI experienced an increase throughout the season, with ranges of 0.32 to 0.49, 0.30 to 0.55, 0.28 to 0.66, 0.46 to 0.88, and 0.56 to 0.84. The study will help foster sustainability within modern intensive farming practices by emphasizing the importance of reducing environmental pollution caused by applying Sensor-based site-specific nitrogen fertilizer for maize crop.

Measuring of fruit tree canopy parameters were required for site-specific management of fruit orchard such as estimation of fruit yield, variable rate application of fertilizer and pesticides precisely on each tree. For riding the effect cased by tractor deviation in driving path between two rows of trees and uneven ground, measuring was designed based on CAN bus, combined robot navigation technology, including AHRS and DGPS-RTK, with the measuring of fruit tree canopy characters, and used C8051F040 micro controller as node ECU. The hardware circuit was introduced in detail, the forming of CAN transmission information frame and software were also analyzed. Experiment with litchi trees in orchard using four ultrasonic sensors showed that system was stable, having highly repeatability (R2=0.9341, RMSE=1.22m3) and accuracy (R2=0.8972, RMSE=1.766m3) of canopy volume measuring.

This review paper synthesizes the current understanding of greenhouse gas (GHG) emissions from field cropping systems. It examines the key factors influencing GHG emissions, including crop type, management practices, and soil conditions. The review highlights the variability in GHG emissions across different cropping systems. Conventional tillage systems generally emit higher levels of carbon dioxide (CO2) and nitrous oxide (N2O) than no-till or reduced tillage systems. Crop rotation, cover cropping, and residue management can significantly reduce GHG emissions by improving soil carbon sequestration and reducing nitrogen fertilizer requirements. The paper also discusses the challenges and opportunities for mitigating GHG emissions in field cropping systems. Precision agriculture techniques, such as variable rate application of fertilizers and water, can optimize crop production while minimizing environmental impacts. Agroforestry systems, which integrate trees and crops, offer the potential for carbon sequestration and reducing N2O emissions. This review provides insights into the latest research on GHG emissions from field cropping systems and identifies areas for further study. It emphasizes the importance of adopting sustainable management practices to reduce GHG emissions and enhance the environmental sustainability of agricultural systems.

In the U.S. Northern Great Plains, growing seasons are short but extremely productive. Farms and ranches are large, so many of precision agriculture's early adopters reside in the region. Crop yield maps at season's end reveal sizable variations across fields. Farm management relying upon uniform chemical applications is ineffective and wasteful. We provided information about crop and range status in near- real-time, so that in-season decisions could be made to optimize final yields and minimize environmental degradation. We created learning communities, in which information is shared among scientists, farmers, ranchers, and data providers. The new information for agricultural producers was satellite and aerial imagery. Value-added information was derived from ETM+, AVHRR, IKONOS, and MIDOS sensors. The emphasis was on reducing the time between acquisition of data by a satellite and delivery of value-added products to farmers and ranchers. To distribute large spatial data sets in short times to rural users we relied upon satellite transmission (Direct PC). Results include: (1) management zone delineation, (2) variable-rate fertilizer applications, (3) weed detection, (4) irrigation efficiency determination, (5) detection of insect infestation, (6) specification of crop damage due to inadvertent chemical application, and (7) determination of livestock carrying capabilities on rangelands.

What is lacking in precision farming at present, are more comprehensive and non-destructive methods for obtaining the data needed to prescribe variable treatments. A farmer needs to be informed in order to be efficient, and that includes having the knowledge and information products to forge a viable strategy for farming operations. Current remote sensing (satellite images) sources are too coarse in multispectral spatial resolution and too infrequent in time to allow detailed tracking of phenological stages during the growing season. In this research very detailed and automated on-the-go optical monitoring of the crop is used for detecting and managing zones with different crop yield potential on a seasonal scale. In particular, reflectance properties are used to identify and evaluate optical indicators of the nutritional status of the crop. These indicators should allow site-specific in-seasonal correction of N-application to come to optimal crop yield all over the field. Based on these indicators, site-specific fertilization is done with a variable fertilizer equipped with DGPS. At the end of the season, the crop was harvested with a combine harvester, equipped with precision farming sensors to map final crop yield. In this way final results could be evaluated and analyzed.

Input management practices within precision agriculture systems have enabled grain and oilseed producers to apply agricultural inputs variably, facilitating resource, yield, and profit optimization. Despite significant progress in variable rate technologies, research comparing different methodologies and comprehensive guidelines to assist producers in their decision‐making processes is still lacking. This research article aimed to identify and summarize the suggested decision‐making factors for determining variable seed rates and variable fertilizer applications. A systematic review of the literature from the last 2 decades was conducted, summarizing various approaches within precision agriculture related to variable rate applications in canola ( Brassica napus L.), maize ( Zea mays L.), soybean [ Glycine max (L.) Merr.], and wheat ( Triticum aestivum L.). Findings revealed a wide range of decision‐making factors guiding variable rate applications, from site‐specific soil characteristics to complex data‐driven recommendations. Focus crops were maize and soybean in terms of variable seeding rates, while nitrogen was the only fertilizer source discussed. Most articles appeared to address a single specific decision‐making factor, with limited comparisons drawn between different methods. The results underscore the complexity of variable rate decisions, especially in terms of the influence of weather, highlighting the overarching impact that rainfall has on grain and oilseed production in dryland systems. To maximize the effectiveness of variable rate applications across diverse production systems and justify the initial investment in these technologies, it is essential to develop adaptable, context‐specific guidelines for seed and fertilizer management.

Every year, large amounts of agricultural land are threatened by water erosion. Fields with sloping land are particularly at risk. The impact of water erosion on soil and fine soil particles is very serious. Water erosion is a natural process and cannot be stopped. It can only be reduced or slowed down. To reduce the impact of water erosion, erosion control measures are used to protect the soil surface and fine soil particles. The most risk crops from the view of water erosion are wide-row crops. The aim of this research was to assess the effect of organic fertilizers on soil erosion parameters in maize crop. To achieve the results, a field experiment focusing on three organic fertilizers (manure, digestate, compost), was established on a sloping plot with an average slope of 5.29°. Each fertilizer was represented in two variants at different rates. Two variants were added as a control. One with maize cover without fertilizer application and the second without vegetation. Surface runoff and erosive wash were measured using the micro-parcel runoff method. Based on the results from the measurements, a positive effect of organic fertilizers on water erosion mitigation can be demonstrated, primarily reducing erosive wash and surface runoff. Both are associated with improved soil infiltration. It is therefore possible to consider the use of infiltration strips with extreme doses of organic fertiliser on erosion-prone areas of land. Furthermore, there was no confirmation of the expected reduction in soil water infiltration for the option where digestate was applied.

Cada sistema de manejo do solo é trabalhado de maneira própria, alterando de forma diferenciada suas propriedades químicas, físicas e biológicas, podendo requerer modificações nas recomendações e no manejo da adubação. Com a finalidade de avaliar o desempenho de três cultivares de milho em relação à adubação realizada em pré-semeadura, comparada à adubação na semeadura, em dois sistemas de manejo do solo, foi realizado este estudo. O experimento foi conduzido na Faculdade de Ciências Agronômicas da UNESP, campus de Botucatu-SP, no período de novembro de 2003 a maio de 2004, em Nitossolo Vermelho distroférrico. O delineamento experimental utilizado foi o de blocos ao acaso com parcelas subsubdivididas e quatro repetições. As parcelas foram constituídas pelos sistemas de manejo do solo (plantio direto e preparo reduzido com escarificação); as subparcelas, pelas épocas de adubação (adubação de pré-semeadura na superfície do solo, realizada 22 dias antes da semeadura do milho, e adubação feita junto com a semeadura do milho, sendo os fertilizantes incorporados ao solo); e as subsubparcelas, pelos cultivares de milho (DKB 333B, CO 32 e AL Bandeirante), totalizando 12 tratamentos. Os dados de produtividade, componentes de produção e teores de N, P e K no tecido foliar foram submetidos à análise de variância e às análises multivariadas de agrupamentos e de componentes principais. Os sistemas de manejo do solo não influíram no desempenho da cultura do milho, tampouco as épocas de adubação. As diferenças observadas nos componentes de produção e no desempenho da cultura do milho foram decorrentes, principalmente, da divergência genética dos cultivares de milho.

Different types of phosphate fertilizers (PFs) used in agriculture to increase soil fertility contain uranium (U) as an accompanying element. Uranium is both toxic and slightly radioactive. This study investigated the concentrations of U in phosphate rocks (PRs) and PFs used in growing tobacco (Nicotiana tabacum L.) and maize (Zea Mays L) plants from Burundi, Kenya, Rwanda, Tanzania, and Uganda. The results showed that the concentrations of U in phosphates from Burundi, Kenya, Tanzania and Uganda were statistically significant (P ≤ 0.01). The lowest U concentration was 10.7 mg kg−1 found at the Mrima Hill deposit in Kenya and the highest was 631.6 mg kg−1 found at the Matongo deposit in Burundi. Uranium concentrations for local and imported PFs was also statistically significant (P ≤ 0.01). Uranium concentration from PFs ranged from 107.88 ± 9.60 and 281.57 ± 15.82 mg kg−1 . The study also assessed the influence of U from PFs on the radioactivity of agricultural soils and uptake by tobacco plants. The results showed that applications of PFs in agricultural soils increased radioactivity in agricultural soil and tobacco crops. Tobacco smoking and snuffing behaviors resulted in an annual effective dose that was 2.41-6.53 and 1.14-2.45 times greater than annual recommended effective doses for snuffers and smokers. This work also investigated the influence of fertilizer derived U on maize plant uptake and bacterial diversity in soil after application of fertilizers with varying U concentrations. The pilot field experiments showed that application of PFs with different U concentrations influenced bacteria abundance and diversity in maize crops. Applications of Nafaka plus (NP) (3.93 mg kg-1 ) and Minjingu Powder (MP) (3.06 mg kg-1 ) PFs in soil increased bacteria abundance and diversity. Some bacteria were abundant on NP treated soil (high U content) because of their ability to tolerate higher U concentrations. Uptake from soil to crop for maize after applications of PFs of varying U concentrations was investigated by amending soil with Eucalyptus globulus ssp maideii bark and kaolin clay. The soil amendments in reduced U uptake from soil to plant in pot experiments. It is believed that the reduced U uptake is associated with eucalyptus globulus ssp maideni carboxyl groups that can reduce mobile hexa-uranyl ions to immobile tetra uranyl ions that can be absorbed by the kaolin clay. The study recommends further work in understanding the mechanisms of Eucalyptus ssp maidenii bark powder and kaolin U uptake reduction in soil complex matrix.

Inappropriate soil fertility management has caused fertility to decline considerably over the years leading to low maize yields despite the growing human population with high food demand in Kenya. Despite high nutrient mining, fertilizer use and adoption of soil fertility improvement practices have remained low among maize farmers in the country. At the current yield levels, maize crops extract over 40, 8, 40.6, and 5.4 kg of N, P, K, and S per growing season, respectively. These extracted nutrients must be replaced to avoid nutrient depletion. Maize crop response to secondary macronutrients (S, Ca, and Mg) and micronutrients (Zn and B) is evidenced, signifying that these nutrients have also reached critical levels in Kenya soils. The rate of replenishing these lost nutrients is still low, farmers apply an average of 43.25 kg of fertilizer per hectare per season. The situation is worsened further by increasing soil acidity- currently below pH 5.5 in most maize-growing regions. Poor agronomic practices applied by farmers directly reduce yields and facilitate other factors leading to nutrient losses. For example, farmers across the country recycle seeds, apply low fertility rates, and rarely keep their fields weed-free. These practices lower the capacity of the crops to tolerate the impact of other production constraints including infertility. To realize yield improvement and return on investments, farmers must adapt and adopt crucial practices under integrated soil fertility management. Managing soil acidity should be the first approach to unlocking fixed nutrients. Fertilizer application should follow the right rate, right source, right time, and right placement approach. Also, improved cropping systems such as maize-legume rotation and intercropping should be considered for sustainable soil fertility management and crop production.

The parasitic weed Striga asiatica is a serious problem in maize crops in southern Malawi and much of the rest of southern Africa. The authors spent two years studying farmer knowledge of the weed in an area of south-eastern Malawi, and the links between population pressure, soil fertility and Striga incidence. Following a discussion of the history of the study village, the results of a series of field trials are presented which test the effect of altered fertilizer applications on yields of maize plants in Striga infested areas. These show that simply changing the timing of fertilizer application, using the rates farmers currently use, could have a dramatic effect on the maize plant's ability to cope with the weed and on the economics of maize production.