Evaluation of Variable Rate Technology for Fertilizer Application in Permanent Pastures

This paper describes the field tests carried out to evaluate the new Vicon RS-EDW centrifugal fertilizer spreader, to be used in Precision Agriculture. The results of initial dynamic calibration tests showed a significant and systematic difference between the application rates of the two discs （about 20%）. This difference had to be corrected by the manufacturer that carried out the necessary changes to the electric actuators. The fertilizer spreader had good distribution homogeneity, considering different working velocities and different positions in the parcel. The pattern distribution curve for 18% super phosphate fertilizer led to an effective working width of 28 meters, with a coefficient of variation of 15%. The longitudinal test, under experimental working conditions led to a machine delay time of 6-7 seconds. The results show an actual fertilization application density between 74%-90% of that determined for each location. These results confirm that the spreader can be used to spread fertilizer differentially in the field.

Variable rate fertilization system with adjustable active feed-roll length

This paper presented a novel variable rate fertilization system based on the method of adjusting the active feed-roll length of a fluted roller.The feasibility of this method was discussed using analysis of the fluted roller model.One seed drill produced by Kuhn Company(France),which could sow and fertilize simultaneously,was used as a test platform to implement the mechanical structure of variable rate fertilization.The design methods for the variable rate fertilization mechanical structure and actuator were introduced in detail.A low-cost and stable embedded support decision subsystem and corresponding software were developed.The support decision subsystem is based on grid management.Each grid field cell contains information about corresponding spatial position and fertilizer application rate.A SpatiaLite database was employed to solve the spatial location search and spatial data query.Experiments were conducted to evaluate the fertilization uniformity and dynamic response time.The average value of coefficient of variation is 8.4%in five different active feed-roll lengths which reflects good uniformity.The dynamic response times for the adjustment of variable rate fertilization system from 204 kg/hm^(2) to 319 kg/hm^(2) and 319 kg/hm^(2) to 204 kg/hm^(2) are about 4.2 s.The results suggest that the variable rate fertilization system performs well in dynamic adjustment and stability.

Response characteristics and efficiency of variable rate fertilization based on spectral reflectance

The key technical problem of variable rate fertilization system based on spectrum information was precise variable fertilization in certain area according to the acquired spectrum information.Hysteretic fertilizing is a critical problem in most of current fertilizer equipment.Hysteresis model was built and analyzed in this study to improve the system.Fertilizing tests were conducted on different wheat breeds and the results were analyzed.The tests showed that variable rate fertilization had obvious hysteresis phenomenon with the maximum lag distance of 3.82 m,the minimum lag distance of 1.73 m and average of 3.06 m.Hysteresis phenomenon of the variable rate fertilization system was obviously decreased when implanting a correction time of 2.04 s with the maximum lag distance of 0.61 m.Variable effects varied by different wheat breeds.Variable rate fertilization had an advantage of improving spatial differences of Yangmai-23,and the spatial variability of which decreased by 14.23%.In the small test area,the amount of fertilizer in Zhenmai-168 decreased by 2.84 kg,while the amount of which in Yangmai-23 increased by 3.83 kg.Yield of Zhenmai-168 in small area was lower than that in traditional pattern,but the condition of Yangmai-23 was on the contrary.Valuable information for increasing performance of fertilization in variable rate fertilization system was provided in this paper.

Design and experiment of a subsoiling variable rate fertilization machine

In order to improve soil fertility and fertilizer utilization,a subsoiling variable rate fertilization machine based on conservation tillage and precision agriculture was designed and tested.The relationship between suspension parameters and penetrating distance was analyzed,and a matching model between fertilizing quantity and penetrating distance was established.The variable rate fertilization control machine was developed based on an Advantech PCM-9363 industrial control mainboard.The machine operates under two patterns:DGPS-based positioning and straight-line path positioning based on a planar coordinate system.This machine can perform on-demand fertilization according to the spatial differences in soil nutrients and the prescription maps pre-set before the operation.Field experiments showed the machine has a subsoiling stability of 92.5%,a soil breaking rate of 61.1%,a maximum positioning relative error of 2.68%and a maximum variable rate fertilization error of 3.89%.The subsoiling performance and variable rate fertilization indices of this machine satisfy the requirements of GB/T24675.2-2009.The tested indices meet the national and industrial standards and satisfy the design requirements.The findings of the research can be used as the structural design of the subsoiling variable rate fertilization machine.

Modification of colorimetric method based digital soil test kit for determination of macronutrients in oil palm plantation

It is the need of time that oil palm farmers must perform the spatially planned soil analysis to know about the fertilizer sufficient and deficient zones of land.Colorimetric method is a suitable and fast solution of soil analysis for NPK determination using the digital soil test kit.NPK determination procedure with a digital soil test kit was undefined for oil palm.Furthermore,the digital soil test kit determines the passage of light through an opaque medium of soil solution with a specified reagent.Therefore,environmental light may interfere leading to wrong results of NPK measurement.Likewise,this equipment was non-incorporable with the controller of any VRT fertilizer applicator.In this research,these issues were addressed and the NPK measurement procedure was defined for oil palm plantation by modifying the‘soil to water’ratio in sample soil solution with an optimum environmental light range of 18-23 W/m^(2).‘Soil to water’ratios were found for nitrogen,phosphorus and potassium as 0.31 to 5.00,1.00 to 5.00 and 4.50 to 5.00,respectively to fit the requirement of NPK for oil palm in the prescribed range of the equipment.Validation study of modified digital soil test kit showed that 91.7%N,89.6%P and 93.8%K results of modified digital soil test kit were matched with analytical laboratory method.Thus,the reliability of NPK results using digital soil test kit was enhanced,making the kit incorporable with the controller of variable rate fertilizer applicator through remote monitoring based data acquisition system.The outcome of this research can be used in the development of an IoT network data fusion for dynamic assessment of the NPK variation in the soil and nutrient management in oil palm plantations.

Wolfberry tree dual-model detection method and orchard target-oriented fertilization system based on photoelectric sensors

Orchard target-oriented fertilizing with on-board sensor technology can improve fertilizer efficiency and reduce environmental pollution.Photoelectric sensors are widely used for object detection because of their low cost and fast response time.This paper presents a Wolfberry tree dual-model detection method and the design of an orchard target-oriented variable-rate fertilization system based on photoelectric sensors.The dual-model detection method includes the Trunk Detection Model(TDM)and Canopy Detection Model(CDM),which can be applied for Wolfberry orchards at the green cluster and mature stages,respectively.A target-oriented fertilization system was designed using the dual-model method,and tested in the lab and Chinese Wolfberry orchard.The laboratory test results showed that the average center offset distances on the condition of detecting trunks,continuous canopies,and discontinuous canopies were 4.1 cm,9.1 cm and 13.1 cm,respectively.The system could ignore the signals from canes when their diameters were less than 16 mm,and also could determine the gaps within a tree when they were less than 21 cm.The orchard test results showed that the system accomplished target-oriented fertilization 95 times for 92 trees at the mature stage.The results indicated that the dual-model detection method could be used for Wolfberry trees or other trees with similar canopy changes at different growth stages.