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This study aims to evaluate the effects of different parameter settings on the ditching performance using a ditching-fertilizer. We aimed to improve the performance of ditching-fertilizer machine performance in sustainable agriculture. With Box-Behnken experimental design method, taking forward speed, the rotation speed of the ditching cutter, and the deflection angle of ditching cutter as experimental factors, taking ditching depth stability and soil coverage rate as test indexes, the operation parameters of orchard ditching-fertilizer machine are studied. The regression model between test indexes and experimental factors is established, and the influence of each factor on the experimental indexes is analyzed. The test factors are comprehensively optimized. The results show that when the forward speed is 0.8km/h, the rotation speed of the ditching cutter is 348r/min, and the deflection angle of the ditching cutter is 32°, the ditching effect is the best. At this time, the stability coefficient of the ditching depth is 98.33%, and the soil coverage rate is 81.53%. As for the field test, which measured the stability coefficient of ditching depth, and the average soil cover rate is 96.24%, and 79.14%, respectively, and the relative errors from the optimized value are 2.17%, and 3.02%, respectively.

Fertilizer sphericity is an important assessment index of appearance quality that affects the fertilization effect. A fertilizer sphericity measuring device based on machine vision was designed aimed at low precision and heavy workload of manual fertilizer measurement, and high cost and complicated operation of high precision measuring instruments. A fertilizer sphericity measuring method based on equatorial and meridian circles was proposed. The device works in an intermittent static acquisition mode to simultaneously obtain both top and side images of a single fertilizer. First, the method performs gamma correction on the top and side images of the single fertilizer, and uses the Canny operator to detect the edge of the image to obtain the equatorial and meridian circular contour images of the fertilizer. Second, based on the fertilizer equatorial and meridian circular contour, the Least Squares Circle method was used to evaluate the roundness of the single fertilizer. Finally, the average roundness value of the equatorial and meridian circles was used as the final sphericity value of the fertilizer. The sphericity measurement test was carried out on the same batch of compound, organic and biological fertilizers by using the sphericity measuring device. The fertilizer sphericity data were obtained by different measurement and evaluation methods. The variation coefficient was used to evaluate the difference in fertilizer sphericity measured by different sphericity measurement and evaluation methods. The results show that among the different measurement and evaluation methods, the coefficient of variation of fertilizer sphericity measured by the equatorial and meridian circle method was the smallest, and the coefficient of variation of sphericity measured by the Least Squares Circle method was the smallest and accurate. This study shows that the sphericity measuring device and method can accurately measure the fertilizer sphericity, and has a significant potential to facilitate fertilizer production and quality inspection.

The accurate prediction of fertilizer crushing force could reduce the crushing rate in the process of transportation and utilization and ensure the efficient utilization of the fertilizer so as to realize the sustainable and clean production of crops. To achieve this goal, a fertilizer crushing force prediction model based on the shape characteristics was proposed in this paper using the Pearson correlation coefficient, differential evolution algorithm, and the support vector machine (P-DE-SVM). First, the shape characteristics and crushing force of fertilizers were measured by an independently developed agricultural material shape analyzer and digital pressure gauge, and the shape characteristics related to the fertilizer crushing force were proposed based on the Pearson correlation coefficient. Second, a fertilizer crushing force prediction model based on a support vector machine was constructed, in which the optimal kernel function was the radial basis function. Finally, a differential evolution algorithm was proposed to optimize the internal parameters of the fertilizer-crushing force prediction model, and at the same time, a fertilizer granularity inspection range was calculated. The experimental results showed that the maximum error rate of the fertilizer crushing force prediction model was between -10.4 and 10.9%, and the fertilizer granularity inspection range was reasonable. The proposed prediction model in this paper could lay a solid foundation for fertilizer production and quality inspection, which would help reduce fertilizer crushing and improve fertilizer utilization to realize the sustainable and clean production of crops.

In order to detect the soluble solids content of apples quickly and accurately, a portable apple soluble solids content detector based on USB2000 + micro spectrometer was developed. The instrument can communicate with computer terminal and mobile app through network port, Bluetooth and other ways, which can realize the rapid acquisition of apple spectral information. Firstly, the visible / near-infrared spectrum data and soluble solids content information of 160 apple samples were collected; secondly, the spectral data preprocessing methods were compared, and the results showed that the prediction model of sugar content based on partial least square (PLS) method after average smoothing preprocessing was accurate. The correlation coefficient (RP) and root mean square error (RMSEP) of the prediction model were 0.902 and 0.589 ° Brix, respectively. Finally, on the basis of average smoothing preprocessing, competitive adaptive reweighted sampling (CARS) and successive projections algorithm (SPA) were used to optimize the wavelength of spectral data, and PLS model was constructed based on the selected 17 characteristic wavelengths, which can increase the accuracy of soluble solids content prediction model, increase the RP to 0.912, and reduce RMSEP to 0.511 ° Brix. The portable visible / near infrared spectrum soluble solids prediction model based on the instrument and method has high accuracy, and the detector can quickly and accurately measure the soluble solids content of apple.

Discrete Element Method was used to study the fertilizer guiding mechanism of double-row orchard ditching fertilizer to solve certain problems, such as the low uniformity of fertilization in orchard. Firstly, on the basis of studying the existing B fertilizer guiding mechanism, A and C fertilizer guiding mechanisms were proposed, and three virtual simulation models of the fertilizer guiding mechanism were established. Secondly, the physical parameters of the fertilizer particles were analysed, combined with the dynamic analysis of the falling process of the fertilizer particles, the dynamic model of the fertilizer particles in the three fertilizer guiding mechanisms was established. Finally, three kinds of fertilizer guiding mechanisms A, B and C were analyzed by the discrete element simulation experiment, and the C fertilizer guiding mechanism was the best. Then, the C fertilizer guiding mechanisms under different curvature radius were simulated, the discrete coefficients of the edge region and the middle region were used to evaluate the fertilizer uniformity, and the optimal curvature radius of the C fertilizer guiding mechanism was obtained. The results of simulation and prototype orchard experiments show that the dispersion coefficients of the edge region and the middle region of the C fertilizer guiding mechanism are the smallest, the uniformity of fertilization is the highest, the A fertilizer guiding mechanism is the second, the B fertilizer guiding mechanism is the lowest; in the C fertilizer guiding mechanism under different radius of curvature, when the radius of curvature is 600mm, the dispersion coefficients of the edge region and the middle region of the C fertilizer guiding mechanism are the smallest, and the fertilization uniformity is the highest; after the optimization, the discrete coefficient is reduced from 0.51 to 0.26, and the fertilization uniformity is increased by 49.02%. This study has significant potential to design and processing of orchard ditching fertilizer applicator.