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Item Grape yield analysis with 3D cameras and ultrasonic phased arrays : a thesis by publications presented in fulfillment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Albany, New Zealand(Massey University, 2024-01-18) Parr, BadenAccurate and timely estimation of vineyard yield is crucial for the profitability of vineyards. It enables better management of vineyard logistics, precise application of inputs, and optimization of grape quality at harvest for higher returns. However, the traditional manual process of yield estimation is prone to errors and subjectivity. Additionally, the financial burden of this manual process often leads to inadequate sampling, potentially resulting in sub-optimal insights for vineyard management. As such, there is a growing interest in automating yield estimation using computer vision techniques and novel applications of technologies such as ultrasound. Computer vision has seen significant use in viticulture. Current state-of-the-art 2D approaches, powered by advanced object detection models, can accurately identify grape bunches and individual grapes. However, these methods are limited by the physical constraints of the vineyard environment. Challenges such as occlusions caused by foliage, estimating the hidden parts of grape bunches, and determining berry sizes and distributions still lack clear solutions. Capturing 3D information about the spatial size and position of grape berries has been presented as the next step towards addressing these issues. By using 3D information, the size of individual grapes can be estimated, the surface curvature of berries can be used as identifying features, and the position of grape bunches with respect to occlusions can be used to compute alternative perspectives or estimate occlusion ratios. Researchers have demonstrated some of this value with 3D information captured through traditional means, such as photogrammetry and lab-based laser scanners. However, these face challenges in real-world environments due to processing time and cost. Efficiently capturing 3D information is a rapidly evolving field, with recent advancements in real-time 3D camera technologies being a significant driver. This thesis presents a comprehensive analysis of the performance of available 3D camera technologies for grape yield estimation. Of the technologies tested, we determined that individual berries and concave details between neighbouring grapes were better represented by time-of-flight based technologies. Furthermore, they worked well regardless of ambient lighting conditions, including direct sunlight. However, distortions of individual grapes were observed in both ToF and LiDAR 3D scans. This is due to subsurface scattering of the emitted light entering the grapes before returning, changing the propagation time and by extension the measured distance. We exploit these distortions as unique features and present a novel solution, working in synergy with state-of-the-art 2D object detection, to find and reconstruct in 3D, grape bunches scanned in the field by a modern smartphone. An R2 value of 0.946 and an average precision of 0.970 was achieved when comparing our result to manual counts. Furthermore, our novel size estimation algorithm was able accurately to estimate berry sizes when manually compared to matching colour images. This work represents a novel and objective yield estimation tool that can be used on modern smartphones equipped with 3D cameras. Occlusion of grape bunches due to foliage remains a challenge for automating grape yield estimation using computer vision. It is not always practical or possible to move or trim foliage prior to image capture. To this end, research has started investigating alternative techniques to see through foliage-based occlusions. This thesis introduces a novel ultrasonic-based approach that is able to volumetrically visualise grape bunches directly occluded by foliage. It is achieved through the use of a highly directional ultrasonic phased array and novel signal processing techniques to produce 3D convex hulls of foliage and grape bunches. We utilise a novel approach of agitating the foliage to enable spatial variance filtering to remove leaves and highlight specific volumes that may belong to grape bunches. This technique has wide-reaching potential, in viticulture and beyond.Item A study of the influence of spacing within rows and seed tuber size upon the yield of the potato crop : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agriculture Science at Massey University(Massey University, 1966) Anang, HusinThe potato is one of the main food crops grown in New Zealand, and has been established since the time of European settlement In the early years production was concerned mainly with meeting the demands of the growing population. This resulted in a rapid and steady inorease in the total acreage grown. However, in the last decade, increase has been gained largely through intensification of orop areas rather than their extensification. Consequently, a diminishing increase in acreage grown has resulted. The above pattern is clearly illustrated in the following figures (extracted from Farm Production Statistics of New Zealand 1963 - 1964) [From Introduction]Item A study of the influence of spacing within rows and seed tuber size upon the yield of the potato crop : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agriculture Science at Massey University, New Zealand(Massey University, 1966) Anang, HusinUndoubtedly there is a need for more intensive research on improving methods of growing potatoes. One aspect which has a major influence on plant population is seed spacing and seed size. The project reported herein was designed to study the effect of different levels of spacing and seed size, together with their interactions, on terminal yield of potato crops. In view of the need to study other important factors influencing yield, the investigation was extended to include the effects of seed spacing and size on growth and development of the crops.Item Improving shallot (Allium cepa Aggregatum group) production in acidic soils in West Java, Indonesia : a dissertation presented in partial fulfilment of the requirements for the degree Doctor of Philosophy of Gina Aliya Sopha in Horticulture at Massey University, Manawatu, New Zealand(Massey University, 2022) Sopha, Gina AliyaIn the West Java region, Indonesia, the wide range of shallot (Allium cepa) bulb yields suggests that there is potential for productivity improvements, especially for smallholder farmers. This study, which involved a farmer and soil fertility survey, two field trials and a laboratory incubation study, aimed to improve the shallot productivity of smallholder farmers. The survey, conducted in four districts of West Java, identified that the Pacet District had the lowest average bulb yield of 5.4 t ha⁻¹ and also had a wide range of yields (2.3 to 11.8 t ha⁻¹). The two common soil fertility constraints were very low soil pH and low available soil phosphorus (P). The first field trial aimed to determine the optimal P fertiliser rates, when rates of up to 1 tonne of lime ha⁻¹ were applied, for three different farm sites in the Pacet District. These sites had strongly acidic soils with constraining exchangeable Al³⁺ and available soil P levels. The second field trial aimed to determine the response of shallot bulb yield to P fertiliser once exchangeable Al³⁺ had been decreased to a low level using high rates of lime. This field trial used a single farm site with a very low soil pHH₂O of 4.1, a high exchangeable Al³⁺ of 1.9 cmol (+) kg⁻¹ and a low Bray1-P of 10 mg P kg⁻¹. The incubation experiment assessed the effect of a range of liming materials, as well as rice husk biochar and zeolite, on soil pH, exchangeable Al³⁺ and cation exchange capacity (CEC). This study quantified the benefits of improved lime and P fertiliser practices and identified constraints to their implementation. Farmers should aim to ensure that soil exchangeable Al³⁺ levels are maintained < 0.5 cmol (+) kg⁻¹, which will be at soil pH levels of approximately > 4.7. Monitoring soil P status through soil testing and achieving Bray1-P levels above 28 kg ha⁻¹ also improves the likelihood of achieving high yields. Very good financial returns can be achieved from high yielding shallot crops; however, farmers need better access to the services of agricultural field officers to conduct and interpret soil tests.Item Development of sustainable nutrient management strategies for taro growers on Taveuni Island, Fiji : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science, Massey University, Palmerston North, New Zealand(Massey University, 2021) Lal, RohitTaro (Colocasia esculenta) is a major component of the socio-cultural, dietary and economic livelihood of Pacific Island countries, including Fiji. However, Fiji’s total taro exports have substantially declined over the last decade, mainly due to a reduction in production from Taveuni Island. A trend of decreasing taro yields has been further exasperated by recent extreme climate events, which have reduced the availability and affordability of planting material. The combination of lower yields and increased costs, have reduced farmers’ returns on existing farm land, which has contributed to further deforestation of forest reserves. The overall aim of this study was to develop improved nutrient management practices on existing farm land, to help growers to achieve sustainable taro yields and financial returns. This study included a survey of 73 taro farmers, which involved a quantitative analysis of taro yields and soil fertility. Fresh taro corm yields were very low, being an average of 6.9 t/ha. About 75% of the farms surveyed had low soil Olsen phosphorus (P) levels of < 10 mg/kg and 65% had low soil exchangeable potassium (K) levels of < 0.4 me/100g. Fertiliser nutrient inputs were also low, with semi-commercial farmers using an average of 31 kg nitrogen (N), 17 kg P and 27 kg K/ha, and commercial growers using an average of 41 kg N, 26 kg P and 40 kg K/ha per crop. The survey also identified that fertiliser placement and application timing practices may also reduce nutrient use efficiency by the crop. Two successive field experiments were repeated over three sites, on Taveuni Island, to evaluate a range of nutrient management strategies to improve soil fertility and taro productivity. When no N and P fertiliser was applied, average fresh taro corm yields were very low (6.2 t/ha), irrespective of K and sulphur (S) fertiliser inputs. The addition of up to 200 kg N/ha and 120 kg P/ha, resulted in a substantial average yield increase to 14.9 t/ha. Taro yields were also responsive to K fertiliser use, with significant increases in yield up to 200 kg K/ha, the highest rate of K assessed. There was a strong linear relationship between N fertiliser use and taro sucker population up to 300 kg N/ha. In the second experiment, sucker numbers increased with increasing N fertiliser rate up to 280 kg N/ha. Further increasing N rates up to 360 kg N/ha did no further increase sucker production. When no fertiliser was applied, average taro sucker population across the three sites was about 20,500 suckers/ha, which increased to about 122,500/ha at 280 kg N/ha. The response of sucker numbers to N was not influenced by P fertiliser use, but there was a small effect with increasing K fertiliser rate, from 100 to 200 kg K/ha. Following natural disasters, when sucker numbers are limited, the use of N fertiliser may be an effective short-term strategy to help re-establish the taro industry and minimise inflated sucker prices. The use of the legume mucuna, as a green manure crop intercropped with taro, reduced N fertiliser requirements. Mucuna provided a benefit, for both corm yield and sucker numbers, equivalent to N fertiliser applied at a rate of approximately 80-100 kg N/ha. Some of the benefit may also be due to improved weed suppression and a mulching effect from mucuna. Mixing P fertiliser in the planting hole increased corm yields by 38%, compared to the when P fertiliser was placed at the bottom of the hole. Despite the high rates of P fertiliser used in the first experiment there were no significant P carry-over effects on taro yields in the second experiment. This was due to the higher soil P status from P fertiliser application being confined in close proximity to the planting holes. The Soil Plant Analysis Development (SPAD) chlorophyll meter was evaluated as being effective at predicting N status of taro crops and yield potential, when other major nutrients were non-limiting. When SPAD readings were greater than 65, at 8 and 12 weeks after planting (WAP), then the taro yields were mostly high (i.e. > 12 t/ha). SPAD readings less than 40, at 8 and 12 WAP, would indicate that plant N status is likely to limit taro yield and that a review of N fertiliser use is required. The recommended nutrient management strategy for taro farmers with farms with degraded soil fertility, involves the use of inter-cropping taro with a mucuna green manure crop in combination with fertiliser at the following nutrient rates; 120 kg N, 120 kg, 200 kg K/ha and 80 kg S/ha. At current taro corm and sucker prices, this recommended strategy is expected to provide a net income of NZ$35,835, which is 247% higher than for the average grower practice. The recommended practice also produces 74% more taro suckers than the current grower practice. Increasing sucker production is an important strategy to enable taro growers to increase production quickly following a natural disaster, helping farmers be more resilient to the effects of Climate Change.Item Predicting spatiotemporal yield variability to aid arable precision agriculture in New Zealand : a case study of maize-grain crop production in the Waikato region : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Agriculture and Horticulture at Massey University, Palmerston North, New Zealand(Massey University, 2020) Jiang, GuopengPrecision agriculture attempts to manage within-field spatial variability by applying suitable inputs at the appropriate time, place, and amount. To achieve this, delineation of field-specific management zones (MZs), representing significantly different yield potentials are required. To date, the effectiveness of utilising MZs in New Zealand has potentially been limited due to a lack of emphasis on the interactions between spatiotemporal factors such as soil texture, crop yield, and rainfall. To fill this research gap, this thesis aims to improve the process of delineating MZs by modelling spatiotemporal interactions between spatial crop yield and other complementary factors. Data was collected from five non-irrigated field sites in the Waikato region, based on the availability of several years of maize harvest data. To remove potential yield measurement errors and improve the accuracy of spatial interpolation for yield mapping, a customised filtering algorithm was developed. A supervised machine-learning approach for predicting spatial yield was then developed using several prediction models (stepwise multiple linear regression, feedforward neural network, CART decision tree, random forest, Cubist regression, and XGBoost). To provide insights into managing spatiotemporal yield variability, predictor importance analysis was conducted to identify important yield predictors. The spatial filtering method reduced the root mean squared errors of kriging interpolation for all available years (2014, 2015, 2017 and 2018) in a tested site, suggesting that the method developed in R programme was effective for improving the accuracy of the yield maps. For predicting spatial yield, random forest produced the highest prediction accuracies (R² = 0.08 - 0.50), followed by XGBoost (R² = 0.06 - 0.39). Temporal variables (solar radiation, growing degree days (GDD) and rainfall) were proven to be salient yield predictors. This research demonstrates the viability of these models to predict subfield spatial yield, using input data that is inexpensive and readily available to arable farms in New Zealand. The novel approach employed by this thesis may provide opportunities to improve arable farming input-use efficiency and reduce its environmental impact.Item Exploring the opportunities in the sweetpotato value chain in diversifying the Nigerian economy : a thesis presented in partial fulfilment of the requirements for the degree of Master of AgriCommerce at Massey University, Palmerston North, New Zealand(Massey University, 2018) Adesina, AdebowaleNigeria is the second largest producer of sweetpotato in the world and the largest producer in Africa. However, the total average yields of sweetpotato in Nigeria is comparatively low (2.6 tons per hectare) when compared to the rest of Africa (9.6 tons per hectare) and the world (16 tons per hectare). Furthermore, Nigeria is not ranked among the top 150 global exporters of sweetpotato, and the unavailability of markets has been reported to as one of the primary constraints to sweetpotato production in Nigeria. The aim of this study is therefore to explore the opportunities in the sweetpotato value chain that can contribute to the development of the Nigerian economy. A structured questionnaire survey was used to obtain information from 115 farmers who were selected through non-probability convenience sampling. The findings from the structured questionnaire were complemented by an open-ended face-to-face interview. The analysis of the findings involved descriptive and inferential statistics. With the aid of the descriptive statistics, the contributing factors to the low yield of sweetpotato were identified along with the constraints to market access and market opportunities for sweetpotato nationally and internationally. The inferential analysis using the binary logistic model was used to determine the factors that had a significant influence on the yield of sweetpotato. The constraints identified that limit the production and yield of sweetpotato farmers included: inadequate market outlets to sell increased quantity of sweetpotato; high incidence of pest and diseases; scarcity of vines for planting; lack of knowledge on pest and disease management; lack of access to financial capital to buy farm inputs and carry out necessary farm activities; early spoilage of sweetpotato roots after harvest; lack of storage facilities to increase the shelf life of harvested sweetpotato; inadequate rainfall; grazing of cattle by herdsmen on sweetpotato farms; difficulty in getting farm labourers and inadequate access to farm machinery. The empirical results of the binary logistic regression indicated that farmers age, level of formal education, gender, cultivated land area, access to extension services access to market information and membership of a farmers group all had significant positive effect on the yield of sweetpotato farmers except farmers age which had a significant negative impact on the yield of farmers. Addressing the constraint to sweetpotato production and market access had the potential to increase farmers’ productivity, annual income and access to the high-value market, alleviate poverty and contribute to the economic development of Nigeria.Item A study of the effect of the frequency of spring cutting on the regrowth and resulting yield of lucerne (Medicago sativa L.) : a thesis presented in partial fulfillment of the requirements for the degree of Master of Agricultural Science at Massey University(Massey University, 1968) Tsuma, FrancisThere is abundant evidence to show that the yield, stand, chemical composition and the feeding value of lucerne may be materially affected by varying the cutting interval. Therefore, the purpose of the field experiment reported here was to determine the effect of the frequency of spring cutting on the regrowth and resulting yied of a pure stand of New Zealand certified lucerne (Chanticleer) and on weed invasion of the stand and, if possible, the reasons for this effect. It is hoped that this information will add to the existing evidence. Lucerne is cultivated for stock feed in many parts of the world, including New Zealand. In recent years, it has become increasingly important as a forage crop because of its potential for high yields of good quality feed under a wide range of climatic and soil conditions. The long tap root of the plant affords it considerable resistance to drought. Moreover, the plant is rich in phosphates, lime and protein, all of which are essential in animal production. In common with other legumes, it possesses the power to increase the nitrogen content of the soil. [FROM INTRODUCTION]Item Root growth and crop yield of two varieties of wheat grown under differing irrigation regimes : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Plant Science at Massey University(Massey University, 1974) Piggot, Graeme JamesRoot growth and crop yield of Gamenya, a standard height variety, and Karamu, a semi-dwarf, spring wheat were compared under 3 irrigation regimes: daily watering; infrequent (fortnightly) watering; and sub-irrigation, where water was introduced into the soil profile at 40cm, the plots being protected from rainfall. Root growth and development were similar between varieties apart from an indication that the Karamu root system was more extensive at depth. The three irrigation treatments grew distinctly different root systems which was probably due partly to soil compaction differences between the treatments rather than the spatial distribution of the soil water supply. Karamu outyielded Gamenya because of a higher grain weight per ear due to higher floret viability and greater grain weight. Yield differences between irrigation treatments, where the infrequently irrigated treatment was superior, was due to ear population differences related to the differing root systems. With daily irrigation Gamenya used more water, due possibly to the lower leaf water potentials developed in the crop. An inverted water potential difference between the ear and the flag leaf was observed during the middle of the day.Item Growth studies with hemp (Cannabis sativa L.) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Horticultural Science at Massey University(Massey University, 2007) Gibson, Arthur RandallThe effect of latitude, sowing date and density on yield, height and growing time were studied by sowing two varieties of hemp for seed at three sites in New Zealand. Predation and poor germination hampered results. Latitude effects on height could not be confirmed but Anka, unlike Finola, suffered a reduction in height with later sowing. Anka was the larger plant with higher seed yield, but the dwarfed Finola gave a higher harvest index. Thus seed yield for later sowing is reduced for cv Anka, unchanged for cv Finola. Plant density data allowed estimated yields at 30, 60 and 90 plants.m-2 to be determined. At 30 plants.m-2, seed yield in both varieties was reduced with later sowing, and confirmed Anka with the greater gross yield against Finola having the higher harvest index. At 60 and 90 plt.m-2, the results confirmed only that Anka is the bigger plant. Earlier sowing than the 1st sowing in our trial (October) could be an advantage. Higher sowing rates than 40-50 plt.m-2 would be of little advantage for Anka, but rates higher than 90 plt.m-2 should be explored for Finola. The asymptotic yield maximum for Anka falls dramatically with later sowing, whereas Finola does not. This suggests double cropping might be explored, with an early sowing of Anka followed by Finola. Growing time data indicated the lower latitude site had longer growing times overall. Day length sensitivity (shorter growing time with later sowing) was confirmed for Anka, but Finola was unaffected. This suggests Finola is a day-length neutral plant. Leaf production in both varieties was higher at higher latitudes, and was reduced by later sowing date. A second experiment examined the nitrogen and phosphorus uptake of a fibre hemp cultivar (EIL1) with respect to three sowing dates and two latitudes. Harvests were taken monthly to establish growth trends. From biomass figures, equations were established for leaf/stem relationships. Uptake values (on a dry matter basis) tended to stabilize as the plant matured at: N(stem) 3.04%, N(leaf) 4.5%, p(stem) 0.26% and P(leaf) 0.45%. High initial concentration of both N and P fell rapidly. For maximum uptake seed should be sown early (October or earlier) and plants grown as long as possible (5 months or more).