Crop Demand Research Articles

Evaluating water quality benefits of manureshed management in the Susquehanna River Basin.

Manureshed management guides the sustainable use of manure resources by matching areas of crop demand (nutrient sinks) with areas generating livestock manure (nutrient sources). A better understanding of the impacts of manureshed management on water quality within sensitive watersheds is needed. We quantified the potential water quality benefits of manureshed-oriented management through scenario-based analyses in the Susquehanna River Basin (SRB) using the Soil and Water Assessment Tool. Five manureshed management scenarios were developed and compared with a baseline "business-as-usual" scenario. The baseline assumes manure is less transportable, which means some locations have manure application in excess of crop demand. The "watershed nutrient balance" scenarios assume excess manure from surplus locations is transportable and that manure is applied around the SRB based on crop nutrient demand. The "watershed nutrient balance avoiding runoff prone areas" scenarios assume manure is transportable but not applied in vulnerable landscapes of the SRB. Each scenario was evaluated under two application rates considering crop nitrogen demand (N-based) and phosphorus demand (P-based). Phosphorus-based manureshed management was more effective in water quality improvements than N-based management. Phosphorus-based nutrient balance scenarios simulated 3 and 25% reduction in total N (TN) and total P (TP), respectively, from the baseline scenario at the watershed outlet. The N- and P-based scenarios avoiding runoff prone areas simulated 3 and 6% reduction in TN loss and 4 and 25.2% reduction in TP loss, respectively, from the baseline. Overall, the manureshed management scenarios were more effective in improving the quality of local streams in livestock-intensive regions than at the watershed outlet.

OPTRAM-ET: A novel approach to remote sensing of actual evapotranspiration applied to Sentinel-2 and Landsat-8 observations

Satellite remote sensing technology provides a promising means for near real-time monitoring of crop water status and requirements in agricultural and hydrological applications. Estimation of actual evapotranspiration (ETa) often requires thermal information; however, not every satellite is equipped with a thermal sensor, which limits the estimation of ETa. To address this limitation, here we propose a satellite-based ETa estimation model, OPTRAM-ET, based on the optical trapezoid model (OPTRAM) estimates of soil moisture and a vegetation index (VI). We applied the OPTRAM-ET model to Sentinel-2 and Landsat-8 satellite data and evaluated the model for ETa estimates using 16 eddy covariance flux towers in the United States and Germany with different landcover types, including agriculture, orchard, permanent wetland, and foothill forests. Next, OPTRAM-ET was compared with the conventional land surface temperature (LST)-VI model. The proposed OPTRAM-ET model showed promising performance over all the studied landcover types. In addition, OPTRAM-ET showed comparable performance to the conventional LST-VI model. However, since the OPTRAM-ET model does not need thermal data, it benefits from higher spatial and temporal resolution data provided by ever-increasing drone- and satellite-based optical sensors to predict crop water status and demand. Unlike the LST-VI model, which needs to be calibrated for each satellite image, a temporally-invariant region-specific calibration is possible in the OPTRAM-ET model. Therefore, OPTRAM-ET is substantially less computationally demanding than the LST-VI model.

Optimizing rate and time of nitrogen application for reducing nitrogen requirement and increasing productivity of wheat

As per 4Rs nutrient stewardship, the right timing and right rate of nitrogen (N) are two important attentions for profitable and sustainable crop production, particularly in the N deficient soil. The effectiveness of N utilization depends on the appropriate timing and amount of N application as per the crop demands at the critical stages of crop growth. The experiment was carried out at the experimental field of Agrotechnology Discipline, Khulna University, Bangladesh during the winter season of 2019-20 to investigate into the effect of schedule and rates of N application on wheat growth, yield and profitability. The experimental treatments comprised three application schedules (66% at sowing and 34% at the 3-leaf stage; 50% at 3-leaf, 30% at jointing and 20% at the booting stage; 50% at 6-leaf stage, 30% at jointing and 20% at the booting stage) and three nitrogen rates (120, 92 and 80 kg ha-1) with three replications. The yield attributes and yield of wheat were substantially affected by the schedule and rates of N application yet growth parameters were not significant. The highest grain yield, total dry matter, grains spike-1 and 1000-seed weight were achieved from the application of N @ 50% at 3-leaf, 30% at jointing and 20% at booting stages with 120 kg ha-1. Statistically similar results were also attained by the same application schedule with a reduced rat2.e of N (92 kg ha-1) due to proper distribution based on the crop requirement on different growth stages rather than the usual practice with a higher rate of N. The maximum net return (BDT 50687) and benefit-cost ratio (1.62) were found in the application of 92 kg ha-1 N in three splits @ 50% at 3-leaf, 30% at jointing and 20% at booting stages. The findings of this study revealed that the right application schedule reduces 25% N requirement and increases the grain yield of wheat.

ECONOMIC VALUE AND ECONOMIC ATTRACTIVENESS OF OATS IN THE CONTEXT OF THE DEVELOPMENT OF A NICHE PRODUCTION

The article reveals the economic value and economic attractiveness of oat production as one of the main niche grain crops. Considering the important role of oats, its advantages compared to other niche crops were outlined. It is substantiated that the economic attractiveness of its production is largely determined by its multifunctionality. The dynamics of oat production in Ukraine by category of farms was studied. The rating of oat production by regions of Ukraine was carried out, and the volume of its receipt at processing enterprises was considered. The dynamics of indicators of the economic efficiency of oat production in agricultural enterprises are analyzed and the prospects for the development of the production of niche grain crops are outlined. The authors prove that the use of niche crops in crop rotation allows to reduce the dominance of sunflower and rapeseed, the excessive cultivation of which greatly depletes the soil, and to diversify the existing grain-oil specialization of Ukrainian agriculture. The authors also reveal other advantages of growing niche crops (high profitability, diversification of production) and disadvantages (high cost of seed material and cultivation technologies, instability of demand for most niche crops, significant price fluctuations, uncertain amount of expected profit). It was established that an important feature of growing niche crops is the high resource intensity of their production. On the basis of the conducted research, we came to the conclusion that: oats are a high-value agricultural crop; oat grain production is potentially economically attractive; cultivation of niche grain crops is one of the most promising areas of development of small and medium-sized commodity producers, based on the fact that small farmers cannot compete with agricultural holdings in the production of traditional agricultural crops, so they should master the production of niche products; cultivation of niche crops will enable small enterprises to enter international markets and offer unique products.

Justification of Plants Water Demand in Conditions of Drip Irrigation

In the current work, a comprehensive methodology for the soil and climatic conditions of the Republic of Armenia has been developed to justify the water requirement/demand of plants in the case of drip irrigation. The proposed methodology enables to calculate the values of the individual components of the drip irrigation regime, and in practical terms, it was used to determine the water requirement of perennial plantations in the soil and climatic conditions of the Armavir and Kotayk marzes. Based on the obtained results, the crops drip irrigation norms/rates were mapped in the GIS environment. They can serve as a background for practical planning and justification of the drip irrigation water demand for various crops and contribute to the development of introduction rates of water-saving technologies in this field.

Econometric analysis of the influence of climate characteristics on the ecological condition of soils and the productivity of agricultural crops

An increase in air temperature causes water loss from irrigated areas due to evaporation. Such changes, in turn, increase the water demand of crops. High air temperature accelerates the natural decomposition of organic matter and causes a decrease in soil fertility. Furthermore, the probability of the spread of plant pests and diseases increases. This article presents an econometric analysis of the influence of climate characteristics on the ecological status of soils and the productivity of agricultural crops. The results of econometric modeling show that the constructed models can be used to forecast cotton yield for future periods. In Chimboy district (model 1), the influence of non-saline and weakly saline lands, groundwater level and relative air humidity on productivity was clearly demonstrated.

Mysuru Mallige-Heritage Crop of Mysuru: A Review

Jasmine being cultivated throughout India, its production/ largest area is concentrated in Tamil Nadu and Karnataka states. India stands next to Egypt and Morocco in Jasmine Concrete Production with >15 tons per annum. Modern Knowledge has accepted Jasmine as Persian origin, distribution pattern of 72 Jasminum spp. across India suggests, India may be the primary home which has its mention in the 500 BC Tamil literature and 7th to 3rd BCE Ramaynam mythological literature. In Karnataka, a number of Jasminum spp. are being cultivated throughout the state of which Mysuru Mallige, Udupi Mallige and Hadagali Mallige are being unique and are largely concentrated in the respective and adjoining districts. Government of India has registered these three jasmine cultivars with Geographical Indication tag under the Intellectual Property Rights. Though the demand for these GI crops is on increase, the area and production is declining slowly. Here is an attempt to compile the updated knowledge on genetic resources of Jasminum spp. with focus on the heritage crop of Mysuru- ‘Mysuru Mallige’.

Estimation of Crop Water Requirements and Irrigation Scheduling for Major Crops Grown in India's North-Eastern Region

The water demand of some agricultural crops grown in Assam was assessed in this research. To estimate the crop water requirements of potato, chili, and brinjal, the FAO-CROPWAT model was used. The climatic parameters like rainfall, solar radiation, wind speed, sun hours, relative humidity, minimum and maximum temperature were collected for 30 years from the Indian Meteorological Department (IMD) to estimate the crop water requirement (CWR). The reference evapotranspiration (ETo) was computed by using the Food and Agriculture Organization (FAO)-recommended Penman-Monteith method and was found to vary from 1.84 mm/day to 4.49 mm/day. The calculated ETo was further used to compute the CWR, the net irrigation requirement (NIR), and the gross irrigation requirement (GIR) to plan for irrigation application during the growing stages of the selected crops. The total CWR of potato, chili, and brinjal was estimated to be 260.6 mm, 262.1 mm, and 274.2 mm, respectively, and the total NIR of potato, chili, and brinjal sowed on the 1st of October was found to be 162.8 mm, 149.0 mm, and 167.2 mm, respectively, with an irrigation efficiency of 70%. In December, the CWR and NIR of potato and brinjal were found to be the highest. The month with the least effective rainfall (8.5 mm) was December. The findings of the study showed that efficient irrigation water management and irrigation scheduling can be achieved by using the CROPWAT model to maximize crop yield and minimize crop water stress.

Combined effects of landscape composition and agrochemicals on frog communities amid sugarcane-dominated agroecosystems.

Global demand for crops will continue increasing over the next few decades to cover both food and biofuel needs. This demand will put further pressure to expand arable land and replace natural habitats. However, we are only beginning to understand the combined effects of agrochemicals and land-use change on tropical freshwater biodiversity. In this study, we analyzed how pond-dwelling anuran larvae responded to pond characteristics, landscape composition, and agrochemical contamination in a sugarcane-dominated agroecosystem in Brazil. Then we used an information theoretical approach with generalized linear models to relate species richness and abundance to predictor variables. The variation in tadpole abundance was associated with both agrochemical concentration (e.g., ametryn, diuron, and malathion) and landscape variables (e.g., percentage of forest, percentage of agriculture, and distance to closest forest). The relationship between species abundance and agrochemicals was species-specific. For example, the abundances of Scinax fuscovarius and Physalaemus nattereri were negatively associated with ametryn, and Dendropsophus nanus was negatively associated with tebuthiuron, whereas that of Leptodactylus fuscus was positively associated with malathion. Conversely, species richness was associated with distance to forest fragments and aquatic vegetation heterogeneity, but not agrochemicals. Although we were unable to assign a specific mechanism to the variation in tadpole abundance based on field observations, the lower abundance of three species in ponds with high concentrations of agrochemicals suggest they negatively impact some frog species inhabiting agroecosystems. We recommend conserving ponds near forest fragments, with abundant stratified vegetation, and far from agrochemical runoffs to safeguard more sensitive pond-breeding species.

Perennial Crops Can Compensate for Low Soil Carbon Inputs from Maize in Ley-Arable Systems.

(1) Background: Soil organic carbon (SOC) in agricultural soils plays a crucial role in mitigating global climate change but also, and maybe more importantly, in soil fertility and thus food security. Therefore, the influence of contrasting cropping systems on SOC not only in the topsoil, but also in the subsoil, needs to be understood. (2) Methods: In this study, we analyzed SOC content and δ13C values from a crop rotation experiment for biogas production, established in southern Germany in 2004. We compared two crop rotations, differing in their proportions of maize (0 vs. 50%) and perennial legume-grass leys as main crops (75 vs. 25%). Maize was cultivated with an undersown white clover. Both rotations had an unfertilized variant and a variant that was fertilized with biogas digestate according to the nutrient demand of crops. Sixteen years after the experiment was established, the effects of crop rotation, fertilization, and soil depth on SOC were analyzed. Furthermore, we defined a simple carbon balance model to estimate the dynamics of δ13C in soil. Simulations were compared to topsoil data (0-30 cm) from 2009, 2017, and 2020, and to subsoil data (30-60 cm) from 2020. (3) Results: Crop rotation and soil depth had significant effects, but fertilization had no effect on SOC content and δ13C. SOC significantly differed between the two crop rotations regarding δ13C in both depths but not regarding content. Annual enrichment in C4 (maize) carbon was 290, 34, 353, and 70 kg C ha-1 per maize year in the topsoil and subsoil of the unfertilized and fertilized treatments, respectively. These amounts corresponded to carbon turnover rates of 0.8, 0.3, 0.9, and 0.5% per maize year. Despite there being 50% maize in the rotation, maize carbon only accounted for 20% of the observed carbon sequestration in the topsoil. Even with pre-defined parameter values, the simple carbon model reproduced observed δ13C well. The optimization of model parameters decreased the carbon use efficiency of digestate carbon in the soil, as well as the response of belowground carbon allocation to increased aboveground productivity of maize. (4) Conclusions: Two main findings resulted from this combination of measurement and modelling: (i) the retention of digestate carbon in soil was low and its effect on δ13C was negligible, and (ii) soil carbon inputs from maize only responded slightly to increased above-ground productivity. We conclude that SOC stocks in silage maize rotations can be preserved or enhanced if leys with perennial crops are included that compensate for the comparably low maize carbon inputs.

An In-Depth Assessment of the Drivers Changing China’s Crop Production Using an LMDI Decomposition Approach

Over the last decades, growing crop production across China has had far-reaching consequences for both the environment and human welfare. One of the emerging questions is “how to meet the growing food demand in China?” In essence, the consensus is that the best way forward would be to increase crop yield rather than further extend the current cropland area. However, assessing progress in crop production is challenging as it is driven by multiple factors. To date, there are no studies to determine how multiple factors affect the crop production increase, considering both intensive farming (using yield and multiple cropping index) and large-scale farming (using mean parcel size and number of parcels). Using the Logarithmic-Mean-Divisia-Index (LMDI) decomposition method combined with statistical data and land cover data (GlobeLand30), we assess the contribution of intensive farming and large-scale farming changes to crop production dynamics at the national and county scale. Despite a negative contribution from MPS (mean parcel size, ), national crop production increased due to positive contributions from yield (), MCI (multiple cropping index, ), as well as NP (number of parcels, ). This allowed China to meet the growing national crop demand. We further find that large differences across regions persist over time. For most counties, the increase in crop production is a consequence of improved yields. However, in the North China Plain, NP is another important factor leading to crop production improvement. On the other hand, regions witnessing a decrease in crop production (e.g., the southeast coastal area of China) were characterized by a remarkable decrease in yield and MCI. Our detailed analyses of crop production provide accurate estimates and therefore can guide policymakers in addressing food security issues. Specifically, besides stabilizing yield and maintaining the total NP, it would be advantageous for crop production to increase the mean parcel size and MCI through land consolidation and financial assistance for land transfer and advanced agricultural infrastructure.

A pragmatic approach to the combined effect of climate change and water abstraction on Lake Ziway water balance, Ethiopia

AbstractClimate change and ongoing human activity have been threatening Ethiopia's Lake Ziway's water balance. However, few studies have been conducted to investigate the combined effects of climate change and water withdrawal on the lake's water balance using climate change and water withdrawal for irrigation. We used high-resolution multiple climate models and Representative Concentration Pathways (RCP) scenarios to assess the impact of climatic variables for two future periods: 2021–2050 and 2051–2080. Rainfall and temperature data biases were corrected using power transformation and variance scaling methods, respectively. The Hydrologiska Byråns Vattenbalansavdelning (HBV) hydrological model was employed to simulate surface inflow into Lake Ziway from the Meki and Katar sub-catchments. The FAO CROPWAT model was used to estimate the irrigation water demand of major crops grown in the study area. The results indicate that future temperatures and wet season runoff levels are expected to rise. Under the worst climate change scenario, climate change and water withdrawal from the lake for agriculture may cause the lake level to drop by 25 cm per year, resulting in a 10 km2 surface area and 101 Mm3 volume reductions. Therefore, implementing preventive measures, proper planning and careful monitoring of lake water use is advised.

Solar Photovoltaic Pump-operated Micro-irrigation Systems: A Comprehensive Review

Increasing energy scarcity has compelled the agricultural and energy engineers to look for alternative renewable energy sources to sustain irrigated agriculture. Among the renewable energy options available for irrigation, adoption of solar photovoltaic (PV) energy is growing at faster rate all around the world. Also, the micro-irrigation (MI) system is widely accepted as the most efficient irrigation method. Integrated application of solar PV and MI system is one of the most energy- and water-efficient solution to agriculture, and is gaining popularity among the farmers. However, the intermittent supply of power from the solar PV system hinders the performance of directly connected MI system. It demands additional costly energy and water storage options for hassle-free operation. Systematic integration of PV and MI system is required to avoid storage options and to meet energy and water demand of crops for universal agricultural applications. This manuscript is an attempt to present a comprehensive review of literature reported in this area in the past two decades.

Agro-virtual water trade in relation to water availability and attributes of crop import of Lungnyi Gewog, Bhutan

Virtual Water Trade is the product of Specific Water Demand and quantity of a commodity traded in tons. The water availability, water utility patterns, attributes of agricultural products imports, and quantity of 4 selected crops traded were collected through a questionnaire survey with a systematic circular design. The Specific Water Demand of crops was collected from published FAO guidelines and data was analyzed using MS-Excel and Statistical Package for Social Science (SPSS). The Net Virtual Water Trade was calculated using MS Excel. The study showed positive NVWT with higher virtual water export than an import for the study area. The independent sample t-test showed a significant difference between NVWT of farmers that has and that do not have enough water for agriculture t¬ (88) =3.129, p=0.002. The Pearson Chi-Square test showed no significance in the relationship between attributes of import of agri-products and availability of water resources in the Gewog; X2 (4, N=90) = 63.68, p=0.000. The study revealed a strong correlation between household size and VWI of apple and rice and VWE of apple, potato, chilli, and rice at p

Ethnic crop consumption and marketing in the Eastern United States: Trends and prospects

The population demographics of the eastern U.S has changed in recent years with an increase in immigrants, particularly of Asian and Hispanic origins. This trend motivated the identification of foods preferred by these ethnic communities in 16 states in the region and Washington, D.C., focusing on greens and herbs. Over 100 ethnic greens and herbs were identified as being preferred food choices, from which 40 were selected for further study, representing 10 crops important to four ethnicities: Asian Indian, Chinese, Mexican, and Puerto Rico. Bulletin board focus group and telephone survey participants responded to questions regarding their consumption in 2010. The relevant information was collected to assess retail sales for each crop for each of the four ethnic groups. Results demonstrated that the ethnic crop demand in the eastern U.S is significant, and the prospects for future growth are promising as the population of ethnic consumers in the region is projected to continue to grow.

Hydraulic calculation lateral in drip irrigation

Drip irrigation systems are widely used worldwide to satisfy the water demand of agricultural crops. It is known that drip irrigation technology has a number of other advantages, such as intensive irrigation, automation, and water economical benefits. The methods which is available in hydraulics are widely used in the calculation of drip irrigation design. One of the most important issues in the drip irrigation system is the correct estimation of the discharge coming out of the drippers. As known from hydraulic calculations, it is necessary to take into account the pressure when determining the discharge coming out of the emitters. It should also be noted that discharge from emitters has a special effect on pressure losses in drip irrigation systems. The article presents the results of the research conducted in natural field conditions on the assessment of hydraulic processes in drip irrigation systems. As an object of research, the cultivated field of the “Sharifjan oglu Akhmadjon” farm in Rishton district, Fergana region was selected. The results of measurement work at 36 points of the research object are highlighted. As a result of the conducted research, recommendations for determining discharge in irrigation pipes were developed.

Multi-objective planning for food production in a mountainous region: Strategic land utilization for meeting food demand and economic revitalization

• Multi-objective planning leads to increased food production in a mountainous region • Land grading criteria are used to conserve crop diversity with limited land • Land accessibility analysis suggests potential for expandable crop production • Surplus horticultural production showed immense economic revitalization potential The mountainous landscapes and significant decline of predominate industries have made the North Central Appalachian (NCA) region vulnerable to economic shocks. Given the rugged terrain that hinders large-scale industrialization, community-supported food production can be a sustainable solution to help meet food demand and revitalize regional economy. This study evaluated the potential of strategic utilization of arable land in a mountainous region to increase niche crops production and revenue. Using West Virginia as a study area, current food production shortages were estimated to be -47% to -100% for all 30 crops. A novel multi-objective planning function that considers land slope, crop diversity, yield and sale price was developed and applied to reallocate existing and expandable arable lands for increased food production. Accessibility, a numeric measure determined by the land slope and traversable road networks, was used to delineate availability of arable lands, and the accessibility values (0.816-0.999) of the expandable arable land suggests high accessibility. Results showed that demand for horticultural crops can be extensively met (potential/demand = ∼39) by restructuring the cropland; whereas field crop gaps can be slightly ( i.e ., 0.6%) reduced with the addition of expandable land. The analyses yielded a surplus production of horticultural foods while increasing crop diversity, and showed immense potential for economic revitalization. The methodology developed in this study and the results could be used to leverage regional policymaking to significantly reduce food shortage and to enhance economic revival in the NCA and similar regions.

Adaptive strategies of plants to conserve internal phosphorus under P deficient condition to improve P utilization efficiency.

Phosphorus (P) is one of the limiting factors for plant growth and productivity due to its slow diffusion and immobilization in the soil which necessitates application of phosphatic fertilizers to meet the crop demand and obtain maximum yields. However, plants have evolved mechanisms to adapt to low P stress conditions either by increasing acquisition (alteration of belowground processes) or by internal inorganic P (Pi) utilization (cellular Pi homeostasis) or both. In this review, we have discussed the adaptive strategies that conserve the use of P and maintain cellular Pi homeostasis in the cytoplasm. These strategies involve modification in membrane lipid composition, flavanol/anthocyanin level, scavenging and reutilization of Pi adsorbed in cell wall pectin, remobilization of Pi during senescence by enzymes like RNases and purple acid phosphatases, alternative mitochondrial electron transport, and glycolytic pathways. The remobilization of Pi from senescing tissues and its internal redistribution to various cellular organelles is mediated by various Pi transporters. Although much efforts have been made to enhance P acquisition efficiency, an understanding of the physiological mechanisms conserving internal Pi and their manipulation would be useful for plants that can utilize P more efficiently to produce optimum growth per unit P uptake.

Evaluation of Controlled Release Fertilizer on Bulb Yield, Nutrient Content, and Storage Quality of Overwintering Intermediate-Day Onions

Controlled release fertilizer (CRF) can delay its availability for plant uptake and increase fertilizer use efficiency, which might be useful for overwintering onion (Allium cepa L.) which has a growing season of 7 to 8 months. The study was performed to evaluate the effect of CRF on bulb yield, nutrient content, and storage quality of intermediate-day onions in onion growers’ fields during the 2013/2014 and 2014/2015 growing seasons. The formulation of CRF used was 18N-3.1P-7.5K, and as an N source, 50% polymer-coated urea-N and 50% urea-N plus diammonium phosphate-N were blended. Treatments included CRF 25%, CRF 50%, CRF 100%, or CRF 150% based on the soil test recommended N rate. Separated NPK fertilizers of single application (NPK once), three-split application (NPK 3-split) and non-fertilized plot were checks. Soil NO3-N content in all CRF treatments and NPK once peaked at 133 days after transplanting. Marketable bulb yields for NPK once and CRF 150% was 66.12 Mg ha-1 and 65.67 Mg ha-1, respectively, on a 2-year average, which were not significantly greater than CRF 50%, CRF 100%, and NPK 3-split. Most nutrient uptakes in the bulb were not different among all treatments except for no fertilization. Apparent nutrient recovery of CRF 25% was 32.5% in N, 20.9% in P, and 76.1% in K on a 2-year average, approximately twice that of CRF 100%. Total flavonoids content was higher in CRF 25% than in other treatments. The 50% reduced CRF rate based on the soil test recommended N rate should satisfy crop demand of available nutrients when electric conductivity was more than 1.5 dS m-1 and organic matter was 35 g kg-1 in preplant soil.Comparison of bulb yield characteristics of onion as affected by application rates of controlled release fertilizer (CRF) and application methods of NPK fertilizer. Treatments Marketable yield (Mg ha-1) Unmarketable yield (Mg ha-1) Stand reduction (%) Large† Medium Small Total 2013/2014 CRF 25%‡ 52.98 ns§ 27.48 ns 1.26 ns 81.73 ns 1.29 ns 2.8 ns CRF 50% 62.67 22.44 0.67 85.79 0.69 2.3 CRF 100% 67.81 19.62 0.45 87.87 0.94 4.6 CRF 150% 68.31 22.00 0.58 90.89 0.55 1.9 NPK once 69.16 18.81 1.49 89.47 1.21 2.8 NPK 3-split 68.08 19.13 0.50 87.71 0.80 5.1 No fertilization 60.71 22.08 1.49 84.29 0.56 5.6 2014/2015 CRF 25% 3.28 ns 24.41 ns 10.37 b 38.07 ns 0.80 ns 7.90 ab CRF 50% 2.87 29.07 8.96 b 40.89 0.48 8.94 a CRF 100% 2.10 22.69 10.28 b 35.07 0.97 8.31 a CRF 150% 3.16 27.14 10.14 b 40.44 0.72 6.30 ab NPK once 4.43 28.24 10.10 b 42.77 1.02 6.83 ab NPK 3-split 2.33 28.68 10.88 b 41.88 0.68 4.88 b No fertilization 0.67 14.92 17.18 a 32.78 0.33 7.17 ab F-test Year (Y) ** ns ** ** ns ns Fertilizer (F) ns ns ** ns ns ** Y × F ns ns ** ns ns ns †Size categories in bulb diameter: large (≥8.0 cm), medium (≥6.0 and <8.0 cm), small (≥4.0 and <6.0 cm), and cull (<4.0 cm).‡CRF 25%, 50%, 100% and 150% rates based on soil test recommended N rate; NPK once = single application of N, P and K with 100% rate based on soil test recommended N, P and K rate; NPK 3-split = basal and 2-split applications of N, P and K.§Fisher’s protected least significant difference (p ≤ 0.05). ns, *, **: not significant or significant at p ≤ 0.05, p ≤ 0.01.

Development of a LoRaWAN IoT Node with Ion-Selective Electrode Soil Nitrate Sensors for Precision Agriculture

Crop productivity is highly dependent on the availability of soluble nitrogen (N), e.g. nitrate, in soil. When N levels are low, fertilisers are applied to replenish the soil's reserves. Typically the timing of these applications is based on paper-based guidance and sensor-based measurements of canopy greenness, which provides an indirect measure of soil N status. However this approach often means that N fertiliser is applied inappropriately or too late, resulting in excess N being lost to the environment, or too little N to meet crop demand. To promote greater N use efficiency and improve agricultural sustainability, we developed an Internet of Things (IoT) approach for the real-time measurement of soil nitrate levels using ion-selective membrane sensors in combination with digital soil moisture probes. The node incorporates state-of-the-art IoT connectivity using a LoRaWAN transceiver. The sensing platform can transfer real-time data via a cloud-connected gateway for processing and storage. In summary, we present a validated soil sensor system for real-time monitoring of soil nitrate concentrations, which can support fertiliser management decisions, improve N use efficiency and reduce N losses to the environment.