Site-specific Nutrient Management Research Articles

Spatial variability of soil nutrients under sugarcane cropping system in semi-arid tropics of western India using geostatistics and GIS

The present study aimed to assess the spatial variability and mapping of soil macro and micro nutrients under sugarcane cropping system in semi-arid tropics of western Maharashtra using geostatistics and Geographic Information System (GIS). Totally 205 surface soil samples were collected at 200 x 200 m interval using the grid sampling technique in three distinct landforms. In order to assessand mapping the spatial variability of soil fertility properties, geo-statistical analysis was carried out by using best fitted models in GIS. The geostatistical analysis shows that Standardized Root Mean Square Error (RMSSE) for almost all variables expect for CaCO3 (0.96) and Mn (0.97) were close to one, which indicates a good prediction. Results showed that the available N and P varied from 125.4 to 216.4 and 7.2 to 19.7 kg ha−1, respectively, whereas, available K was ranged from 278.7 to 975.2 kg ha−1. The available Mn and Cu status of soils were sufficient with 4.12 to 21.12 and 1.57 to 4.68 mg kg−1, respectively. However, significant portion of the study area showed deficiency of available Zn. The assessed spatial variability of various soil nutrients helps in site-specific nutrient management and crop planning decisions to improve sugarcane productivity.

Distribution of Micronutrients in Selected Pedons of Sugarcane Growing Vertisols in Northern Karnataka State of India

Micronutrients deficiency is a major limiting factor for increasing yield and productivity of major crops in India. Recent findings of multiple micronutrients interactions have evidenced the indispensable role played by micronutrients in plant nutrition. Though they are needed in smaller quantities, however, their availability in the Right amount, at the Right time, and for the Right crop has been a major limiting factor for improving the productivity and yield of Sugarcane in northern Karnataka state of India. This study was conducted to assess the level of Boron (B), Copper (Cu), Iron (Fe), Manganese (Mn) and Zinc (Zn) deficiencies in Sugarcane growing Vertisols of six micro-watersheds in northern Karnataka. The six selected micro-watersheds were intensively traversed and six representative pedons of standard dimensions were dug and horizon-wise soil samples collected and analyzed for various micronutrients using standard analytical procedures. Based on the optimum critical levels of micronutrients, B, Fe and Zn were deficient, ranging from 0.15 - 0.64, 1.23 - 5.92 and 0.11 - 0.64 mg⋅kg−1 respectively while Cu and Mn were in excess, ranging from 1.54 - 7.62 and 1.22 - 7.03 mg⋅kg−1 respectively. The distribution of B, Fe and Zn were inversely proportional to soil depth whereas that of Cu and Mn were irregular, which is an indication of the influence of pedoturbation in these soils. With the current rate of agricultural intensification, unbalanced fertilizer application, depletion of nutrients and no replenishment by smallholders, the results reveal that the current deficiency levels may increase further if appropriate and timely actions are not taken. We therefore recommend the use of site-specific nutrient management, balanced fertilizer application and good agronomic practices. These can enhance nutrient use efficiency in the study area.

Response of maize yield to nitrogen, phosphorus, potassium and sulphur rates on Andosols and Nitisols in Ethiopia

Summary The use of fertilizers in balanced and adequate amounts is a prerequisite for increasing crop productivity and production. Unbalanced plant nutrient management continues to be a major factor contributing to low maize (Zea mays L.) yields due to lack of information on the dose–responses to macronutrients on different soil types in Ethiopia. This study was carried out to quantify maize yield response and agronomic efficiency of varying application rates of nitrogen (N), phosphorus (P), potassium (K) and sulphur (S) under balanced application of other nutrients across two soil types in Ethiopia. Field trials were set up on 29 farmers’ fields in four districts of Oromia and Southern Nations, Nationalities and Peoples Region (SNNPR) for three consecutive cropping seasons (2014–2017). The treatments consisted of six rates of N, P and S each and eight rates of K combined with balanced application of the remaining macronutrients, zinc (Zn) and boron (B). The treatments were laid out in randomised complete blocks design with three replicates per farm. Using nutrient dose–response modelling, the agronomic optimum rates of N, P, K and S were estimated at 46, 40, 17 and 10 kg ha−1 on Nitisols, with balanced application of the other nutrients. On Andosols, the optimum rates of N, P and S were estimated at 184, 20 and 30 kg ha−1, respectively, but the optimum K rate could not be estimated. The predicted maximum yields obtained with balanced nutrient application were lower on Andosols (3397–3640 kg ha−1) than on Nitisols (4630–6094 kg ha−1). Using the Mitscherlich dose–response model, the percentage deficiencies of N, P, K and S were estimated to be 1.3–3.3 times more on Nitisols than Andosols. Consequently, agronomic efficiencies of N, P, K and S were significantly lower on Andosols than on Nitisols. It is concluded that balanced application of 46 kg N ha−1, 40 kg P ha−1, 17 kg K ha−1, 10 kg ha−1 S, 2 kg Zn ha−1 and 0.5 kg B ha−1 could be recommended for maize on Nitisols in the study area. Although this recommendation may also apply to Andosol, further research is needed as the productivity of Andosols appears to be limited by constrains other than N, P, K, S, Zn and B. We also recommend a shift from the blanket fertilizer recommendations to site-specific nutrient management based on good understanding of the variations in crop response with soil type and agroecology and appropriate soil and plant analyses.

Effect Of Plant Densities And Fertilizer Rates On Grain Yield Of Spring Maize In Inner Terai Condition

To improve the yield of spring season maize in the inner terai of Nepal, the effect of increasing fertilizer levels for increasing planting densities on growth, yield attributes, and yield of open-pollinated maize variety were analyzed through the field experimentation in 2019. The treatments included factorial combinations of three planting densities, (a) 55556/ha, (b) 66667/ha, and (c) 83333/ha; and four fertilizers levels (research-based recommendation i.e., 120:60:40 N:P2O5:K2O kg/ha, 144:72:48 N:P2O5:K2O kg/ha, 180:90:60 N:P2O5:K2O kg/ha, and site-specific nutrient management (SSNM) based nutrient expert model recommendation i.e., 140:40:40 N:P2O5:K2O kg/ha) arranged in a split-plot design with three replications. Data on growth, yield attributes, and yield were analyzed by using R Studio. Growth was higher under the highest planting density and higher fertilizer levels applied treatments. The higher (p<0.05) heat use efficiency was recorded under the highest planting density and the higher levels of fertilizer application. The final plant population was 5.33% lower in the plant density of 55556/ha, 8.8 and 15.7% lower respectively for plant densities of 66667/ha and 83333/ha. Both the barrenness and sterility percentage were higher (p<0.05) for the highest planting densities and the lowest for the lowest plant density. Higher (p<0.05) number of kernels per cobs were recorded in the lowest plant density and the highest amount of fertilizer application. For the lowest and the highest plant densities, the leaf area index increased the grain yield whereas longer grain filling duration and less amount of barrenness and sterility increased (p<0.05) the grain yield for all plant densities. The final number of plant populations was the most important parameter to increase (p<0.05) the yield under lower plant density whereas the number of kernels per row or cob was the most important attribute to increase (p<0.05) the yield of maize under higher plant density. Due to a higher (p<0.05) number of final plant populations and comparable yield attributes, the grain yield of the highest planting density was significantly (p<0.05) higher. From the significant (p<0.05) quadratic response of plant density on the grain yield, a density of 102,950 /ha was estimated as optimum. The increased in amount of fertilizers (144:72:48 N:P2O5:K2O kg/ha, 180:90:60 N:P2O5:K2O kg/ha) gave higher grain yield. The plant densities of 66667/ha and 83333/ha were better whereas the present recommended dose of N: P2O5:K2O should be increased or need-based SSNM must be adopted to obtain the more profits from open-pollinated spring maize under the central inner Terai.

Site Specific Nutrient Management Options for Achieving Higher Yields in Cotton and Chickpea under Rainfed Condition

A study was undertaken to delineation of spatial variability of soil fertility status in order to prepare soil available nutrient maps for improved productivity in different crops grown in the study area of Kurnool revenue division in Kurnool district of Andhra Pradesh state using remote sensing and GIS techniques. The Knowledge of spatial-variability is critical for site specific nutrient management in soil fertility to obtain higher yields. Soil sample (350) were collected from surface from 350 selected sites for preparing precise digital maps using point, line and polygon tools of the Geographic Information System (GIS) with ArcGIS software 10.3 was used for database creation and for creating the union of various thematic maps. The spatial variability maps were generated and delineated into different zones for N, P and K. Soil available Nitrogen, Phosphorus and Potassium spatial variability values generated from the thematic maps of Kurnool division were used to establish fertilizer recommendations for cotton in kharif and Chickpea in rabi during 2018-19 seasons. The recommended doses of Nitrogen (RDN) that worked for cotton were 401 to 450, 351 to 400, > 450 and < 350 kg ha-1 for the areas with Nitrogen availability of 140 to 210, 210 to 280, <140 and > 280 kg/ha, respectively. The Phosphorous fertilizer recommendation for soils with available P of < 30 kg/ha and > 30 kg/ha was figured out as > 250 kg ha-1 and < 250 kg ha-1, respectively. For soil available Potassium recorded 230 to 560, < 230 and > 560 kg/ha, the K recommendation was figured out as 301 to 400, > 401 and < 300 kg/ha, respectively. Recommended doses of Nitrogen (RDN) was worked out for chickpea were 51 to 75, > 76 and < 50 kg/ha for the areas with available N ranges of 184 to 280, < 184 and > 280 kg/ha, respectively. The Phosphatic fertilizer recommendation for soils of available P of < 23.5 and 23.5 to 40 kg/ha was figured out as > 200 kg/ha and 171 to 200 kg/ha, respectively. For the soil available potassium recorded 253 to 412, 413 to 570, < 253 and > 570 kg/ha, the K recommendation was figured out as 66 to 100, 31 to 65, > 100 and < 30 kg/ha, respectively.

Dose-response models to guide site-specific nutrient management and lessons for fertiliser trial design in sub-Saharan Africa

Summary Optimisation of fertiliser use and site-specific nutrient management are increasingly becoming critical because of the growing need to balance agricultural productivity with the growing demand for food and environmental concerns. Trials to determine responses of crops to fertilisers have been widely conducted in sub-Saharan Africa (SSA) with increasing emphasis on the development of economically optimum rates (EORs). Computation of EORs depends on accurate estimation of both the optimum nutrient rate and the agronomic maximum yield response; however, estimation of nutrient-response parameters and EORs is beset by a number of problems. Therefore, the objectives of this paper were to (1) point out common problems in the development and use of nutrient dose-response models and (2) provide corrective measures to facilitate future trial design and data analysis. This review outlines the underlying assumptions, strengths and limitations of the various response functions in order to facilitate informed choices by practitioners. Using specific examples, it also shows that (1) the commonly used trial designs do not allow examination of interactions between two or more nutrients and (2) trial designs with ≤5 nutrient levels and wide spacing between the levels result in large uncertainty in dose-response parameters. The key recommendations emerging from the review are as follows: (1) factorial designs and response surface models should be used more widely to address interactions between nutrients; (2) a minimum of six carefully spaced nutrient levels should be used to correctly estimate dose-response parameters; and (3) when locating field trials, Reference Soil Groups and cropping history should be carefully considered to produce site-specific EORs.

Improving Nitrogen Use Efficiency—A Key for Sustainable Rice Production Systems

Fertilizer use and genetic improvement of cereal crops contributed to increased yields and greater food security in the last six decades. For rice, however, fertilizer use has outpaced improvement in yield. Excess application of nutrients beyond crop needs, especially nitrogen (N), is associated with losses to the environment. Environmental pollution can be mitigated by addressing fertilizer overuse, improving N use efficiency, while maintaining or improving rice productivity and farmers' income. A promising approach is the site-specific nutrient management (SSNM), developed in the 1990s to optimize supply to meet demand of nutrients, initially for rice, but now extended to other crops. The SSNM approach has been further refined with the development of digital decision support tools such as Rice Crop Manager, Nutrient Expert, and RiceAdvice. This enables more farmers to benefit from SSNM recommendations. In this mini-review, we show how SSNM can foster sustainability in rice production systems through improved rice yields, profit, and N use efficiency while reducing N losses. Farmer adoption of SSNM, however, remains low. National policies and incentives, financial investments, and strengthened extension systems are needed to enhance scaling of SSNM-based decision support tools.

Effect of nutrient management practices and planting density on yield and nutrient uptake by hybrid maize (Zea mays)

A field experiment was conducted at Crop Research Station, Bahraich (Uttar Pradesh) during Rabi season of 2015-16 and 2016-17 to study the effect of plant geometry and nutrient management practices on the performance of maize hybrids. Two maize Hybrids (H and 9682, Dekalb 900) were located in main plots, two plant geometry (60 x 20 cm and 50 x 20 cm). in subplot and three nutrient management practices viz RDF (200:60:60 kg NPK ha-1), STCR (250:50:50 kg NPK ha-1), SSNM (225:60:80 kg NPK ha-1) in sub–sub plot in split plot design with three replications. Results revealed that the higher maize yield (6804 kg ha-1 ) was recorded in maize hybrid Dekalb 900. The maximum grain (6693 kg ha-1) and stover yield (7391 kg ha-1) were recorded under the plant geometry of 60 x 20 cm and SSNM (225:60:80 kg NPK ha-1). The yield attributing characters as well as yield of the crop was benefited under hybrid Dekalb 900, Plant geometry of 60 x 20 cm and site specific nutrient management practice. The higher net return of Rs. 69680, Rs.71323 and Rs. 73483 ha-1 were recorded with maize Hybrid Dekalb 900, plant geometry of 60x20 cm and SSNM practice, respectively. The highest plant nutrients uptake of N (159 kg ha-1), P (33.9 kg ha-1) and K (85.1 kg ha-1 ) were found with (SSNM).

Stability and Adaptability of Maize Hybrids for Precision Crop Production in a Long-Term Field Experiment in Hungary

Sustainability is one of the main components of precision farming that will lead to food security and production resources for current and future generations. The selection of suitable hybrids and fertilizers is among the methods that can directly influence sustainable agriculture and economic efficiency at the farm level, providing accurate site-specific nutrient management strategies for yield maximization. This experiment included two fertilizer sources in ten maize hybrids in four replications for three consecutive years (2018–2020). The experiment was carried out at the Látókép Crop Production Experimental Site of the University of Debrecen, Hungary. The results of the ANOVA showed that genotype, year, and fertilizer levels had various effects on grain yield, oil, protein, and starch content. FAO340 had maximum grain yield on different fertilizers (NPK and N), and FAO350 had maximum protein content. To gain the best performance and maximum yield of maize on protein and oil, FAO350 is recommended for protein and FAO340 for oil content. The parameters of grain yield, oil content, protein content, and starch content affected by NPK fertilizer provide the stability of grain yield parameters. FAO360, FAO420, and FAO320 hybrids had their maximum desirable N fertilizer doses and NPK fertilizer stability in this research. These results indicate that FAO360, FAO420, and FAO330 hybrids had their maximum potential yield in different fertilizer and environmental conditions. Based on this multi-year study, the complete NPK fertilizer with 150 kg/ha nitrogen, 115 kg/ha potassium, 135 kg/ha phosphorus is recommended to be used on maize hybrids.

Nutrient Expert: An ICT Tool of Agricultural Institution for Economic Development of Maize Growing Farmers in Jharkhand

Background: Nutrient expert is a computer based software for site specific nutrient management which advocates location specific requisite quantities of nutrients application in crops to achieve targeted yield by narrowing down the difference between actual yield and potential yield. The current study aimed to study efficiency of nutrient expert over other fertilizer recommendations on maize varieties. Methods: An experiment was conducted to test six maize varieties against state fertilizer recommendation, nutrient expert based fertilizer recommendation and farmers’ fertilizer practice during Kharif season of 2017. The nutrient expert software was used to calculate dose of nutrient expert for targeted yield of 8 t/ha. Result: The result indicated significant improvement by nutrient expert based fertilizer recommendation for grain yield, stover yield, net return and nutrient uptake of nitrogen, phosphorus and potassium in grain and stover of maize. Among maize varieties, CMH-08-350 recorded significantly higher grain yield, stover yield, net return and nutrient uptake of maize than PMH-3, CMH-08-287, PMH-1 and HQPM-1.

Evaluation of spatial spreading of phyto-available sulphur and micronutrients in cultivated coastal soils.

Understanding the spatial spreading patterns of plant-available sulphur (S) (AS) and plant-available micronutrients (available zinc (AZn), available iron (AFe), available copper (ACu), available manganese (AMn) and available boron (AB)) in soils, especially in coastal agricultural soils subjected to various natural and anthropogenic activities, is vital for sustainable crop production by adopting site-specific nutrient management (SSNM) strategies. We studied the spatial distribution patterns of AS, AZn, AFe, ACu, AMn, and AB in cultivated soils of coastal districts of India using geostatistical approaches. Altogether 39,097 soil samples from surface (0 to 15 cm depth) layers were gathered from farm lands of 68 coastal districts. The analysis of soil samples was carried out for soil pH, electrical conductivity (EC), soil organic carbon (SOC) and AS, AZn, AFe, ACu, AMn, and AB. Soil pH, EC and SOC varied from 3.70 to 9.90, 0.01 to 7.45 dS m-1 and 0.02 to 3.74%, respectively. The concentrations of AS, AZn, AFe, ACu, AMn, and AB varied widely in the study area with their corresponding mean values were 37.4±29.4, 1.50±1.53, 27.9±35.1, 2.14±1.74, 16.9±18.4 and 1.34±1.52 mg kg-1, respectively. The coefficient of variation values of analyzed soil parameters varied from 14.6 to 126%. The concentrations of AS, AZn, AFe, ACu, AMn, and AB were negatively and significantly correlated with soil pH and positively and significantly correlated with SOC. The geostatistical analysis indicated stable, Gaussian and exponential best-fit semivariogram models with moderate to strong spatial dependence for available nutrients. The generated spatial spreading maps revealed different distribution patterns for AS, AZn, AFe, ACu, AMn, and AB. There were variations in spatial spreading patterns of AS, AZn, AFe, ACu, AMn, and AB in east- and west-coastal area. About 62, 35, 12, 0.4, 23 and 45% of the study area had deficiency of AS, AZn, AFe, ACu, AMn, and AB, respectively. The spatial spreading maps will be highly useful for SSNM in the cultivated coastal soils of the country. This study could also be used as a base for assessing spatial spreading patterns of soil parameters in cultivated coastal areas of other parts of the world.

Assessment of Nutrient Expert ®-Hybrid maize model on productivity and profitability of winter maize in Terai region of eastern Nepal

Inadequate, unscientific, and lack of optimum utilization of fertilizer management devoid of site-specific nutrient management have been the significant constraints of maize (Zea mays L.) production in Nepal. Therefore, a multi-locational farmers' field was planned and executed at two VDCs of Morang district in the Terai region of Nepal from December 2015 to May 2016. Nutrient Expert (NE) and Farmer's Fertilizer Practices (FFP) treatments were imposed in a randomized complete block design (RCBD) with twenty replications. The research explored highly significant results in terms of plant number m−2, cob numbers m−2, cob length, kernel rows cob−1, kernels kernel row−1, test weight, grain, stover, and biological yields and harvest index. NE showed the highest yield (8.06 tons ha -1) among the two treatments tested than FFP (4.52 tons ha −1). While comparing net revenue, NE-based fertilizer recommendation gave the significantly higher (NRs.151.116 thousand ha −1 equivalent to $1281 ha −1) result than FFP (NRs.84.834 thousand ha−1 equivalents to $707). The result suggests adopting NE practices to minimize the yield gaps and increase the productivity of maize in Morang and adjoining agro-climatic conditions of eastern Terai, Nepal.

Effect of nutrient management on yield, economics, water and energy use efficiency of maize (Zea mays) under conservation agriculture based maize-wheat (Triticum aestivum) system

A field experiment was conducted under long-term conservation agriculture (CA)-based maize (Zea mays L.)-wheat (Tricum aestivum L.)-mungbean (MWMb) system at ICAR- IARI, New Delhi (2017-18 and 2018-19) in split-plot design to compute the yields, economic, water and energy use-efficiency. There were 3-tillage treatment in main-plots and 4-nutrient management options in sub-plots with 3-replications. Results of present study showed that the grain yield of maize was 21.1% higher in CA-based permanent bed (PB) than conventional till (CT) plots. Net returns and net benefit cost ratio in PB plots was higher by 46.1 and 55.4% compared to CT, respectively (2-year mean basis). Two year mean basis water use-efficiency (WUE), net energy output and energy use-efficiency (EUE) were higher by 17.0, 26.3 and 12.5% in PB plots than CT. No significant effect of tillage was observed on N, P and K content (grains and stover). However, the total N, P and K uptake in maize grains and stover was higher by 23.6, 24.5 and 22.4% under PB than CT plots, respectively. Among nutrient management options; 2-year mean basis maize grain yield was 31.6 and 29.7% higher in Green Seeker (GS) guided-N and site specific nutrient management (SSNM) plots than farmers fertilizer practice (FFP), respectively. Net returns and BC ratio were also higher by 51.4-53.4% and 41.35-42.6% in GS guided-N and SSNM than FFP plots, respectively. WUE, net energy output and EUE were also significantly higher in GS guided-N treatment than FFP. Total N, P and K uptake were also significantly higher in GS guided-N and SSNM plots compared to FFP.

Co-benefits of nutrient management tailored to smallholder agriculture

Plant nutrition plays a central role in the global challenges to produce sufficient and nutritious food, lessen rural poverty, and reducing the environmental footprint of farming. Site-specific nutrient management (SSNM) provides field-specific solutions for smallholder farmers, potentially creating co-benefits of increased productivity and sustainability. Here we perform the first meta-analysis comparing SSNM with farmers’ fertilizer practice for maize, rice and wheat using 61 published papers across 11 countries. Relative to the farmer practice, across all crops SSNM increased grain yield by 12% and profitability by 15% with 10% less fertilizer nitrogen applied, thereby improving nitrogen use efficiency and reducing nitrogen pollution to the environment. Delivering it to millions of smallholder farmers requires use of digital decision support tools, but also policy incentives, links with financial and input supply services, and enhancing public-private partnerships.

Site-specific nutrient management under conservation agriculture-based spring wheat in Trans-Gangetic Plains of India

The experiment was conducted during 2018-19 and 2019-20 at ICAR-IARI research farm, to see the effect of crop establishment and nutrient management options on growth and yield of wheat under maize-wheat system. The experiment was laid out in split plot design with 03 replications, comprising conventional tillage without residue (CT-R), conventional tillage with 3 t/ha residue (CT+R), permanent raised bed without residue (PRB-R) and permanent raised bed with 3 t/ha residue (PRB+R) in main plot and nutrient management, viz. soil test-based(STB), Nutrient Expert® based (NE) and NE+ GreenSeekerTM based recommendations (NE+GS) in sub-plot. A significantly (P≤0.05) higher crop growth, viz. plant height, dry matter accumulation and leaf area index under PRB+R compared to other crop establishment technique. Differentyield parameters (yield, grain straw ratio and harvest index) and yield attributes of wheat grown under PRB+R were significantly higher (P≤0.05) over other crop establishment technique. A significantly (P≤0.05) higher crop growth, yield attributes, grain yield (5.01 and 5.05 t/ha), grain: straw ratio (0.65 and 0.65) and harvest index (39.31 and 39.36) of wheat were recorded with NE+GS based fertilization during 2018-19 and 2019- 20, respectively. Pearson correlation matrix analyzed for different growth and yield parameters showed a significant positive correlation (r) among themselves. Study infer that growing of wheat on the permanent raised bed along with 03 t/ha residue retention on surface and precision nutrient prescription using NE and GreenSeekerTM optical sensor showed promise for sustainable high productivity in intensively cultivated Trans-Gangetic Plains.

Estimating the maize biomass by crop height and narrowband vegetation indices derived from UAV-based hyperspectral images

Monitoring the aboveground biomass (AGB) of maize is essential for improving site-specific nutrient management and predicting yield to ensure food safety. A low-altitude unmanned aerial vehicle (UAV) was employed to acquire hyperspectral imagery of the maize canopy at three growth stages (V6, R1, R3) to estimate the maize AGB. Five maize nitrogen (N) rate experiments were conducted in Lishu County, Jilin Province, Northeastern China, to create different biomass conditions. Combined with crop height data obtained from the field measurements, 30 narrowband vegetation indices (VIs) were extracted using surface reflectance data from the hyperspectral imagery. Stepwise regression, random forest (RF) regression and XGBoost regression models were used to predict the fresh and dry AGB of the 2019 growth season. The study revealed that (1) crop height explained the most variability (60–70%) in the maize dry and fresh AGB estimation of the V6 growth stage, while different VIs exhibited various importance for AGB estimation at other maize growth stages; (2) XGBoost regression models demonstrated high prediction accuracy in both fresh and dry AGB estimation, compared with stepwise regression and RF models. (3) XGBoost models also presented high prediction accuracy at each single-growth stage and the whole-growth stage, with the highest accuracy for the dry AGB at V6 growth stage (R2 = 0.81, RMSE = 0.27 t/ha). This study demonstrated the capability of UAV-based hyperspectral imagery for estimating maize AGB at the field scale, which can be used to assist precision agriculture.

Assessment of Nutrient Expert ®--Hybrid Maize Model on Productivity and Profitability of Winter Maize in Terai Region of Eastern Nepal

Inadequate, unscientific, and lack of optimum utilization of fertilizer management devoid of site-specific nutrient management have been the major constraints of maize ( Zea mays L.) production in Nepal. Therefore, a multi-locational farmers’ field experiment entitled “assessing productivity and profitability of hybrid maize using Nutrient Expert ® - Hybrid Maize model and farmer’s fertilizer was planned and executed at two VDCs of Morang district in the Terai region of Nepal from December 2015 to May 2016. Nutrient Expert (NE) and Farmer’s Fertilizer Practices (FFP) treatments were imposed in a randomized complete block design (RCBD) with twenty replications. The research explored highly significant results in terms of plant number m-2, cob numbers m-, cob length, kernel rows cob-1, kernels kernel row-1, test weight, grain, stover, and biological yields and harvest index. Among the two treatments tested NE showed the highest yield (8.06 tons ha-1) than FFP (4.52 tons ha-1). While comparing net revenue, NE-based fertilizer recommendation gave the significantly higher (NRs.151.116 thousand ha-1 equivalent to $1281 ha-1) result than FFP (NRs.84.834 thousand ha-1 equivalents to $707) suggesting the adoption of NE practices to minimize the yield gaps and increasing the productivity of maize in Morang and adjoining agro-climatic conditions of eastern Terai, Nepal.

The effect of fertilization and variety on maize productivity in two tillage systems in North Sumatra

Maize is the second crucial food crop commodity that has great potential to develop in North Sumatra. The study’s objective is to determine maize production is influenced by fertilization and varieties under two tillage systems. The experiment is conducted in Batu Mamak Village, Juhar Sub-District, Karo District period March-August 2019. The three factorial experiments are tillage systems (non-tillage and conventional), fertilization (soil test kid (STK), site-specific nutrient management (PuJS), and farmers practice (FFP), and variety (Bima 2, Bima 20, JH-27, Nasa-29, NK-22, P23). Each treatment is replicated four times using a randomized complete block design with a plot size is 25 m2. The result showed that a non-tillage system with the PuJS increased grain yield by 1.1% and 21.3% compared to PuJS and FFP on the tillage system, respectively. The existing variety was still dominant compared to the newly introduced types supported by total dry matter, harvest index, and 100 grains. Bulk density was inversely related to all components was inversely associated with Ksat (infiltration). The application of organic fertilizers with a non-tillage system can increase Ksat and grain yield and provide benefits to farmers of IDR22,778,591 with a B/C ratio of 1.36.

Spatial Variability and Geostatistical Analysis of Soil Properties in the Diversified Cropping Regions of Bangladesh Using Geographic Information System Techniques

Mapping of soil properties is an important operation as it plays an important role in the knowledge about soil properties and how it can be used sustainably. The study was carried out in a local government area in Bangladesh in order to map out some soil properties and assess their variability within the area. From the study area, a total of 92 soil samples (0–20 cm) were collected from different cropping patterns at an interval of 2.2 × 2.2 km2 on a regular grid design. A portable global positioning system (GPS) was used to collect coordinates of each sampling site. Then, soil properties, that is, pH, electrical conductivity (EC), soil organic carbon (SOC), total nitrogen (Total N), and soil available nutrients (P, K, and S) were measured in the laboratory. After the normalization of data, classical statistics were used to describe the soil properties, and geostatistical analysis was used to illustrate the spatial variability of the soil properties by using kriging interpolation techniques in a GIS environment. Results show that the spatial distribution and spatial dependency level of soil properties can be different even within the small or large scale. According to cross-validation results, for most soil properties, the kriging interpolation method provided the least interpolation error. The generated maps of soil properties that indicate soil nutrient status over the study region could be helpful for farmers and decision-makers to enhance site-specific nutrient management. Also, these prototype maps would be helpful for future nutrient and fertilizer applications management, including a site-specific condition to not only reduce the cost of input management but also prevent any environmental hazard. It also demonstrates that the effectiveness of geostatistics and GIS techniques provided a powerful tool for this study in terms of regionalized nutrient management.

Precision farming technologies for water and nutrient management in rice: Challenges and opportunities

Enhancing the productivity of crops while reducing the environmental footprint are the major challenges especially for rice farming. Precison farming helps in optimising inputs such as fertilizers and water in tune with crop requirement recognizing the spatial and temporal variabilities within and across field. The precision tools viz. Remote sensing, site specific nutrient management systems, global positioning system (GPS), geographical information system (GIS), variable rate applicator, models and decision support system are used for implementing precision rice farming. The precision nutrient management technology like site specific nutrient management options, using sensors for estimating nutrient content in soil and crop and estimating the spatial variability of nutrients and mapping for variable rate fertiliser application helps in achieving the higher nutrient use efficiency compared to conventional practices. Similarly the precision water management such as sensors for moisture content determination and irrigation scheduling increases the water use efficiency. This paper covers the progress made in PF technologies for nutrient and water management focussing on challenged and opportunities in adoption of these technologies.