Timing Of Fertilizer Application Research Articles

Crop-specific management history of phosphorus fertilizer input (CMH-P) in the croplands of the United States: reconciliation of top-down and bottom-up data sources

Abstract. Understanding and assessing the spatiotemporal patterns in crop-specific phosphorus (P) fertilizer management are crucial for enhancing crop yield and mitigating environmental problems. The existing P fertilizer dataset, derived from sales data, depicts an average application rate over total cropland at the county level but overlooks cross-crop variations. Conversely, the survey-based dataset offers crop-specific application details at the state level yet lacks inter-state variability. By reconciling these two datasets, we developed long-term gridded maps to characterize crop-specific P fertilizer application rates, timing, and methods across the contiguous US at a resolution of 4 km × 4 km from 1850 to 2022. We found that P fertilizer application rate over fertilized areas in the US increased from 0.9 g P m−2 yr−1 in 1940 to 1.9 g P m−2 yr−1 in 2022, with substantial variations among crops. However, approximately 40 % of cropland nationwide has remained unfertilized in the recent decade. The hotspots for P fertilizer use have shifted from the southeastern and eastern US to the Midwest and the Great Plains over the past century, reflecting changes in cropland area, crop choices, and P fertilizer use across different crops. Pre-planting (fall and spring) and broadcast application are prevalent among corn, soybean, and cotton in the Midwest and the Southeast, indicating a high P loss risk in these regions. In contrast, wheat and barley in the Great Plains receive the most intensive P fertilization at planting and via non-broadcast application. The P fertilizer management dataset developed in this study can advance our comprehension of agricultural P budgets and facilitate the refinement of best P fertilizer management practices to optimize crop yield and to reduce P loss. Datasets are available at https://doi.org/10.5281/zenodo.10700821 (Cao et al., 2024).

Estimating soil mineral nitrogen from data-sparse field experiments using crop model-guided deep learning approach

Sandy soils are susceptible to excessive nitrogen (N) leaching under intensive crop production which is linked with the soil’s low nutrient holding capacity and high-water infiltration rate. Estimating soil mineral nitrogen (SMN) at the daily time-step is crucial in providing fertilizer recommendations balancing plant nitrogen use efficiency (NUE) and N losses to the environment. Crop models [e.g., Decision Support System for Agrotechnology Transfer (DSSAT)] can simulate SMN trend under varied fertilizer application rates and timings but struggle with accuracy in high-water table conditioned sub-irrigated soil. Alternatively, time-series deep learning (DL) models based on a long short-term memory (LSTM) are promising in understanding nonlinearity among complex variables. Yet, purely data-driven DL models for crops are challenging to develop due to limited field data availability and the excessive costs to collect more field data. Hence, a hybrid model (hybrid-LSTM) was developed by leveraging both the DSSAT and LSTM models to estimate daily SMN primarily using daily weather, applied fertilizer rates-timings, and the SMN sparse observations. This study used the observations from field trials conducted between 2011–2014 in Hastings, FL. The first step was to calibrate the DSSAT-SUBSTOR-Potato model to produce reliable SMN of the topsoil for treatments with varied N applied fertilizer rates split among the pre-planting, emergence, and tuber-initiation stages of the potato. Thereafter, the hybrid-LSTM model was trained on the calibrated DSSAT simulated SMN time-series and fine-tuned its predictions using the observed SMN to improve DSSAT simulated SMN. The hybrid-LSTM model was then tested on both calibrated and uncalibrated DSSAT SMN simulations where it outperformed the DSSAT model (improvement ranged ∼18–30 % on comparing the normalized root mean squared error) in providing reliable estimates of SMN across most of the farms and years. This novel hybrid modeling approach could guide stakeholders and farmers to build sustainable N management with improved crop NUE and yield and help in minimizing environmental losses.

Deficiency of Iron in Eucalyptus Plantations of Variable Age in Punjab and its Amelioration

The experiment was conducted during March, 2018 to March, 2020 at Research Farm of Punjab Agricultural University, Ludhiana and a few villages in Ludhiana district of Punjab, India to standardize the application of iron (Fe) in eucalyptus plantations varying from one to five years of age to eradicate Fe deficiency in these plantations. The treatments (g plant-1) consisted of plants without Fe application, 100 g S+100 g FeSO4.7H2O, 200 g S+200 g FeSO4.7H2O, 300 g S+300 g FeSO4.7H2O, 50 g Fe EDTA (iron chelate), 100 g Fe EDTA, 200 g Fe EDTA, 300 g Fe EDTA and 400 g Fe EDTA. The diameter at breast height (DBH) and height of plants were measured at the time of fertilizer application and one year after application. The DBH and height one year after application improved over increase in control by 6.86 and 7.13% respectively in first year plants with 50 g plant-1, 8.58 and 10.16% respectively in second year plants and 9.41 and 10.2% respectively in third year plants with 100 g plant-1, and 10.85 and 11.21% respectively in fourth year plants and 10.27 and 11.87% respectively in fifth year plants with 200 g plant-1 Fe EDTA alongwith correction of Fe deficiency completely. Therefore, the deficiency of Fe can be corrected by application of 50 g plant-1 Fe EDTA to first year plantations, 100 g plant-1 Fe EDTA to second and third year plantations and 200 g plant-1 Fe EDTA to fourth and fifth year plantations of eucalyptus.

Efficacy of fertilizer nitrogen source, stabilizer, and application timing for corn nitrogen nutrition

AbstractEnhancing fertilizer nitrogen use efficiency (NUE) in corn (Zea mays L.) production is critical for closing yield gaps, increasing producer profitability, and promoting environmental stewardship. In 2014 and 2015, a field experiment was conducted to determine the potential for fertilizer N stabilizer products to improve NUE of granular urea and urea ammonium nitrate (UAN) solution applied to strip‐till corn. A urease inhibitor (UI) or nitrification inhibitor (NI) or both were added at labeled rates to urea or UAN solution for a target rate of 180 kg N ha−1. At V3, a single application of broadcast granular urea and subsurface banded UAN solution with and without fertilizer N stabilizers was made. A split application (50% at V3; 50% at V6) of subsurface banded UAN solution served as a control representing a standard grower practice. Fertilizer N stabilizers improved components of NUE, such as grain N recovery efficiency (GNRE) and partial factor productivity (PFP). A single full rate UAN application did not differ in terms of grain yield each year but did result in less PFP and GNRE in 2015 as compared to the grower standard practice. A timely one‐time full season N rate subsurface banded application of UAN treated with UI and NI to improve NUE could be a viable substitute for the practice of multiple fertilizations. Untreated broadcast urea was inferior to UAN as a N source for corn, but when treated with both a UI and NI, NUE was improved.

Summer scour syndrome in weaned dairy calves: case series

BackgroundSummer scour syndrome (SSS) is a recently identified pathological condition affecting weaned dairy and dairy-beef calves during their first grazing season in Ireland. The syndrome is characterised by diarrhoea, weight loss, weakness, and can ultimately lead to death in some calves. Oral and oesophageal ulcerations are present in some cases. This study aimed to characterise a series of SSS cases in weaned dairy-bred calves on Irish commercial farms.ResultsFive farms with calves having unexplained diarrhoea at grass were referred by private veterinary practitioners (PVP) following preliminary testing to exclude coccidiosis and parasitic gastroenteritis. Farms were visited within 2 to 5 days following PVP’s referrals, or 2 days to 3 weeks relative to the onset of clinical signs. Farm management data, grass and concentrate samples, and biological samples from 46 calves (8 to 10 calves/farm) displaying clinical signs were collected. Two farms were subsequently found positive for coccidiosis and/or had chronic pneumonia problems after a thorough herd investigation and were designated as non-case farms (NCF). The remaining three farms were deemed typical SSS outbreaks (case farms; CF). Mean rumen fluid pH per farm ranged from 6.67 to 7.09 on CF, and 6.43–6.88 on NCF. Mean rumen fluid ammonia concentrations ranged from 17.6 to 29.6 mg/L and 17.2–45.0 mg/L on CF and NCF, respectively. Corresponding blood ammonia concentrations ranged from 129 to 223 µmol/L and 22–25 µmol/L. Mean blood copper and molybdenum concentrations were within normal range on all farms. Grass crude protein concentrations on the paddocks where the calves had grazed, and were currently grazing on the day of visit ranged from 137 to 148 g/kg DM and 106–177 g/kg DM, respectively on CF, and 160–200 g/kg DM and 151–186 g/kg DM, respectively on NCF. On CF, inorganic nitrogen fertiliser was applied 1 to 3 weeks pre-grazing, whereas on the two NCF, inorganic nitrogen fertiliser was applied 2 to 3 weeks pre-grazing on one farm and no fertiliser was applied on the other.ConclusionThese findings suggest that copper or molybdenum toxicity, and ruminal acidosis are not the primary causes of SSS. High blood ammonia concentrations and the timing and level of inorganic nitrogen fertiliser application to paddocks pre-grazing, warrant further investigation.

Growth of Bt cotton as influenced by time of fertilizer application and farm yard manure levels under rainfed condition

Growth of Bt cotton as influenced by time of fertilizer application and farm yard manure levels under rainfed condition

Efektivitas Pupuk Organik Cair Jerami Padi dan Ampas Teh Terhadap Pertumbuhan dan Kandungan Kalsium Tanaman Selada (Lactuca sativa L.)

This research aims to determine differences in growth and calcium levels of lettuce plants ( Lactuca sativa L.) after applying liquid organic fertilizer from rice straw and tea dregs. This research used an experimental method with a Completely Randomized Design (CRD) with 3 replications and two factors, namely the dose of liquid organic fertilizer (P1 = 10 ml and P2 = 13 ml) and the time of application of liquid organic fertilizer (W1 = once every 5 days and W2 = every 7 days). The results of the research showed that all treatments had different effects on the growth and levels of lettuce plants. The treatment that has the most influence on the growth and calcium levels of lettuce plants is P2W2 (13 ml fertilizer dose and application time every 7 days). Keywords: Tea dregs, rice straw, calcium, lettuce plants, liquid organic fertilizer

Produksi Dan Kualitas Melon (Cucumis melo L.) Pada Konsentrasi Dan Waktu Pemberian Pupuk Mono Kalium Phospate (MKP)

Potassium is really needed by melon plants to increase the sweet taste of the fruit. The element potassium can improve the size and quality of fruit during the plant's generative period and can add a sweet taste to the fruit. Meanwhile, phosphorus functions in the process of forming plant flowers and fruit as well as increasing fruit production and ripening. The aims of the research were to study interaction between the concentration and time application of MKP fertilizer on the production and quality of melon (Cucumis melo L.) and the effect of concentration and time application of MKP fertilization on the production and quality of melon (Cucumis melo L.). This experiment used Randomized Complete Block Design, which consist 2 factors, first factor was concentration of MKP fertilizer. Second factor was time application of MKP fertilizer. Data obtained were analyzed with F test, and were continued with HSD at 5 percent when significant. Results showed that there is an interaction between the concentration of MKP fertilizer and the time of application of MKP fertilizer for melon production and quality on the parameters of fruit weight, fruit diameter and total soluble solids. Providing MKP fertilizer with a concentration of 9 g.l-1 and application time of MKP fertilizer 42 and 49 days after planting is a good combination for melon production and quality in the parameters of fruit weight (3.16 kg), fruit diameter (13.65 cm), and total dissolved solids (13.73 °brix). Providing MKP fertilizer with a concentration of 9 g.l-1 is the best fertilizer concentration for melon production and quality in the parameters of fruit weight (3.16 kg), fruit diameter (13.65 cm), and total soluble solids (13.73 °brix). MKP fertilizer application time of 42 and 49 HST is the best time for melon production and quality in the parameters of fruit weight (3.16 kg), fruit diameter (13.65 cm), and total soluble solids (13.73 °brix).

Rate and time of nitrogen fertilizer application for winter camelina

AbstractWinter camelina [Camelina sativa (L.) Crantz] is a potential third crop to diversify maize (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotations in the upper Midwest. Although generally considered a low‐input crop, empirical evidence suggests that it responds to added nitrogen (N) fertilization. However, optimum agronomic N rates have not been extensively studied in the region. A study was conducted from fall 2018 to fall 2020 at three locations to assess the effects of N fertilizer application time (all N‐rate applied in spring and N‐rate split applied in fall and spring) and rates on biomass and seed yield, and quality of winter camelina. Nitrogen application time did not affect yields. Both biomass and seed yields were greatly affected by N rates at all locations. Nitrogen had minimal effects on the oil and protein content of seeds, although greater N rates were associated with a slight decrease in oil content and a slight increase in protein content. The number of branches and silicles per plant varied significantly with N rates in all locations. The seed‐to‐silicle ratio showed significant differences in two out of three locations. Residual soil N increased with increasing N rates. A fertilization rate of 67 kg ha−1 provided the highest camelina seed yield. While this study has determined the agronomic maximum rate for applied N, further economic analysis could provide comprehensive decision‐making for farmers.

A Study on the Impacts of Fertilizer Crisis on Paddy Cultivation in Five Selected Divisional Secretariat Divisions of Trincomalee District During Maha 2021/22

Rice is one of the most important cereal crops in the world. With population growth, farmers have to increase paddy production to meet existing as well as future demand. Fertilizer is the major input in rice production. Growth and yield traits of rice are affected by improper and imbalanced application of plant nutrients. Hence, suitable practices of adequate rate and timing of fertilizer application are needed to increase the rice yield. In May 2021, Imports & Exports (Control) Regulation No 07 of 2021 was issued, banning the importation of chemical fertilizers, pesticides, & herbicides in Sri Lanka. Low fertility of paddy soil created the need for adequate and constant supply of chemical fertilizers in paddy cultivation, which is a major threat to production and endangers the national food security and economy of Sri Lanka, especially in the major cropping season of Maha 2021/22. Therefore, a questionnaire survey was conducted to investigate the impact of the fertilizer crisis in major paddy-cultivating Divisional Secretariat divisions of the Trincomalee district. The random sampling method was used to select respondents for the survey, and the collected data were statistically analyzed by SPSS version 26.0 software. The results revealed that the majority of the farmers experienced a 50% yield reduction compared to the last cropping season of Maha 2020/21 in the entire five DS divisions. The seedling stage was highly affected during the fertilizer crisis in paddy cultivation in all five DS divisions. Further, the cost of production in paddy cultivation increased by more than 50% during the fertilizer crisis compared to the cost involved in Maha 2020/21. The potential for organic manure production is very poor, while the majority of farmers are interested in adopting the sustainable farming system of the Integrated Plant Nutrient System through the judicious application of chemical and organic fertilizers received on a subsidy basis, according to the present government’s fertilizer policy, which emphasizes 70% of inorganic fertilizers and 30% of organic manure application to improve sustainability in paddy cultivation in the country.

Recycled Iron Phosphates: A New Phosphorus Fertilizer for Paddy Rice.

The potential of recycled iron phosphates (FePs), e.g., vivianites (Fe3(PO4)2·8H2O) and Fe(III)-rich phosphorus (P) adsorbent materials, as phosphorus fertilizer is limited by the strong interaction between Fe and P. In this study, the efficiency of FePs as P fertilizer was explored by applying them as granules or powder in flooded strongly P-fixing soils (acid and calcareous), thereby taking advantage of increased P release induced by reductive dissolution of P-bearing Fe(III) minerals. First, no P diffusion from granular FeP fertilizers into flooded soils was detectable by the diffusive gradient in thin films (DGT) technique and microfocused X-ray fluorescence (μ-XRF) analysis of thin soil sections, in contrast to detectable P diffusion away from granules of soluble triple superphosphate (TSP) fertilizer. On the contrary, powdered FePs demonstrated an excellent increase in extractable P (1 mM CaCl2) in a 120-day incubation experiment in flooded soils. Second, a pot experiment was performed with rice (Oryza sativa) grown in flooded acid and calcareous soils. The fertilizer value of FePs was remarkable when dosed as powder, as it was even up to 3-fold higher than TSP in the acid soil and similar to TSP in the calcareous soil. The beneficial effect of FeP over TSP in the acid soil is attributed to the slow release of P from FePs, which allows to partly overcome P fixation. The promising results of FePs as P fertilizer applied as powders in flooded soils debunk the generally accepted idea that FePs are poor sources of P while demonstrating the importance of the timing of FeP fertilizer application.

Corn 15N uptake and partitioning in response to fertilizer application rate and timing

AbstractNitrogen (N) fertilizer applications near the time of planting are important for upper US Midwest corn (Zea mays L.) production, but wet springs may result in significant N losses. Split applications may circumvent this problem and improve fertilizer uptake and use efficiency, but the relative contribution of N from the soil and fertilizer is poorly understood. A field study with six sites in Minnesota received 15N‐labeled urea fertilizer in the first year and unlabeled urea in the second year to determine the effect of N rate and application timing on corn uptake and accumulation patterns of fertilizer‐derived N (FDN) and soil‐derived N (SDN) over two consecutive growing seasons. Corn responded positively to fertilization. The percentage of total N uptake as FDN was greatest closest to the time of application but decreased over time as SDN became the dominant N source. A split application (45 kg N ha−1 at planting, 90 kg N ha−1 at V4) significantly improved FDN uptake over the 135 kg N ha−1 preplant treatment but did not improve total N uptake in the first year at any site. Fertilizer‐N use efficiency (F15NUE) using the isotopic method was 2.8%–43.3% across all sites at the end of the first year with the majority partitioned to the grain. At the end of the second year, approximately 2.2% of the first‐year applied FDN was recovered in aboveground biomass. Fertilization ensures adequate N availability to the developing crop, but ultimately SDN contributed ≥61% of the total N uptake.

Effect of type and time of fertilizer application in foliar fertilization on production and seed quality of cayenne (Capsicum frutescens L. var. Bonita)

Cayenne (Capsicum frutescens L.) classified as a horticultural crop that has high economic value. The use of fertilizer can affect the maximum growth and production of cayenne plants, so it is necessary to know the right type and time. The purpose of the study was to find the best type and time of fertilizer application for the production and quality of cayenne seeds. This study used a randomized block design with two treatment factors, the first factor was the type of fertilizer, namely Gandasil B fertilizer, Bayfolan, White KNO3 and NPK Mutiara, the second factor was the time of fertilizer application, namely fertilizer application during flowering, as well as during flowering and fruit enlargement. The results showed that the interaction between the type and time of fertilizer application had a very significant effect on the total sugar content of leaves. Fertilizer treatment has a very significant effect on the total sugar content of leaves, has a significant effect on the number of fruits per plant, weight per fruit, growth uniformity, percentage of normal and abnormal sprouts, and germination. The best type of fertilizer for fruit production is Bayfolan while judging from seed quality, the best type of fertilizer for seed production is NPK Mutiara. The timing of fertilizer application had a very significant effect on the total sugar content of the leaves but had no significant effect on other variables. The best application time for seed production is fertilizer application during flowering plants and fruit enlargement.

Integrated Soil Applied Fertilizers (Nitrogen, Zinc, and Boron) Effects on Growth and Yield of Sunflower

In the case of sunflower production, precision agriculture can be used to determine the optimal fertilizer application rates and timings based on the specific soil and climatic conditions of a particular field. The response of sunflower to macro- and micronutrient applications has been observed. Field conditions were used to assess the effectiveness of applying nitrogen, zinc, and boron alone or in a mixture to improve the growth and production of sunflower HO-1. The experiment followed an RCBD design with a net plot size of 4x5 (20 m2). The study examined the impact of different applied soil fertilizers, including NPK. The suggested doses of T1 (control) and T2 (soil) of applied fertilizer Nitrogen 1000g ha-1, T3 soil applied fertilizer Zinc 1000g ha-1, T4 soil applied fertilizer Boron 1000g ha-1, T5 soil applied fertilizers Nitrogen 1000g ha-1 + Zinc 1000g ha-1; T6 Nitrogen 1000g ha-1 + Boron 1000g ha-1; T7 soil applied fertilizers Zinc 1000g ha-1 + Boron 1000g ha-1, T8 soil applied fertilizers Nitrogen 1000g ha-1 and boron 1000g ha-1, T8 were examined. The result indicated that the application of soil-applied fertilizers Nitrogen 1000g ha-1 zinc 1000g ha-1 and boron 1000g ha-1 in combination, yielded the most significant improvements in Maximum plant height: 181.0 cm; number of leaves per plant: 36.80; stem girth: 12.35; head diameter: 26.30; number of seeds: 652.0; seed weight: 40.74; seed index: 62.66; and seed yield (kg-1): 2230.

Nitrogen fertilizer source, rate, placement, and application timing effect on sorghum (grain and forage) and corn grain yields

AbstractIdentifying the limiting nutrient, fertilizer source, rate, placement, additives, and timing of application are critical components of fertilizer management. The objective of this study was to quantify the impact of nitrogen (N) fertilizer source, rate, placement method, additives, application timing, and environment on yields of grain sorghum, forage sorghum [Sorghum bicolor (L.) Moench], and corn (for grain, Zea mays L.). Independent field experiments were conducted at 13 different environments in Kansas from 2008 through 2013 on grain sorghum, forage sorghum, and corn. Treatments were an incomplete factorial combination of four fertilizer placement methods, three fertilizer types, five fertilizer additives, three fertilizer application times, and six fertilizer rates that varied by location and across years. Results showed grain and forage sorghum yields responded to N fertilizer in environments that were not extremely dry (<136 mm) or wet (>651 mm). Corn responded to N fertilizer application only in high‐precipitation environments. For grain sorghum, where rate × placement × source × additive interaction was significant, broadcast application of urea (source) at high rates (67–134 kg N ha−1), with summer application timing, or with additive in winter (with environmentally smart nitrogen [ESN]) resulted in up to 43% greater yield compared with application of urea‐ammonium nitrate (UAN; source) and surface band (placement) at 67 kg ha−1 without additives. In the one site‐year where forage sorghum responded to fertilizer application, forage yields with preplant application of UAN at 56–140 kg ha−1 were 164% greater than the control. For corn, application of either urea or UAN fertilizer, UAN in coulter or surface band, with ESN blend, applied at planting, and at highest rates (160 kg ha−1) resulted in best yields compared with the alternatives and 110% greater yield compared with the unfertilized control. We concluded that fertilizer rate is an important management component as it consistently affected yield regardless of crop considered. Fertilizer placement and timing have crop‐specific importance as they were significant for only corn, but the main effect of additives (N stabilizers) was not significant for any of the crops. Environment and crop type influenced crop response to N fertilizer rate, timing, placement, and additives.

Evaluating responses by ChatGPT to farmers’ questions on irrigated lowland rice cultivation in Nigeria

The limited number of agricultural extension agents (EAs) in sub-Saharan Africa limits farmers’ access to extension services. Artificial intelligence (AI) assistants could potentially aid in providing answers to farmers’ questions. The objective of this study was to evaluate the ability of an AI chatbot assistant (ChatGPT) to provide quality responses to farmers’ questions. We compiled a list of 32 questions related to irrigated rice cultivation from farmers in Kano State, Nigeria. Six EAs from the state were randomly selected to answer these questions. Their answers, along with those of ChatGPT, were assessed by four evaluators in terms of quality and local relevancy. Overall, chatbot responses were rated significantly higher quality than EAs’ responses. Chatbot responses received the best score nearly six times as often as the EAs’ (40% vs. 7%). The evaluators preferred chatbot responses to EAs in 78% of cases. The topics for which the chatbot responses received poorer scores than those by EAs included planting time, seed rate, and fertilizer application rate and timing. In conclusion, while the chatbot could offer an alternative source for providing agricultural advisory services to farmers, incorporating site-specific input rate-and-timing agronomic practices into AI assistants is critical for their direct use by farmers.

A global meta-analysis of yield-scaled N2 O emissions and its mitigation efforts for maize, wheat, and rice.

Maintaining or even increasing crop yields while reducing nitrous oxide (N2 O) emissions is necessary to reconcile food security and climate change, while the metric of yield-scaled N2 O emission (i.e., N2 O emissions per unit of crop yield) is at present poorly understood. Here we conducted a global meta-analysis with more than 6000 observations to explore the variation patterns and controlling factors of yield-scaled N2 O emissions for maize, wheat and rice and associated potential mitigation options. Our results showed that the average yield-scaled N2 O emissions across all available data followed the order wheat (322 g N Mg-1 , with the 95% confidence interval [CI]: 301-346) > maize (211 g N Mg-1 , CI: 198-225) > rice (153 g N Mg-1 , CI: 144-163). Yield-scaled N2 O emissions for individual crops were generally higher in tropical or subtropical zones than in temperate zones, and also showed a trend towards lower intensities from low to high latitudes. This global variation was better explained by climatic and edaphic factors than by N fertilizer management, while their combined effect predicted more than 70% of the variance. Furthermore, our analysis showed a significant decrease in yield-scaled N2 O emissions with increasing N use efficiency or in N2 O emissions for production systems with cereal yields >10 Mg ha-1 (maize), 6.6 Mg ha-1 (wheat) or 6.8 Mg ha-1 (rice), respectively. This highlights that N use efficiency indicators can be used as valuable proxies for reconciling trade-offs between crop production and N2 O mitigation. For all three major staple crops, reducing N fertilization by up to 30%, optimizing the timing and placement of fertilizer application or using enhanced-efficiency N fertilizers significantly reduced yield-scaled N2 O emissions at similar or even higher cereal yields. Our data-driven assessment provides some key guidance for developing effective and targeted mitigation and adaptation strategies for the sustainable intensification of cereal production.

Desenvolvimento e produtividade de gergelim (cultivar k3) em latossolo amarelo em função da adubação potássica

ABSTRACT Sesame (Sesamum indicum L.) is an oilseed crop species valued for its nutritional properties. Sesame production has been a strategic alternative for expanding agricultural diversification in Mato Grosso, Brazil. In this context, the objective of this study was to assess growth and seed yield of sesame plants (cultivar K3) grown in a Typic Hapludox soil under potassium (K) fertilizer application. The experiment was conducted in a randomized block design with four replications, using a 6×4 factorial arrangement consisting of six K2O rates (0, 30, 50, 70, 90, and 120 kg ha-1) and four application times (0, 20, 30, and 40 days after sowing). Agronomic parameters were evaluated, including plant height, first capsule height, numbers of branches and capsules per plant, capsule weight, 1000-seed weight, and seed yield. Soil samples were chemically analyzed after harvest. Individual factors (K2O rates and application times) and the interaction between factors had no significant effects on plant height, first capsule height, number of branches per plant, and capsule and 1000-seed weights. The timing of fertilizer application did not significantly affect plant growth and seed yield. However, K fertilizer application increased soil K contents, number of capsules per plant, and seed yield. The highest seed yield was found for the K2O rate of 90 kg ha-1.

ЕКСПРЕС-ДІАГНОСТИКА ХЛОРОФІЛУ НА ПОСІВАХ ПШЕНИЦІ ОЗИМОЇ

The purpose of this research is a comparative analysis of the chlorophyll content in two varieties of winter wheat in different periods of plant development using an autonomous field device (N-tester) for operational measurement of nitrogen content and calculation of the optimal dose of nutrient application on winter wheat crops during different phases of vegetation. Methods and materials. The research was conducted in the Oleksandrivskyi and Bobrynetskyi districts of Kirovohrad region on the fields of two farms on winter wheat crops (varieties «Memory» and «Avenue») with selected control plots with an area of 3 m2 each. At the key moments of plant development, before applying fertilizers, chlorophyll was measured using the N-tester «CSM-200 Plus GPS» and the sugar content was measured with a refractometer «HT116ATC», after which the required dose of application of drugs was calculated. In both farms, fertilizing was carried out at the optimal time of fertilizer application, but the rates of fertilizer were radically different. Results. Wheat of the «Memory» variety in the control plot (the total amount of applied nitrogen was 198 kg/ha), starting from the earing phase, looked greener, taller, the ear had a larger size, the indicators of the N-tester and the content of sugars in the control plot had higher indicators, but also the ripening period in the control plot lasted longer than in the rest of the field (the total amount of applied nitrogen per year was 101 kg/ha). Winter wheat of the «Avenue» variety in terms of the main indicators in the control plot (the total amount of applied nitrogen 145 kg/ha) and in the field (the total amount of applied nitrogen 183 kg/ha) almost did not differ: the length of the ear, the height of the plant, and the color are the same, the indicators of the N-tester and the content of sugars are also almost the same. Therefore, it can be concluded that the introduction of an additional amount of 38 kg/ha per year was ineffective and did not increase productivity. Conclusions. Operational measurement of the nitrogen content in field conditions using the N-tester made it possible to effectively calculate the doses of nutrients applied to winter wheat crops during different phases of vegetation and contributed to increasing the yield level of the investigated crop varieties. Keywords: fertilizers, plant nutrition, winter wheat, refractometer, harvest, phases of plant development, chlorophyll, N-tester.

Annual Urea Nitrogen Contribution to the Nutrition of Cabernet Sauvignon Grapevine Grown in Sandy and Clayey Soil

The timing of nitrogen fertilizer application in vineyards can determine the amount of nitrogen (N) absorbed, distributed, and accumulated in grapevine organs. The study aimed to evaluate the annual contribution of N from urea, applied at different times in Cabernet Sauvignon, grown in sandy and clayey soil in a subtropical climate. The sandy soil received 21.42 kg N ha−1 and the clayey soil 30 kg N ha−1, both enriched with 3% excess 15N atoms, applied at different times. The N derived from the fertilizer in grapevines, at all times of N application, and in sandy and clayey soil did not exceed 8%, with the highest values being observed in annual organs, especially in the leaves. The application of N marked at the phenological stages of IBB (50% at beginning of budbreak + 50% at full budbreak) enabled greater absorption of N derived from the fertilizer by the vines grown in both sandy and loamy soil. The N present in the annual organs (leaves, berries, stalks, and shoots) and in the perennial organs (stems and canes) of Cabernet Sauvignon grown in sandy and clayey soil was derived in greater percentages from the soil.