Predicting N Status in Maize with Clip Sensors: Choosing Sensor, Leaf Sampling Point, and Timing

Nitrogen (N) losses from agricultural systems increase air and water pollution, and these losses are highly correlated with the excessive fertilization. An adjusted N fertilization is then a key factor in increasing the N fertilizer efficiency, and leaf clip sensors can help to improve it. This study (combining five different field experiments in Central Spain) tried to identify the ability of the clip sensors in maize N status identification and yield prediction, comparing two different devices (SPAD-502® and Dualex®) and identifying the best protocol for maize leaf sampling. As a result, the study demonstrated that different leaf clip chlorophyll sensors presented similar results, although some differences appeared at larger N concentrations. Complementary polyphenol information (as flavonol) can improve the maize N deficiency prediction. Moreover, valuable information for a proper sampling protocol was obtained with this study. It proved that the sampling position (in the leaf and in the plant) and sampling time were crucial for a better estimation of the maize N status. Proper fertilization recommendations could be achieved based on clip chlorophyll sensor measurements.

Download Full-text

Direct and Indirect Effects of Urease and Nitrification Inhibitors on N2O-N Losses from Urea Fertilization to Winter Wheat in Southern Germany

Atmosphere ◽

10.3390/atmos11080782 ◽

2020 ◽

Vol 11 (8) ◽

pp. 782 ◽

Cited By ~ 1

Author(s):

Yuncai Hu ◽

Manuela P. Gaßner ◽

Andreas Weber ◽

Martine Schraml ◽

Urs Schmidhalter

Keyword(s):

Winter Wheat ◽

Field Experiments ◽

N2o Emission ◽

N Fertilization ◽

N Fertilizer ◽

N2o Emissions ◽

Nitrification Inhibitors ◽

N Losses ◽

Calcium Ammonium Nitrate ◽

Southern Germany

Urea (U) is the most important nitrogen (N) fertilizer in agriculture worldwide, and as N fertilizer can result in large gaseous losses of NH3 and N2O. Thus, urease inhibitors (UIs) and nitrification inhibitors (NIs) have been coupled with U fertilizers to mitigate NH3 and N2O emissions. However, it is still unclear whether adding NIs and/or UIs to U stimulates other pollutants, while reducing one pollutant. Furthermore, part of the NH3 deposition to earth is converted to N2O, leading to indirect N2O emission. To estimate direct and indirect effect of UIs and NIs on the N2O-N and NH3-N losses from U; therefore, we analyzed multi-year field experiments from the same site during 2004 to 2005 and 2011 to 2013. The field experiments with U fertilization with or without UI (IPAT, N-isopropoxycarbonyl phosphoric acid triamide) and NI (DCD/TZ, Dicyandiamide/1H-1, 2, 4-Triazol) in winter wheat and with calcium ammonium nitrate (CAN) were conducted in southern Germany. Fluxes of NH3 or N2O emissions were determined following each split N fertilization in separate experiments on the same site. Our results showed that U with NIs considerably reduced N2O emissions, and adding UIs decreased NH3 emissions. However, the effect on N2O emissions exerted by (U + UIs) or (U + UIs + NIs) was inconsistent. In contrast to the treatment of (U + UIs + NIs), the addition of NIs alone to U stimulated NH3 emission compared to treatment with U. When 1% indirect N2O emission from NH3 (IPCC emission factor (EF4)) was considered to estimate the indirect N2O emission, total N2O emissions from (U + NIs) were approximately 29% compared to that from U alone and 36% compared to that from (U + UI), indicating that indirect N2O emission from NH3 induced by NIs may be negligible.

Download Full-text

Testing Proximal Optical Sensors on Quinoa Growth and Development

Remote Sensing ◽

10.3390/rs12121958 ◽

2020 ◽

Vol 12 (12) ◽

pp. 1958 ◽

Cited By ~ 2

Author(s):

Jorge Alvar-Beltrán ◽

Carolina Fabbri ◽

Leonardo Verdi ◽

Stefania Truschi ◽

Anna Dalla Marta ◽

...

Keyword(s):

Optical Sensors ◽

High Performance ◽

Statistical Significance ◽

Sowing Date ◽

N Fertilization ◽

Coefficient Of Determination ◽

N Losses ◽

Predicted Values ◽

Seed Yields ◽

N Status

Proximal optical sensors (POSs) are effective devices for monitoring the development of crops and the nitrogen (N) status of plants. POSs are both useful and necessary in facilitating the reduction of N losses into the environment and in attaining higher nitrogen use efficiency (NUE). To date, no comparison of these instruments has been made on quinoa. A field experiment conducted in Tuscany, Italy, with different POSs, has assessed the development of quinoa with respect to N status. Three sets of POSs were used (SPAD-502, GreenSeeker, and Canopeo App.) to monitor quinoa development and growth under different types of fertilizers (digestate and urea) and levels of N fertilization (100, 50, and 0 kg N ha−1). The present findings showed that in-season predictions of crop biomass at harvest by SPAD-502 and GreenSeeker optical sensors were successful in terms of the coefficient of determination (R2 = 0.68 and 0.82, respectively) and statistical significance (p < 0.05), while the Canopeo App. was suitable for monitoring the plant´s canopy expansion and senescence. The relative error (RE%) showed a remarkably high performance between observed and predicted values, 5.80% and 4.12% for GreenSeeker and SPAD-502, respectively. Overall, the POSs were effective devices for monitoring quinoa development during the growing season and for predicting dry biomass at harvest. However, abiotic stresses (e.g., heat-stress conditions at flowering) were shown to reduce POSs’ accuracy when estimating seed yields at harvest, and this problem will likely be overcome by advancing the sowing date.

Download Full-text

Environmental Impact of Rotationally Grazed Pastures at Different Management Intensities in South Africa

Animals ◽

10.3390/ani11051214 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1214

Author(s):

Hendrik P. J. Smit ◽

Thorsten Reinsch ◽

Pieter A. Swanepoel ◽

Ralf Loges ◽

Christof Kluß ◽

...

Keyword(s):

South Africa ◽

N Fertilization ◽

Yield Response ◽

N2o Emissions ◽

Pasture Management ◽

N Losses ◽

Enteric Fermentation ◽

Soil C ◽

Grazed Pastures ◽

Soil C And N

Nitrogen fertilization, irrigation and concentrate feeding are important factors in rotational pasture management for dairy farms in South Africa. The extent to which these factors affect environmental efficiency is subject to current and intense debate among scientists. A three-year field study was conducted to investigate the yield response of different N-fertilizer treatments (0 (N0), 220 (N20), 440 (N40), 660 (N60) and 880 (N80) kg N ha−1 year−1) on grazed pastures and to calculate the carbon footprint (CF) of milk produced. Excessive N-fertilization (N60 and N80) did not increase herbage dry matter and energy yields from pastures. However, N80 indicated the highest N-yield but at the same time also the highest N surpluses at field level. A maximum fertilizer rate of 220 kg ha−1 year−1 (in addition to excreted N from grazing animals) appears sufficient to ensure adequate herbage yields (~20 t DM ha−1 year−1) with a slightly positive field-N-balance. This amount will prevent the depletion of soil C and N, with low N losses to the environment, where adequate milk yields of ~17 t ECM ha−1 with a low CF (~1.3 kg CO2 kg ECM−1) are reached. Methane from enteric fermentation (~49% ± 3.3) and N2O (~16% ± 3.2) emissions from irrigated pastures were the main contributors to the CF. A further CF reduction can be achieved by improved N-fertilization planning, low emission irrigation techniques and strategies to limit N2O emissions from pasture soils in South Africa.

Download Full-text

The interaction of seasonal rainfall and nitrogen fertiliser rate on soil N2O emission, total N loss and crop yield of dryland sorghum and sunflower grown on sub-tropical Vertosols

Soil Research ◽

10.1071/sr15286 ◽

2016 ◽

Vol 54 (5) ◽

pp. 604 ◽

Cited By ~ 23

Author(s):

G. D. Schwenke ◽

B. M. Haigh

Keyword(s):

Crop Yield ◽

Crop Production ◽

Field Experiments ◽

N2o Emission ◽

N2o Emissions ◽

N Loss ◽

N Losses ◽

Total N ◽

Tropical Regions ◽

The Impact

Summer crop production on slow-draining Vertosols in a sub-tropical climate has the potential for large emissions of soil nitrous oxide (N2O) from denitrification of applied nitrogen (N) fertiliser. While it is well established that applying N fertiliser will increase N2O emissions above background levels, previous research in temperate climates has shown that increasing N fertiliser rates can increase N2O emissions linearly, exponentially or not at all. Little such data exists for summer cropping in sub-tropical regions. In four field experiments at two locations across two summers, we assessed the impact of increasing N fertiliser rate on both soil N2O emissions and crop yield of grain sorghum (Sorghum bicolor L.) or sunflower (Helianthus annuus L.) in Vertosols of sub-tropical Australia. Rates of N fertiliser, applied as urea at sowing, included a nil application, an optimum N rate and a double-optimum rate. Daily N2O fluxes ranged from –3.8 to 2734g N2O-Nha–1day–1 and cumulative N2O emissions ranged from 96 to 6659g N2O-Nha–1 during crop growth. Emissions of N2O increased with increased N fertiliser rates at all experimental sites, but the rate of N loss was five times greater in wetter-than-average seasons than in drier conditions. For two of the four experiments, periods of intense rainfall resulted in N2O emission factors (EF, percent of applied N emitted) in the range of 1.2–3.2%. In contrast, the EFs for the two drier experiments were 0.41–0.56% with no effect of N fertiliser rate. Additional 15N mini-plots aimed to determine whether N fertiliser rate affected total N lost from the soil–plant system between sowing and harvest. Total 15N unaccounted was in the range of 28–45% of applied N and was presumed to be emitted as N2O+N2. At the drier site, the ratio of N2 (estimated by difference)to N2O (measured) lost was a constant 43%, whereas the ratio declined from 29% to 12% with increased N fertiliser rate for the wetter experiment. Choosing an N fertiliser rate aimed at optimum crop production mitigates potentially high environmental (N2O) and agronomic (N2+N2O) gaseous N losses from over-application, particularly in seasons with high intensity rainfall occurring soon after fertiliser application.

Download Full-text

Evaluation of reed canary grass (Phalaris arundinacea L.) grown for energy use

Research in Agricultural Engineering ◽

10.17221/35/2011-rae ◽

2012 ◽

Vol 58 (No. 4) ◽

pp. 119-130 ◽

Cited By ~ 13

Author(s):

Z. Strašil

Keyword(s):

Energy Use ◽

Field Experiments ◽

Energy Content ◽

N Fertilization ◽

Reed Canary Grass ◽

The Czech Republic ◽

Pests And Diseases ◽

Application Rates ◽

Average Loss ◽

Canary Grass

Field experiments with reed canary grass were conducted during 1996–2000 at four different sites (Ruzyně, Troubsko, Lukavec and Chomutov in the Czech Republic). In the period 2001–2009 the experiments were run at Ruzyně and Lukavec. During vegetation the following indicators were monitored: the course of weather in individual years at given sites and infestation of stands by pests and diseases. Furthermore, we monitored the effects of N application rates, year, site, as well as the effect of harvest time on yields of harvested biomass, moisture content, elements content, and energy content. The content of heavy metals in soils and subsequently in plants was also monitored. The zoning methodology was created for reed canary grass. The highest average dry matter yield of reed canary grass harvested in late autumn was achieved for comparable periods during 1996–2000 at Ruzyně (8.33 t/ha), and the lowest at Chomutov (6.80 t/ha). The greatest effect of N fertilization on yields was recorded at Ruzyně, where the N2 rate (80 kg/ha) increased the yield on average by 28.6% in comparison with the non-fertilized variants. Average loss of biomass over winter was 23.0%.

Download Full-text

Impact of Row Spacing, Sowing Density and Nitrogen Fertilization on Yield and Quality Traits of chia (Salvia Hispanica L.) Cultivated in southwestern Germany

Agronomy ◽

10.3390/agronomy9030136 ◽

2019 ◽

Vol 9 (3) ◽

pp. 136 ◽

Cited By ~ 2

Author(s):

Samantha Grimes ◽

Timothy Phillips ◽

Filippo Capezzone ◽

Simone Graeff-Hönninger

Keyword(s):

Field Experiments ◽

Seed Mass ◽

N Fertilization ◽

Row Spacing ◽

Quality Traits ◽

Yield And Quality ◽

Chia Seed ◽

Salvia Hispanica L ◽

Growing Conditions ◽

Seed Yields

To obtain high chia seed yields and seed qualities, a suitable crop management system needs to be developed for the given growing conditions in southwestern Germany. Field experiments were conducted at the experimental station Ihinger Hof in two consecutive years (2016, 2017). The study aimed to evaluate yield and quality traits of chia depending on different (i) row spacing (35, 50 and 75 cm), (ii) sowing densities (1, 1.5 and 2 kg ha−1) and, (iii) N-fertilization rates (0, 20 and 40 kg N ha−1). It consisted of three independent, completely randomized field experiments with three replications. Results showed that chia seed yields ranged from 618.39 to 1171.33 kg ha−1 and that a thousand seed mass of 1.14 to 1.24 g could be obtained. Crude protein-, crude oil- and mucilage contents varied from 18.11–23.91%, 32.16–33.78% and 10.00–13.74%, respectively. Results indicated that the year of cultivation and the accompanied environmental conditions, like precipitation or temperature, influenced the determined traits more than the applied agronomic practices. As average seed yields exceeded those obtained in the countries of origin (Mexico, Guatemala) while having comparable quality characteristics, chia holds great potential as an alternative crop for farmers in southwestern Germany.

Download Full-text

Moderators of Perceived Effort in Adolescent Rowers During a Graded Exercise Test

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17218063 ◽

2020 ◽

Vol 17 (21) ◽

pp. 8063

Author(s):

Gerd Schmitz

Keyword(s):

Exercise Test ◽

Self Regulation ◽

Perceived Effort ◽

Beneficial Effects ◽

Graded Exercise Test ◽

Subjective Perceptions ◽

Graded Exercise ◽

Key Factor ◽

Cognitive Competencies ◽

Highly Correlated

Physical activity promotes mental health. A key factor is self-regulation. In the field of sports, self-regulation is related to the psychophysiological competence of rating of perceived effort (RPE). It was reported that adolescents have lower RPE competencies than adults, and it was hypothesized that this effect depends on physiological and cognitive development. The present study investigated in a sample of adolescents whether the RPE is related to basic cognitive competencies. Twelve rowers performed cognitive tests and a graded exercise test on a rowing ergometer, in which they continuously rated their perceived effort. Objective load measures and subjective perceptions were highly correlated (rho = 0.95–0.99). Furthermore, these correlations were inter-individually moderated by measures of mental speed and spontaneous flexibility. The results confirm the significance of basal cognitive competencies for conscious load perception. It is discussed whether regular sport has beneficial effects on the development of RPE competencies by enhancing cognitive regulation.

Download Full-text

Nitrogen Utilization in a Cereal-Legume Rotation Managed with Sustainable Agricultural Practices

Agronomy ◽

10.3390/agronomy9030113 ◽

2019 ◽

Vol 9 (3) ◽

pp. 113 ◽

Cited By ~ 3

Author(s):

Mariangela Diacono ◽

Paola Baldivieso-Freitas ◽

Francisco Sans Serra

Keyword(s):

Green Manure ◽

Crop Production ◽

Farmyard Manure ◽

Agricultural Practices ◽

Residual Effect ◽

N Fertilization ◽

Climatic Conditions ◽

N Losses ◽

Sustainable Agricultural Practices ◽

N Use

Optimization of the nitrogen (N) inputs and minimization of nutrient losses strongly affect yields in crop rotations. The aim of this research was to evaluate the effect of agricultural practices on yield and N use in a 4-year cereal-legume rotation in organic farming and to identify the best combination of these practices. The following treatments were compared: conventional plough (P) vs. reduced chisel (RC) tillage; composted farmyard manure (F) vs. unfertilized control (NF); and green manure (GM) vs. no green manure (NoM). No significant differences were found for N use efficiency between P and RC in each crop. The results suggested that legumes in the tested rotation do not need supplemental N fertilization, particularly if combining GM and F. The use of composted farmyard manure should be considered in a long-term fertilization plan for cereals, to allow a higher efficiency in N use. The residual effect of fertilization over time, along with the site-specific pedo-climatic conditions, should also be considered. In both tested tillage approaches, soil N surplus was the highest in plots combining GM and F (i.e., more than 680 kg N ha−1 in combination with RC vs. about 140 kg N ha−1 for RC without fertilization), with a risk of N losses by leaching. The N deficit in NoM–NF both combined with P and RC would indicate that these treatment combinations are not sustainable for the utilized crops in the field experiment. Therefore, the combination of the tested practices should be carefully assessed to sustain soil fertility and crop production.

Download Full-text

Growth, Critical N Concentration and Crop N Demand in Butterhead and Crisphead Lettuce Grown under Mediterranean Conditions

Agronomy ◽

10.3390/agronomy9110681 ◽

2019 ◽

Vol 9 (11) ◽

pp. 681 ◽

Cited By ~ 1

Author(s):

Conversa ◽

Elia

Keyword(s):

Field Experiments ◽

Environmental Issues ◽

Dry Weight ◽

Crop Productivity ◽

N Fertilization ◽

Use Efficiency ◽

Butterhead Lettuce ◽

N Demand ◽

N Use ◽

Critical N Concentration

Excessive nitrogen (N) fertilizers are applied in lettuce causing both environmental issues and N crop luxury consumption. In order to improve the N use efficiency (NUE) by defining optimal crop growth and N requirements of butterhead and crisphead lettuce, two field experiments were conducted using 0, 50, and 100 kg ha−1 of N fertilizer to study (i) the growth and productivity, (ii) the NUE, (iii) the critical N dilution curve, and (iv) the N demand. Nitrogen supply enhanced dry weight (DW) accumulation in the butterhead (from 295 to 410 g m−2), but not in the crisphead type (251 g m−2). The NUE indices underlined the poor ability of the crisphead type in absorbing soil N and also in the utilization of the absorbed N for producing DW. The critical N dilution curves %Nc = 3.96 DW−0.205 and %Nc = 3.65 DW−0.115 were determined for crisphead and butterhead lettuce, respectively. Based on these type-specific %Nc curves, the estimated N demand was 125 kg ha−1 in the butterhead and 80 kg ha−1 in the crisphead lettuce for producing 4.3 and 2.5 Mg ha−1 of DW, respectively, under Mediterranean climate. Neither N fertilization nor genotype affected crop productivity.

Download Full-text

Fertilization effects on the fungal biomass in grasslands

10.5194/egusphere-egu2020-16110 ◽

2020 ◽

Author(s):

Ana Barreiro ◽

Aaron Fox ◽

Andreas Lüscher ◽

Franco Widmer ◽

Linda-Maria Dimitrova Mårtersson

Keyword(s):

Nitrogen Fertilization ◽

Mycorrhizal Fungi ◽

Fungal Biomass ◽

Field Experiments ◽

Production Systems ◽

Arbuscular Mycorrhizal ◽

Fatty Acid Analysis ◽

N Fertilization ◽

Lipid Fatty Acid ◽

Neutral Lipid Fatty Acid

Fertilisation is a common practise in grass production systems performed to increase primary production, a supporting ecosystem service essential for other services. However, different fungal groups, like saprothropic fungi (SF) and the obligate symbionts arbuscular mycorrhizal fungi (AMF), have potential differential response to the fertilizer concentration and composition. Three controlled field experiments were utilised in our study, two medium-term (6 years) in the south of Sweden (SE) and one long-term experiment (46 year) in Switzerland (CH), all sampled in 2018. The Swedish sites included the same two factor treatment, i.e. four different plant mixtures and two (SE-Lanna) or three (SE-Alnarp) nitrogen fertilization levels (0, 60, 120 kg ha-1 yr-1); while the Swiss experiment&#160; included different proportions of N, P and K fertilization under different cutting regimes (CH-Bremgarten). The PLFA and NLFA (phospholipid- and neutral lipid fatty acid) analysis was used to estimate the fungal biomass (SF+AMF). The application of N was associated with a decrease in the AMF biomass, with significant effects with the application of 60 and 120 kg N ha-1 in SE-Alnarp, and 75 and 150 kg N ha-1 in CH-Bremgarten. On the other hand, the SF biomass was only negatively affected by the N fertilization in SE-Lanna (60 kg N ha-1) under the plant mixture that showed the biggest SF biomass in the unfertilized plot; and by the highest application of N in CH-Bremgarten. Our findings indicate that nitrogen fertilization influences microbial community structure and reduces the abundance of AMF, with these being more sensitive than SF to fertilizer application.

Download Full-text