Most Asked Agronomic Questions

Exact date of bulletin unknown.PDF pages: 4

Using Canopies indices to Quantify the Economic optimum nitrogen rate in Spring Wheat

In-season N applications to spring wheat (Triticum aestivum L.) may increase profits and improve N fertilizer accuracy. The objectives were to develop a calibration tool employing normalized difference vegetative index (NDVI) and SPAD 502 chlorophyll meter (SPAD) measurements for calculating the differential from the economic optimum N rate (dEONR) at growth stages Z22, Z24, and Z31 to Z39 and provide N rate algorithms for use in applying N fertilizer at a variable rate. Sensing was conducted trials over 3 yr encompassing 10 site-years across Southeastern Buenos Aires Province, Argentina. The relationship between sensor indices and dEONR was evaluated by fitting quadratic plateau (QP) regression models. Statistically significant QP models were determined at the Z24, Z31, and Z39 growth stages. Relative SPAD (rSPAD) and relative NDVI (rNDVI) reduced variation and improved the calibration of measured N stress with the dEONR. For Z31 and Z39, the rSPAD had the best goodness of fit statistics when compared to rNDVI [adjusted R2 (adjR2)= 0.67 and 0.57 at Z31 and 0.68 and 0.52 at Z39, respectively]. However, adjustment at Z24 was higher for rNDVI (adjR2 = 0.53 and 0.61 for rSPAD and rNDVI, respectively). A single QP model to estimate the dEONR with 58% confidence was adjusted for the Z31 and Z39 growth stages. This indicates that the same calibration for N rate determination based on rSPAD or rNDVI values can be used during stem elongation in spring wheat. This model can be used as an N rate algorithm for applying N fertilizer in-season.Fil: Reussi Calvo, Nahuel Ignacio. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sainz Rozas, Hernan Rene. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Echeverria, Hernan Eduardo. Instituto Nacional de Tecnología Agropecuaria; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Diovisalvi, Nadia Rosalia. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Effect of Cultivar on Chlorophyll Meter and Canopy Reflectance Measurements in Cucumber

Optical sensors can be used to assess crop N status to assist with N fertilizer management. Differences between cultivars may affect optical sensor measurement. Cultivar effects on measurements made with the SPAD-502 (Soil Plant Analysis Development) meter and the MC-100 (Chlorophyll Concentration Meter), and of several vegetation indices measured with the Crop Circle ACS470 canopy reflectance sensor, were assessed. A cucumber (Cucumis sativus L.) crop was grown in a greenhouse, with three cultivars. Each cultivar received three N treatments, of increasing N concentration, being deficient (N1), sufficient (N2) and excessive (N3). There were significant differences between cultivars in the measurements made with both chlorophyll meters, particularly when N supply was sufficient and excessive (N2 and N3 treatments, respectively). There were no consistent differences between cultivars in vegetation indices. Optical sensor measurements were strongly linearly related to leaf N content in each of the three cultivars. The lack of a consistent effect of cultivar on the relationship with leaf N content suggests that a unique equation to estimate leaf N content from vegetation indices can be applied to all three cultivars. Results of chlorophyll meter measurements suggest that care should be taken when using sufficiency values, determined for a particular cultiva

Plant analysis as a tool to determine crop nitrogen status

An effective plant nutrient management strategy optimises nitrogen (N) use efficiency for minimised environmental impact, while ensuring an optimum N status of the crop for good product quality and maximum growth. Soil or plant analysis can be used to evaluate the strategy; however the use of plant analysis for this purpose has been limited. One reason is lack of reliable reference values for the critical concentration needed for optimal growth. This study builds on theories that relate ontogenetic changes in the critical N concentration to changes in the relation between mass and surface area of the entire plant and of individual leaves. Through the establishment of critical N concentrations on the basis of these theories, some of the drawbacks hitherto experienced with plant analysis, such as difficulties in defining growth stage or plant part to sample, can be avoided. The aim of this thesis was to establish critical N concentrations for white cabbage (Brassica oleracea L. var. capitata L. f. alba D.C.) on the basis of these theories. Multi-N-rate and multi-harvest experiments were conducted in the field and in a climate chamber. The results showed that the critical N concentration declined at the same rate (-0.33) as the plant's leaf area ratio (leaf area divided by plant mass), which is in agreement with the 2/3-Power rule or "skin-core" hypothesis. The critical N concentration (% of DM) on a whole plant basis was estimated to 4.5 (W1.5 t ha-1), where W is weight per unit area of plant dry matter exclusive of roots. Moreover, it was concluded that the unshaded horizontally orientated leaves of cabbage can be used for leaf area based plant analysis of individual leaves. The critical N concentration of these leaves expressed on an area basis was found to be 3.7 g N m-2, while that for the whole plant N on a leaf area basis was 4.7 g N m-2. The ratio of these two critical concentrations, 0.8, was similar to the leaf N ratio (leaf N/whole plant N) of young plants before self shading occurs

Micronutrient deficiencies in African soils and the human nutritional nexus: opportunities with staple crops

A synthesis of available agronomic datasets and peer-reviewed scientific literature was conducted to: (1) assess the status of micronutrients in sub-Saharan Africa (SSA) arable soils, (2) improve the understanding of the relations between soil quality/management and crop nutritional quality and (3) evaluate the potential profitability of application of secondary and micronutrients to key food crops in SSA, namely maize (Zea mays L.), beans (Phaseolus spp. and Vicia faba L.), wheat (Triticum aestivum L.) and rice (Oryza sativa L.). We found that there is evidence of widespread but varying micronutrient deficiencies in SSA arable soils and that simultaneous deficiencies of multiple elements (co-occurrence) are prevalent. Zinc (Zn) predominates the list of micronutrients that are deficient in SSA arable soils. Boron (B), iron (Fe), molybdenum (Mo) and copper (Cu) deficiencies are also common. Micronutrient fertilization/agronomic biofortification increases micronutrient concentrations in edible plant organs, and it was profitable to apply fertilizers containing micronutrient elements in 60–80% of the cases. However, both the plant nutritional quality and profit had large variations. Possible causes of this variation may be differences in crop species and cultivars, fertilizer type and application methods, climate and initial soil conditions, and soil chemistry effects on nutrient availability for crop uptake. Therefore, micronutrient use efficiency can be improved by adapting the rates and types of fertilizers to site-specific soil and management conditions. To make region-wide nutritional changes using agronomic biofortification, major policy interventions are needed

Replicability of nitrogen recommendations from ramped calibration strips in winter wheat

Ramped calibration strips have been suggested as a way for grain producers to determine nitrogen needs more accurately. The strips use incrementally increasing levels of nitrogen and enable producers to conduct an experiment in each field to determine nitrogen needs. This study determines whether predictions from the program Ramp Analyzer 1.2 are replicable in Oklahoma hard red winter wheat (Triticum aestivum). Predictions are derived from 36 individual strips from on-farm experiments—two pairs of adjacent strips at each of nine winter wheat fields in Canadian County, OK. The two pairs of strips within each field were between 120 and 155 m apart. Each strip was analyzed three times during the 2006–2007 growing season. Nitrogen recommendations from Ramp Analyzer 1.2 are not correlated even for strips that were placed side by side, and recommendations from strips in the same field show no more homogeneity than randomly selected strips throughout the county. The results indicate that ramped calibration strips are unlikely to produce accurate nitrogen requirement predictions at any spatial scale, whether at the county level or for subsections of a single field. In contrast, a procedure that uses only measures from the plot with no nitrogen and the plot with the highest level of nitrogen applied does show replicability. Thus, improvements in the ramped calibration strip technology are needed if it is to become viable.Fertilizer; Nitrogen; Precision agriculture; Ramped calibration strip; Winter wheat

Growth, productivity, physical and economic optima and yield gaps estimation in wheat (Triticum aestivum L.) through site specific nutrient management approaches under inner-Terai region of Chitwan, Nepal

An on-farm field experiment was accomplished during the winter season of 2018/19 under inner Terai region at Khairahani, Chitwan for evaluating the influence of various site specific nutrient management approaches on growth, yield, optimum fertilizer dose and yield gaps of wheat (Triticum aestivum, L.). The experiment was laid out in Randomized Complete Block Design (RCBD) in three replications with different eight nutrient management practices: T1- farmers fertilization practice (FFP) (52:33:18 kg NPKha-1), T2 - Blanket recommendation (BR) (100:50:25 kg NPK ha-1), T3 - SSNM-NE (110:47:46 kg NPK ha-1),T4 - LCC-N+NE-P&K, T5 - NE-N + farmers -P&K, T6 - LCC- N + farmers–P&K, T7 - Nitrogen Omission Plot (NOPT) + NE- P&K, and T8 - NARC recommendation (120:60:40 kg NPK ha-1). The result findings indicated that the NARC recommendation was comparatively superior over other treatments in terms of plant height, dry matter accumulation, crop growth rate and yield, but the profitability (B:C ratio) was found higher in SSNM-Nutrient Expert recommendation. The physical and economic optimum level of fertilizer for wheat obtained was 135:47.66:43.94 kg NPK ha-1 and 130: 47.86:43.61 kg NPK ha-1, respectively. The yield gaps between farmers practice and SSNM-Nutrient Expert was found to be 110% and 41%, respectively over potential yield of wheat. Thus, it could be suggested that there is great potential to improve the yield of wheat through the NARC recommendation and the SSNM- Nutrient Expert model to raise sustained productivity and income of wheat farmers in inner-Terai region of Nepal. &nbsp

Nitrogen and sulphur management: challenges for organic sources in temperate agricultural systems

A current global trend towards intensification or specialization of agricultural enterprises has been accompanied by increasing public awareness of associated environmental consequences. Air and water pollution from losses of nutrients, such as nitrogen (N) and sulphur (S), are a major concern. Governments have initiated extensive regulatory frameworks, including various land use policies, in an attempt to control or reduce the losses. This paper presents an overview of critical input and loss processes affecting N and S for temperate climates, and provides some background to the discussion in subsequent papers evaluating specific farming systems. Management effects on potential gaseous and leaching losses, the lack of synchrony between supply of nutrients and plant demand, and options for optimizing the efficiency of N and S use are reviewed. Integration of inorganic and organic fertilizer inputs and the equitable re-distribution of nutrients from manure are discussed. The paper concludes by highlighting a need for innovative research that is also targeted to practical approaches for reducing N and S losses, and improving the overall synchrony between supply and demand

Nitrogen dynamics and nitrogen use efficiency of spring cereals under Finnish growing conditions

Nitrogen (N) is one of the main inputs in cereal cultivation and as more than half of the arable land in Finland is used for cereal production, N has contributed substantially to agricultural pollution through fertilizer leaching and runoff. Based on this global phenomenon, the European Community has launched several directives to reduce agricultural emissions to the environment. Trough such measures, and by using economic incentives, it is expected that northern European agricultural practices will, in the future, include reduced N fertilizer application rates. Reduced use of N fertilizer is likely to decrease both production costs and pollution, but could also result in reduced yields and quality if crops experience temporary N deficiency. Therefore, more efficient N use in cereal production, to minimize pollution risks and maximize farmer income, represents a current challenge for agronomic research in the northern growing areas. The main objective of this study was to determine the differences in nitrogen use efficiency (NUE) among spring cereals grown in Finland. Additional aims were to characterize the multiple roles of NUE by analysing the extent of variation in NUE and its component traits among different cultivars, and to understand how other physiological traits, especially radiation use efficiency (RUE) and light interception, affect and interact with the main components of NUE and contribute to differences among cultivars. This study included cultivars of barley (Hordeum vulgare L.), oat (Avena sativa L.) and wheat (Triticum aestivum L.). Field experiments were conducted between 2001 and 2004 at Jokioinen, in Finland. To determine differences in NUE among cultivars and gauge the achievements of plant breeding in NUE, 17-18 cultivars of each of the three cereal species released between 1909 and 2002 were studied. Responses to nitrogen of landraces, old cultivars and modern cultivars of each cereal species were evaluated under two N regimes (0 and 90 kg N ha-1). Results of the study revealed that modern wheat, oat and barley cultivars had similar NUE values under Finnish growing conditions and only results from a wider range of cultivars indicated that wheat cultivars could have lower NUE than the other species. There was a clear relationship between nitrogen uptake efficiency (UPE) and NUE in all species whereas nitrogen utilization efficiency (UTE) had a strong positive relationship with NUE only for oat. UTE was clearly lower in wheat than in other species. Other traits related to N translocation indicated that wheat also had a lower harvest index, nitrogen harvest index and nitrogen remobilisation efficiency and therefore its N translocation efficiency was confirmed to be very low. On the basis of these results there appears to be potential and also a need for improvement in NUE. These results may help understand the underlying physiological differences in NUE and could help to identify alternative production options, such as the different roles that species can play in crop rotations designed to meet the demands of modern agricultural practices.Typellä on kasvintuotannossa ratkaiseva merkitys, sillä sadontuottokyky on kiinteästi sidottu viljan typpiaineenvaihduntaan. Typen puute alentaa huomattavasti satoa. Viljalle käyttökelpoisen typen varastoa maassa pyritään täydentämään lannoituksella. Suomessa yli puolet viljelyalasta on kevätviljoilla, joten typpilannoituksen ympäristövaikutukset ovat nousseet merkittäväksi keskustelun aiheeksi niin Suomessa kuin muuallakin Euroopassa. EU onkin asettanut useita direktiivejä, joilla pyritään rajoittamaan lannoitteiden huuhtoutumista ympäristöön. Näin ollen kasvien typenkäytön tehokkuuden (NUE) parantaminen on ajankohtainen haaste, kun pyritään tuotantomenetelmiä kehitettäessä edistämään ympäristön ekologista kestävyyttä. Tehostamalla kasvien typenottoa ja käyttöä voimme vähentää huuhtoutumiselle alttiin, kasveilta hyödyntämättä jäävän typen määrää maaperässä. Perinnöllisesti tehokkaammin typpeä hyödyntävä lajike parantaa myös viljelyn kannattavuutta. Tutkimuksen päätavoitteena oli määrittää Suomessa viljeltävien kevätviljalajien välisiä eroja typenkäytön tehokkuudessa. Tämän lisäksi pyrittiin määrittämään typenkäytön tehokkuuteen vaikuttavia ominaisuuksia ja niiden vaihtelua lajien välillä ja lajien sisällä. Koe suoritettiin ohra- (Hordeum vulgare L.), kaura- (Avena sativa L.) ja vehnälajikkeilla (Triticum aestivum L.). Kenttäkokeet suoritettiin vuosina 2001-2004, MTT Maa- ja elintarviketalouden tutkimuskeskuksen koekentillä, Jokioisilla. Kasvinjalostuksen vaikutusta typenkäytön tehokkuuteen arvioitiin kaikilla kolmella lajilla, 17-18 lajikkeella, jotka olivat ajanjaksolta 1909-2002. Typpilannoituksen vaikutusta typenkäytön tehokkuuteen ja siihen liittyviin muihin ominaisuuksiin arvioitiin maatiaislajikkeiden ja modernien lajikkeiden välillä kahdella lannoitustasolla (0 ja 90 kg N ha-1). Näissä kokeissa saadut tulokset osoittivat, että uusien lajikkeiden typenkäytön tehokkuus on samaa luokkaa kaikilla kolmella kevätviljalajilla. Kuitenkin laajempi materiaalivalikoima osoitti, että vehnälajikkeiden typenkäytön tehokkuus oli muita lajeja alhaisempi. Kaikilla lajeilla oli selvä yhteys typenkäytön tehokkuuden ja typenoton tehokkuuden (UPE) välillä, kun taas typenkäytön tehokkuuden ja typenhyödyksikäytön tehokkuuden (UTE) välinen yhteys oli selkeä ainoastaan kauralla. Muut typenkuljetukseen liittyvät ominaisuudet osoittautuivat vehnällä muita lajeja heikommiksi. Näiden tulosten perusteella typenkäytön tehokkuuden parantamisella Suomen kasvuoloissa erityisesti vehnällä tuntuisi olevan potentiaalia ja tarvetta. Yleisesti nämä tulokset lajien välisistä eroista typenkäytön tehokkuudessa ja typenkäyttöön liittyvissä muissa ominaisuuksissa osaltaan auttavat viljelyteknisissä toimenpiteissä ja päätöksissä, pohdittaessa esim. viljelykiertoa ja siihen valittavia lajeja

Misc. Pub. 88-1

I submit herewith the annual report of the Agricultural and Forestry Experiment Station, School of Agriculture and Land Resources Management, University of Alaska Fairbanks, for the period ending December 31, 1987. This is done in accordance with an act of the Congress, approved March 2, 1887, entitled "An act to establish Agricultural Experiment Stations, in connection with the Agricultural Colleges established in the several states under the provisions of an act approved July 2,1862, and under the acts supplementary thereto," and also of the act of the Alaska Territorial Legislature, approved March 12,1935, accepting the provisions of the act of Congress. James V. Drew, DirectorStatement of Purpose -- Plant and Animal Sciences -- Forest Sciences -- Resources Management -- Publications -- Financial Statement -- Staf