Nitrogen Management For Maize Research Articles

Optimizing Nitrogen Management in Maize (Zea mays L.) Using Urease and Nitrification Inhibitorss

ABSTRACT Nitrogen (N) is essential for plant growth, and in conventional agriculture, it is usually supplied through fertilization. However, N can be lost through various pathways, reducing its availability to plants and decreasing fertilizer efficiency. This study examined the effects of split urea application and fertilizers containing the nitrification inhibitor 3.4-dimethylpyrazole phosphate (DMPP) and the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT). The fertilizers with inhibitors were applied at both full (100%) and reduced (75%) levels of the standard rate. Conducted over two years, the field trial aimed to assess the capacity of these treatments to mitigate N loss and meet the N requirements of maize effectively. The results of the study revealed that NBPT maintained the required N levels in the soil by meeting the N requirement of maize. On the other hand, DMPP caused N losses due to increasing ammonium levels in the soil during early plant growth stages. NBPT provided the best results in terms of plant yield and N content, whereas DMPP showed lower performance in these parameters. Reduced NBPT doses increased N use efficiency but were less effective in terms of yield compared to full doses. According to the result of the economic analysis, split urea treatment gave better results compared to all treatments. In conclusion, NBPT increased both yield and N use efficiency by regulating N release.

Cold Climate Factors in Nitrogen Management for Maize

Among essential crop nutrients, nitrogen is the greatest management challenge in maize (Zea mays L.) production due to high requisite rates as well as dynamic transformations and losses. Climate plays a role in N management through changes in crop calendars, soil properties, agronomic practices, and yield effects. This study focuses on climate influences on maize N management and the objectives are to (i) review cold climate factors impacting economic optimum N rates (EONR), (ii) discuss approaches and climate considerations in estimating optimum N rates, and (iii) illustrate unexplored climate aspects related to optimum N rate assessment. Cold climate effects are expressed through inherent soil properties, agronomic management, and N fertilizer management. Most current N rate calculators do not explicitly account for climate factors, but implicitly integrate them through regional calibrations. Yield and EONR data from the US Corn Belt region indicate a positive correlation where lower means are associated with colder climates. High variability within climate regions is explained by differences in annual production environments, notably seasonal weather. Soil health models show that colder climates in the US are associated with higher stocks of soil organic matter, especially labile fractions. Adapt-N model simulations of a colder (North Central Wisconsin; 45.50, −89.70) and warmer (South Central Illinois; 38.50, −89.70) Corn Belt location show that higher soil organic N stocks do not increase crop N availability, presumably due to temperature-constrained N mineralization rates. The EONR for the colder site is 58 kg N ha−1 lower than the warmer site, which is well explained by differences in yield potential. Overall, abductive inferences suggest that colder climates are generally associated with higher levels of organic N stocks, but lower yields and crop N demands lessen EONRs. Seasonal weather and interactions with soil and agronomic factors also critically impact EONR, which can be assessed with model-based decision tools.

Contemporary nitrogen management in maize (Zea mays)–Indian mustard (Brassica juncea) cropping system for maximizing yield, water productivity and profitability

A field experiment was conducted during 2018–19 and 2019–20 at the research farm of ICAR-Directorate of Rapeseed-Mustard Research, Bharatpur, Rajasthan to evaluate the effect of organic and inorganic nitrogen sources on yield, water productivity, system productivity and economics of maize (Zea mays L.)-mustard [Brassica juncea (L.) Czern.] cropping system. The experiment was conducted in split-plot design with recommended levels of fertilizers (RDF)/FYM/biofertilizer/mustard straw/Jivamrat in main-plots and recommended doses of nitrogen (RDN) 100, 125 and 150% in sub-plots to maize and Indian mustard and replicated thrice. Application of RDF + FYM @2.5 t/ha + Azotobacter + mustard straw @2.5 t/ha recorded highest SCMR (41.2), leaf area index (4.42), number of siliqua/ plant (440.7), number of seeds/siliqua (18.4), test weight (5.83 g) and seed yield (3.36 t/ha) of mustard. Application of RDN 150% recorded highest physiological and yield attributes and seed yield (3.22 t/ha) of mustard. Results also showed the highest physiological and yield attributes and grain yield (3.73 t/ha) of maize with RDF+FYM @2.5 t/ ha+Azotobacter+mustard straw @2.5 t/ha. System productivity (4.84 t/ha) and water productivity (2.14 kg seed/m3) were found higher with RDF+FYM @2.5 t/ha +Azotobacter+mustard straw @2.5 t/ha and RDN 150%. The highest net monetary return 51715, 81040 and 132755 `/ha and B:C ratio 3.09, 3.22 and 3.15 were recorded for maize, mustard and system with RDF+FYM @2.5 t/ha+Azotobacter+mustard straw @2.5 t/ha and RDN 150%, respectively. Thus, integrated use of RDF+FYM @2.5 t/ha+Azotobacter+mustard straw @2.5 t/ha with RDN @150% improved maize–mustard system yield and profitability under semi-arid climates.

Effect of residue and nitrogen management in maize (Zea mays) on mustard (Brassica juncea) productivity and profitability under conservation agriculture

A field experiment was conducted during 2018–19 and 2019–20 to assess the influence of precision nitrogen management options in preceding maize (Zea mays L.) on succeeding mustard (Brassica juncea L.) under conservation agriculture in sandy loam soil of Delhi. The experiment had two main plots of with residue (WR) and without residue (WoR) retention and four sub-plot treatments of N management applied in maize {recommended dose of N (RDN), 33, 50 and 70% basal RDN +green seeker (GS) based N application} and uniform recommended dose of 90 kg N/ha was applied for mustard in all treatments. A positive response to residual plus directly applied N and residue application was observed on growth, dry matter accumulation, yield attributes, yield and nutrient uptake of mustard. On a pooled mean basis, crop residue mulching enhanced 7.1 and 8.3% in seed and stalk yield of mustard with 9.4 and 5.2%higher net returns and B:C ratio. The 50% basal RDN + GS guided N applied treatment on pooled basis gave 5.9 and 5.2% higher seed and stalk yield and 7.7 and 7.9% higher net returns and B:C ratio compared to conventional RDN. The highest land productivity in mustard was also obtained with residue retention (`654/day) and 50% RDN +GS (`674/day). Overall, the study concluded that zero tillage with maize residue mulching and recommended nitrogen application in mustard in rotation with 50% basal RDN+GS guided N applied maize improves the crop growth, yield attributes, yield and net returns of mustard, and could be implemented in maize-mustard cropping system under resource-poor semi-arid conditions

The lagging movement of soil nitrate in comparison to that of soil water in the 500-cm soil profile

The combination of forage-crop rotation with conservation tillage has long been known to result in proven productivity and sustainability, but less information is available on the influence of long-term conservation tillage practices on the movement of soil water and residual nitrate at deep soil depths in forage-crop rotation systems. In this study, we measured the changes in soil water storage, residual soil nitrate accumulation and their relationship to study the long-term effects of tillage and mulching practices on regional nitrogen management in maize (Zea mays L.)-wheat (Triticum aestivum L.)-common vetch (Vicia sativa L., annual legume forage) rotation system. Soils were collected from the 500-cm soil profile at the harvest stage of the maize and common vetch after 19 years of continuous conventional tillage (T), conventional tillage followed by straw mulching (TS), no tillage (NT), and no tillage followed by straw mulching (NTS) on the Loess Plateau, China. The results showed that the NT practices increased soil water storage by 3.07% compared with the T practices in the maize field, mulching practices increased soil water storage by 3.47% compared with no mulching practices in the common vetch field, and the improvement effect was mainly concentrated in the deep soil layer (150–500 cm). When compared with no mulching, straw mulching practices increased residual soil nitrate accumulation by 51.20 kg ha−1 at shallow soil depths (0–120 cm) but decreased this accumulation by 206.09 kg ha−1 at deep soil depths (120–500 cm) in the maize field; however, straw mulching decreased nitrate accumulation by 16.25 kg ha−1 throughout the whole profile (0–500 cm) in the common vetch field. The NT practices decreased residual soil nitrate accumulation by 131.65 kg ha−1 compared with the T practices in the maize field but had no effects on the common vetch field in the 0–500-cm soil profile. Greater changes in soil residual nitrate accumulation appeared at depths of 200–500 cm than at other depths. Moreover, according to structural equation model, nitrite accumulation was limited by soil water storage. Soil nitrate peaked at deeper soil depths in the NT (90–120 cm) and TS (250–300 cm) treatments than in the T treatment (60–90 cm), whereas the NTS treatment resulted in no nitrate accumulation peak across the whole soil profile. Soil water recharge and depletion were deeper in the NT and TS treatments than in the T treatment, and this effect could limit the further leaching of soil nitrate into deep soil. The depth of soil water recharge was deeper than the depth of nitrate accumulation, and the vertical movement speed of soil residual nitrate was slower than that of soil water. Therefore, the downward movement of soil nitrate lagged behind that of soil water. Together, these results demonstrated that the NTS treatment exerted the strongest effect on maintaining soil water and decreasing residual nitrate accumulation at deep soil depths, which will be favorable for improving regional N management and assessing N budgets in agroecological systems on the Loess Plateau.

Comparative analyses of variable and fixed rate irrigation and nitrogen management for maize in different soil types: Part II. Growth, grain yield, evapotranspiration, production functions and water productivity

Comparisons of variable rate irrigation (VRI) and variable rate fertigation (VRF) with fixed rate irrigation (FRI), no irrigation (NI) and conventional fertilizer management for maize (Zea mays L.) under three soil types (S1, S2 and S3) were made for three years (2015, 2016 and 2017). The research quantified and compared maize growth and development [leaf area index (LAI) and plant height], grain yield, crop evapotranspiration (ETc), irrigation-yield production functions (IYPF), evapotranspiration-yield production functions (ETYPF) and crop water productivity (CWP) under VRI, FRI and NI at fixed rate fertigation (FRF), VRF and pre-plant nitrogen (PP) management in the same environment and under the same agroomic management practices. The VRF treatment used 20% less fertilizer as compred with PP and FRF treatment without significantly (P > 0.05) reducing the grain yield. In the higher elevation soil S1, the grain yield was not significantly different (P > 0.05) between FRI and VRI treatments. However, in S2 and S3 which have lower elevation, yield in FRI was 43% and 55% greater than the yield in VRI, respectively. On average, under VRI management total irrigation amount 24% lower than FRI in S1, with only 4% reduction in yield as compared with FRI. Soil type impacted the response of maize grain yield to ETc and the responses also varied between FRI and VRI. For all soil types and years, higher ETc was observed in FRI treatment, except in 2015 for S1 and S2 where highest ETc was observed in VRI. FRI had greater productivity per unit of ETc than VRI. Observing the linear relationship of the pooled data for each soil type, a 25.4 mm of ETc (beyond the intercept) resulted in 0.48 and 0.35 ton ha−1 maize yield for FRI and VRI treatment, respectively, in S1; 0.75 and 0.45 ton ha−1 for FRI and VRI, respectively, in S2; and 0.71 and 0.43 ton ha−1 for FRI and VRI, respectively, in S3. VRI strategy increased the variability in grain yield, ETc and CWP as compared with FRI management. S1 had the lowest grain yield variability as compared with S2 and S3. The coefficient of variation (CV) of grain yield ranged from 8% in S1-FRI to as high as 35.3% in S3 VRI. FRI treatment in all soil types and years had less variation in yield as compared with VRI. Soil type had impact on CWP. On a three-year average basis, CWP was 2% higher in VRI in S1 whereas 11% lower in S2 and S3 than FRI CWP. Stronger grain yield response to irrigation and ETc (IYPF and ETYPF) were observed for FRI than VRI and NI at all nitrogen levels. The results of this research indicated that, in most cases, FRI had superior performance in terms of maintaining optimum crop yield and reducing yield variations than VRI. VRI management based on soil water status has potential of maintaining maize grain yield and improving CWP as compared with FRI in certain conditions or soil types such as in S1. However, further research is needed to validate/justify its adoption for the fields with significant spatial soil heterogeneity (both in horizontal and vertical domains) and to understand the economics of VRI-VRF systems. These results would be beneficial for maize growers and their advisors in terms of understanding the productivity responses to water under VRI and FRI management strategies with VRF, FRF and PP nitrogen application.

Comparative analyses of variable and fixed rate irrigation and nitrogen management for maize in different soil types: Part I. Impact on soil-water dynamics and crop evapotranspiration

Understanding the soil-water dynamics and maize evapotranspiration (ETc) under variable rate irrigation (VRI) and variable rate fertigation (VRF) management with respect to soil spatial variability constitutes the basis for developing effective variable rate water and nitrogen management strategies. This long-term research was designed to quantify and compare the soil-water dynamics, including available water (AW), and ETc during vegetative and reproductive growth periods of VRI, fixed rate irrigation (FRI) and no-irrigation (NI) under fixed rate fertigation (FRF), VRF and pre-plant (PP) nitrogen management in three different soil types [Crete silt loam (S1); Hastings silty clay loam (S2) and Hastings silt loam (S3)] with different topography in the same field under the same environmental and management conditions. The research was conducted in the Irmak Research Laboratory in south central Nebraska, U.S.A., in 2015, 2016 and 2017 maize (Zea mays L.) growing seasons under a variable-rate linear move sprinkler irrigation system. No effect of irrigation and nitrogen fertilizer on AW was observed in the vegetative period. Overall, greater AW was observed in S3 as compared with S1 and S2 due to lower elevation. Maize ETc during the vegetative period was significantly (P < 0.05) impacted by soil type in all three years and by nitrogen treatment in two of the three years. The vegetative ETc in S1 was 27 and 19 mm greater than S2 and S3, respectively, for the pooled 2015, 2016 and 2017 data. During the reproductive period, both ETc and AW were impacted by nitrogen and irrigation treatments, but differently in different soil types and years. Average reproductive ETc for FRI and VRI in 2015, 2016 and 2017 was 175 and 178 mm; 294 and 241 mm; 258 and 206 mm, respectively. Averaged across three years, ETc under FRI was significantly (P < 0.05) greater than in VRI; however, in 2015, no significant difference (P > 0.05) in ETc between FRI and VRI was observed in any soil type. Similarly, in 2017, no significant difference in reproductive ETc was observed between VRI and FRI in S1. During reproductive period, averaged across years, soil types and irrigation treatments, the PP nitrogen treatment had greater ETc and lower AW than VRF and FRF. The results indicate that vegetative period ETc was primarily affected by soil type, weather conditions (evaporative demand and soil wetting) and nitrogen fertilizer application timing. The findings of this research showed that soil-water dynamics is a strong function of not only management practices (irrigation and nitrogen treatments), but also soil type, topography and soil physical properties, which all need to be taken into account for effective management of VRI and FRI under VRF, FRF or PP nitrogen management in different soil types. This research quantified the impact of these management practices on soil-water dynamics and ETc which can be used as a guidance.

Influence of intercropping system and integrated nitrogen management in maize (popcorn) (Zea mays everta L.) - chickpea (Cicer arietinum L.) intercropping under middle Gujarat conditions

A field experiment was conducted at Agronomy Farm, Anand Agricultural University, Anand to find out influence of intercropping system and integrated nitrogen management in maize (popcorn) (Zea mays everta L.) - chickpea (Cicer arietinum L.) intercropping during rabi season of 2017-18 and 2018-19. There were sixteen treatment combinations comprised of four intercropping systems viz., S1: maize sole, S2: chickpea sole S3: maize - chickpea 1:1 and S4: maize - chickpea 2:2 placed as main plot treatments and four integrated nitrogen management viz., N1: 100 % RDN (Recommended Dose of Nitrogen), N2: 75 % RDN + 25 % vermicompost N3: 75 % RDN + 25 % FYM and N4 : 50 % RDN + 25 % vermicompost + 25 % FYM set as sub plot treatments in split plot design with four replications. The soil of experimental plot was loamy sand in texture. The soil was low in available nitrogen and medium in available phosphorous and in potash. Results revealed that maize crop intercropped with chickpea with 1:1 ratio recorded significantly higher cob length, cob girth, weight of cob, number of grains/cob, grain yield and stover yield of maize, and significantly higher plant height, number of nodules/plant, number of pods /plant, seed yield, dry fodder yield and harvest index of chickpea and higher maize equivalent yield. Integrated nitrogen management had remarkable impact on growth parameters, yield attributes and yield of maize - chickpea intercropping and significantly higher plant height, cob length, cob girth, weight of cob, number of grains /cob, grain yield, stover yield, protein content of maize, and number of nodules/plant, number of pods/plant, seed yield and haulm yield, harvest index, protein content of chickpea as well as maize equivalent yield were obtained with the crops fertilized with 50 % RDN + 25 % vermicompost + 25 % FYM.

Conservation agriculture and nitrogen management in maize–wheat cropping system: effect on growth, productivity and economics of wheat

A study was conducted at ICAR-Indian Agricultural Research Institute, New Delhi to assess the effect of six combinations of tillage and crop establishment techniques, i.e. conventional tillage-flat-bed (CT-F), CT-raised-bed (CT-B), zero tillage-flat-bed with crop-residue (ZT-F+R) and without crop-residue (ZT-F), ZT-raised-bed with crop residue (ZT-B+R) and without crop-residue (ZT-B) in combination of four levels of fertilizer-nitrogen (N; 0, 60, 120 and 180 kg N/ha) on growth, yield and economics of wheat (Triticum aestivum L. emend. Fiori & Paol) in conservation agriculture based maize (Zea mays L.)-wheat cropping system. The performance of the wheat in terms of growth, yield and net returns was observed statistically similar under different tillage and establishment techniques but it was differed significantly (p ≤ 0.05) due to different levels of N. Crop-residue applied treatments (ZT-F+R/ZT-B+R) improved the grain and straw yields over without crop-residue applied ZT (by 5.2 and 3.6% under flat-planting; and 7.7 and 4.1% under raised-bed planting systems, respectively) and CT practices (by 12.0 and 5.4% under flat-planting and 8.1 and 3.4% under raised-bed planting systems, respectively). The ZT technology reduced the cost of cultivation by 9.8% and improved the net profits by 9.0% over the CT practices. Further, recycling of crop residue under ZT practices (ZT-F+R/ZT-B+R) not only produced the maximum grain yield (8.0-12.0% higher) but also generated either equal or higher net profits over the CT practices. The growth, yield attributes, grain yield, straw yield and net returns were increased significantly up to 120 kg N/ha, though the maximum values of most of these parameters were recorded at 180 kg N/ha. Therefore, it can be concluded that ZT practices along with crop residues and 120 kg N/ha could be adopted to make the wheat cultivation more remunerative and sustainable.

Determination of the post-anthesis nitrogen status using ear critical nitrogen dilution curve and its implications for nitrogen management in maize and wheat

Abstract Nitrogen (N) accumulation in plant reproductive organs during the post-anthesis growth phase of maize and wheat plays a crucial role in the formation of grain yield and quality. However, little is known about the effect of crop pre-anthesis and post-anthesis N status on ear N accumulation (NAE). This study endeavored to extend the crop N dilution theory already developed for vegetative growth period to determine ear critical N concentration (%NcE) during post-anthesis period of crop growth for analyzing the difference of NAE under various N levels. The data including the weight of dry mass (W) and N concentration of entire plant and ear, post-anthesis plant N uptake (PANU) from soil, grain number (GN), and grain weight (GW) were collected on wheat (two cultivars) and maize (three cultivars) from eight N rates (0–300 kg N ha−1) field experiments. The results revealed that the process of %N dilution exists in ear and it is plausible to extend the concept of %NcE curve till crop post-anthesis period. The %NcE curves as function of ear dry mass (WE) of wheat (%NcE = 2.85WE-0.17) and maize (%NcE = 2.22WE-0.26) were lower than those developed in maize and wheat on whole plant basis. This study revealed that the ear has the potential to diagnose ear N status under different N conditions and the increases in ear N nutrition index (NNIE) during the post-anthesis period with increasing N rate were well synchronized with plant NNI (NNIp) at anthesis. GN and GW of maize and wheat showed significantly positive correlation with NNIp at anthesis and NNIE at maturity under N-limiting treatments, and GN and GW could keep relatively stable under non-N limiting treatments. NNIp and NNIE showed the potential capacity to predict GN and GW of maize and wheat under N limiting condition. Ear critical N accumulation (NAcE) was calculated using ear Nc curve to investigate the differences mechanism of NAE under different N conditions. The difference of NAcE under different N treatments was deduced from the pre-anthesis N status of maize and wheat by determining GN. The ear N deficiency (NDE) between NAcE and NAE was co-regulated by plant pre-anthesis and post-anthesis N status, which in turn have potential to explain the variance of GW at maturity in both crops. The significantly attenuated effect of pre-anthesis N deficiency on ear potential N demand in maize and wheat indicated that the post-anthesis N management must consider the pre-anthesis N status and the corresponding reduction of the post-anthesis N input to prevent N loss under N limiting treatment in both crops. Maize was more dependent on post-anthesis N status while wheat was more reliant on pre-anthesis N status for satisfying ear growth and producing optimum GN owing to the differential values of PANU/NAE in maize and wheat during post-anthesis period. This study provides a new viewpoint on post-anthesis N management of maize and wheat for enhancing N use efficiency and grain yield.

Nitrogen Management in Maize Under Rainfed Conditions in the Brazilian Semiarid Region

Zea mays L. presents socioeconomic and cultural importance for the Northeast region of Brazil, its yield is directly related to the productive system, to the edaphoclimatic conditions and to the soil management. The aim of this work was to evaluate the development and the yield of maize under different nitrogen doses in rainfed conditions in the Brazilian semiarid. The experimental design was in randomized blocks, with four treatments and five replications, totalizing 20 experimental plots, with 24 plants each. The treatments were: T1 (0 kg ha-1 of N); T2 (40 kg ha-1 of N); T3 (60 kg ha-1 of N) and T4 (80 kg ha-1 of N). Were evaluated: plant height, culm diameter and number of leaves at 30, 45, 60, 75 and 90 days after emergence; leaf temperature, stomatal conductance, transpiration, liquid photosynthesis and intercellular carbon concentration at 65 days after emergence; yield, shoot dry mass and nitrogen content in the soil after harvest. The different nitrogen doses significantly influenced the plant height, culm diameter and the number of leaves in the different evaluation periods, also influencing the nitrogen levels in the soil after the harvest. There was no difference among treatments for the yield, the registered average was 5,205 kg ha-1. The development of the crop and the nitrogen absorption may have been influenced by the water deficit during the crop cycle. The maize presented better agronomic performance with the dose of 60 kg ha-1 of nitrogen.

Effects of irrigation, crop residue mulch and nitrogen management in maize (Zea mays L.) on soil carbon pools in a sandy loam soil of Indo-gangetic plain region

Different land use management practices e.g. native forest vegetation, pastures and the agricultural management practices (e.g. tillage, cropping system, crop residue mulching and fertilizer and manure application) influence the soil organic carbon pools, which has short term and long term implications on soil carbon dynamics. Field experiments were conducted in a sandy loam soil of the Indian Agricultural Research Institute, New Delhi research farm during the kharif season (July to October) of 2012 and 2013 with the objective to study the short term (2 years) impact of irrigation, crop residue mulch and nitrogen management in maize on soil organic carbon pools and to identify the best management practice in terms of Carbon Management Index (CMI). Maize (cv. HQPM 1) was grown in a split-split plot design with two levels of irrigation (irrigated and rainfed) as main factor, two levels of mulch (No mulch and wheat residue at a rate of 10 Mg/ha as mulch) as sub factor and three levels of nitrogen (0, 75 and 150 kg N/ha) as subsub factor. The results showed that total organic carbon (TOC) increased by 40.5% in irrigation treatment compared to the rainfed treatment for the 0–5 cm soil depth after 2nd year of cropping. Application of crop residue mulch significantly increased the TOC concentration by 14.9% at 0–5 cm soil depth compared to the no mulch treatment. Crop residue mulch also significantly increased carbon stratification ratio (SR) by 9.2% compared to no mulch treatment for the same depth. Nitrogen application at 150 kg/ha significantly increased TOC concentration at 0–5 cm soil depth by 22.2% and 7.8% over control and 75 kg/ha, respectively. Water stable aggregate associated carbon concentration in large macro-aggregates and micro-aggregates increased significantly by 16.7% and 11.8%, respectively due to crop residue mulching. Application of crop residue mulch resulted in significant increase in labile and non-labile pools of carbon at 0–5 cm soil depth compared to the no mulch treatment, and among the labile pools of carbon, the maximum increase was recorded in very labile (VL) pools. The Carbon Lability Index (CLI) decreased whereas Carbon Pool Index (CPI) and Carbon Management Index (CMI) increased due to irrigation and crop residue mulch application. Application of 75 kg N/ha resulted in significantly higher CMI than that of 150 kg N/ha at 0–5 and 5–15 cm soil depth. So maize may be grown under irrigated condition with wheat residue mulch at a rate of 10 Mg/ha and 75 kg N/ha to achieve higher total organic carbon pool and labile pools of carbon, better Carbon Management Index.

Nitrogen management in maize based legume intercropping system

Nitrogen management in maize based legume intercropping system

Maize‐N: A Decision Tool for Nitrogen Management in Maize

Nitrogen fertilizer efficiency has a large influence on profit, energy efficiency, N losses to the environment, and greenhouse gas emissions in maize (Zea mays L.) production. Our purpose was to develop a robust decision‐support tool to help inform N fertilizer recommendations and to compare performance of this tool relative to existing recommendation approaches. Maize‐N is a simulation model for estimating economically optimum N fertilizer rates (EONR) for maize. The model estimates the EONR based on uptake efficiency of the applied N, expected yield response, market prices of grain and N fertilizer, and mechanistic components of soil N mineralization. Uptake efficiency and expected yield response are derived from a database of yield response to applied N from field experiments in the United States, Asia, and South America. The model is responsive to: (i) soil properties and indigenous soil N supply capacity, (ii) local climatic conditions and yield potential, (iii) crop rotation (including type and yield of previous crop), (iv) tillage method and timing of tillage operations, and (v) fertilizer formulation, application method, and timing. Validation of Maize‐N across N management regimes and environments in the western U.S. Corn Belt indicated reasonable agreement between observed and measured values of EONR (RMSE of 21 kg N ha−1), which compares favorably with RMSE values of 33 to 61 kg N ha−1 for other methods based on empirical relationships derived from regional field tests in Kansas, Missouri, Nebraska, South Dakota, and Iowa.

Manejo do solo e do nitrogênio em milho cultivado em espaçamentos reduzido e tradicional

Práticas agronômicas que ajudem o agricultor a elevar a produtividade e a diminuir os custos de produção devem ser estudadas para garantir a sustentabilidade da agricultura. Assim, desenvolveu-se um experimento com o objetivo de estudar o efeito do manejo do solo, do nitrogênio e do espaçamento entrelinhas na cultura do milho em dois anos agrícolas. O experimento foi instalado sobre um Latossolo Vermelho Distrófico em delineamento experimental de blocos casualizados em esquema fatorial 3 x 5 x 2 com quatro repetições. Os tratamentos foram constituídos pela combinação de três manejos do solo (grade aradora + grade niveladora, escarificador + grade niveladora e plantio direto), cinco épocas de aplicação do nitrogênio [testemunha sem N, 120 kg ha-1 na semeadura (S), 120 kg ha-1 no estádio fenológico V6, 30 kg ha-1 (S) + 90 kg ha-1 em V6, 30 kg ha-1 (S) + 45 kg ha-1 em V4 + 45 kg ha-1 em V8] e dois espaçamentos entrelinhas (0,45 e 0,90 m) com população fixa. Concluiu-se que o sistema plantio direto promoveu maior população final de plantas e maior produtividade de grãos; a aplicação precoce de todo o N proporcionou produtividade de grãos semelhante aos manejos com parcelamento, e o espaçamento de 0,90 promoveu maior massa seca dasplantas quando o preparo foi feito com grade aradora + niveladora.

Evaluation of leaf-colour chart for need-based nitrogen management in maize (Zea mays) grown under irrigated condition of Mollisols

A field study was conducted at Pantnagar, Uttarakhand, during the rainy (kharif) season of 2013 and 2014 us- ing leaf-colour chart (LCC) as a tool to know nitrogen demand in maize (Zea mays L.) crop and to evaluate and establish LCC threshold value for saving fertilizer N and achieve higher grain. The LCC-treated plots showed higher increase in grain yield/kg N applied over fixed time interval of N treatments. Using of LCC score 3.0 with 90 kg N/ha showed grain-yield equivalent to 120 and 150 kg N/ha applied at fixed time interval and gave higher re- covery efficiency to the tune of 12.118.1 unit and 4.15.1 kg higher grain yield/kg fertilizer N applied, whereas LCC 5.0 resulted in significant higher grain yield. Application of fertilizer N with 1.0 unit increase in LCC score sig- nificantly enhanced grain yield but no response of fertilizer N was seen when applied at reproductive stage. Soil- available N increased significantly with increasing the LCC values and was significantly superior at LCC &lt; 5.0 fol- lowed by 150 kg N/ha applied at fixed time interval. Leaf-colour chart-based N management reduced anthesis silking interval by 0.21.4 days compared to fixed time interval. Strong correlation was obtained for LCC score with N content and grain yield at the reproductive stage. Leaf-colour chart values against grain yield indicated that LCC 4.6 at vegetative stage and LCC 4.9 at reproductive stage can guide crop demand-driven N application to en- hance yield and saving N in maize under irrigated condition of Mollisols in tarai region.