Sorghum Plots Research Articles

Changes in soil physical and mechanical properties under different tillage and cropping systems in alfisol soil of southwestern Nigeria

Sustainable agricultural strategies such as conservation agriculture (CA) and integrated land management are required to mitigate land degradation and food insecurity. This study was conducted to investigate the effects of different cropping systems: sole sorghum (SOR), sole cowpea (COW), sole soybean (SOY), sorghum-cowpea intercrop (SC), and sorghum-soybean intercrop (SS); and tillage practices: conventional tillage (CT), no tillage (NT), and compacted no till (NTc) on physical and mechanical properties of an Alfisol in Southwestern Nigeria. The experimental layout comprised a split plot design accommodating the 3 tillage and 5 cropping systems in a randomized complete block design with three replications. Undisturbed soil samples were collected from 0 to 15 ​cm, and 15–30 ​cm soil layers for the determination of soil bulk density (BD), total porosity (TP), and unconfined compressive strength (quf). The results showed that bulk density was lower, while total porosity was higher under intercrops than monocrops in all the tillage treatments. Conventional tillage had the least BD compared to no tillage and compacted no till plots. Soil vane shear strength (Ʈ) and unconfined compressive strength (quf) were generally lower under the intercrops than the sole sorghum plots. Averaged over the two soil depths, the mean soil quf of SS intercrop was 1.28 times lower than the mean soil quf of SOR but was 1.06 times higher than the mean soil quf of SOY. SC intercrop had a 14.20% and a 9.15% lower average soil quf than SOR and COW in 2019. Unconfined compressive strength and vanes shear strength significantly positively correlated with BD and negatively with TP, organic carbon (OC), organic matter (OM), and total nitrogen (N) in both cropping years. The research demonstrates that farming approaches that integrate soil cover preservation and minimal soil disturbance with diverse cropping systems improve soil physical and mechanical behavior.

Row selection in remote sensing from four-row plots of maize and sorghum based on repeatability and predictive modeling.

Remote sensing enables the rapid assessment of many traits that provide valuable information to plant breeders throughout the growing season to improve genetic gain. These traits are often extracted from remote sensing data on a row segment (rows within a plot) basis enabling the quantitative assessment of any row-wise subset of plants in a plot, rather than a few individual representative plants, as is commonly done in field-based phenotyping. Nevertheless, which rows to include in analysis is still a matter of debate. The objective of this experiment was to evaluate row selection and plot trimming in field trials conducted using four-row plots with remote sensing traits extracted from RGB (red-green-blue), LiDAR (light detection and ranging), and VNIR (visible near infrared) hyperspectral data. Uncrewed aerial vehicle flights were conducted throughout the growing seasons of 2018 to 2021 with data collected on three years of a sorghum experiment and two years of a maize experiment. Traits were extracted from each plot based on all four row segments (RS) (RS1234), inner rows (RS23), outer rows (RS14), and individual rows (RS1, RS2, RS3, and RS4). Plot end trimming of 40cm was an additional factor tested. Repeatability and predictive modeling of end-season yield were used to evaluate performance of these methodologies. Plot trimming was never shown to result in significantly different outcomes from non-trimmed plots. Significant differences were often observed based on differences in row selection. Plots with more row segments were often favorable for increasing repeatability, and excluding outer rows improved predictive modeling. These results support long-standing principles of experimental design in agronomy and should be considered in breeding programs that incorporate remote sensing.

EVALUATION OF THE EFFECTIVENESS OF SHREDDED NEEM SEEDS (AzadirachtaIndica A. Juss) IN THE MANAGEMENT OF SPODOPTERA FRUGIPERDA J. & SMITH (Lepidoptera: Noctuidae) IN SORGHUM CULTIVATION IN MALI

As part of the alternative management of Spodoptera frugiperda and for food security, a test of the effectiveness of crushed neem in sorghum cultivation was carried out at the Regional Agricultural Research Center of Sotuba during the rainy season from 2020 to 2022. The objectives were: to identify an effective intervention threshold against Spodoptera frugiperda compatible with the use of crushed neem seeds; to determine an effective spraying frequency of neem seed grind and to determine the effect of neem seed grind on sorghum grain yield. A total randomization design with five treatments in five repetitions was carried out. A significant average reduction in the population of the lowest Spodoptera frugiperda larvae was recorded by 0.00 larva/plant, an average incidence of 5.0948% and an increase in the highest average grain yields of 1703 kg-1ha and of straw of 4410 kg-1ha in the sorghum plots under protection. The use of shredded neem seeds can be recommended for the management of Spodoptera frugiperda in sorghum cultivation in Mali.

Insect Feeding on Sorghum bicolor Pollen and Hymenoptera Attraction to Aphid-Produced Honeydew.

Pollinators are declining globally, potentially reducing both human food supply and plant diversity. To support pollinator populations, planting of nectar-rich plants with different flowering seasons is encouraged while promoting wind-pollinated plants, including grasses, is rarely recommended. However, many bees and other pollinators collect pollen from grasses which is used as a protein source. In addition to pollen, Hymenoptera may also collect honeydew from plants infested with aphids. In this study, insects consuming or collecting pollen from sweet sorghum, Sorghum bicolor, were recorded while pan traps and yellow sticky card surveys were placed in grain sorghum fields and in areas with Johnsongrass, Sorghum halepense to assess the Hymenoptera response to honeydew excreted by the sorghum aphid (SA), Melanaphis sorghi. Five genera of insects, including bees, hoverflies, and earwigs, were observed feeding on pollen in sweet sorghum, with differences observed by date, but not plant height or panicle length. Nearly 2000 Hymenoptera belonging to 29 families were collected from grain sorghum with 84% associated with aphid infestations. About 4 times as many Hymenoptera were collected in SA infested sorghum with significantly more ants, halictid bees, scelionid, sphecid, encyrtid, mymarid, diapriid and braconid wasps were found in infested sorghum plots. In Johnsongrass plots, 20 times more Hymenoptera were collected from infested plots. Together, the data suggest that sorghum is serving as a pollen food source for hoverflies, earwigs, and bees and sorghum susceptible to SA could provide energy from honeydew. Future research should examine whether planting strips of susceptible sorghum at crop field edges would benefit Hymenoptera and pollinators.

Gender gaps in sorghum productivity: evidence from male- and female-managed plots in Uganda

ABSTRACT Gender gaps in crop productivity can negatively affect rural socio-economic development of agrarian economies with serious implications for food and nutrition security. We assess productivity in male- and female-managed sorghum plots in Lira, Kumi, and Serere districts in Uganda. We find male-managed plots have higher productivity of 850.6 kgs/ha compared to female-managed plots (832.6 kgs/ha). An observed mean gender gap of 18% due to structural advantages of male plots (57%), structural disadvantages of female plots (33%), and endowment (10%) exists. Therefore, interventions aimed at promoting equitable access to institutional support services are paramount in reducing structural disadvantages against female farmers.

Land Equivalent Ratio of Cowpea–Sorghum Relay Intercrop as Affected by Different Cattle Manure Application Rates Under Smallholder Farming System

Poor soil fertility is a major challenge to crop production in the communal farming areas of Zimbabwe. Intercropping legumes and cereals is a common soil fertility management technology among the farmers. A 3-year field experiment was conducted to evaluate cowpea–sorghum relay intercropping advantages in response to different cattle manure application rates. A 3 × 4 factorial experiment laid in a completely randomized block design (CRBD) with three replicates was conducted. The treatments were three cropping systems (sorghum sole, cowpea sole, and cowpea–sorghum intercrop) and four cattle manure application rates (0, 50, 75, and 100%). Crop growth rate (CGR), grain yield, harvest index (HI), relative competitive ability of each crop, and land equivalent ratio (LER) were measured. Analysis of variance and non-linear regression analyses were done to determine the yield benefits of cowpea–sorghum intercrop and estimate the relative competitive ability, respectively. Application of >75% cattle manure in a cowpea–sorghum intercrop enhanced the sorghum grain yield (75%) and HI (125%) of unmanured cowpea–sorghum plots. Cowpeas had higher CGR (159.6, 166.7 and 149.5 g m−2 day−1 at 7, 21, and 35 days after planting, respectively) at >75% cattle manure application rates on both intercrop and sole cropping than sorghum but with lower grain yield (1.4 t ha−1). Intraspecific competitive stress in sorghum was reduced at a high (>75%) quantity of manure applied. The effects of the intraspecific competition in cowpea were stronger (0.693) on grain yield than biomass at >75% manure application rates. The LER was >1 in all the treatments and was highest (2.73) under the cowpea–sorghum relay intercrop without cattle manure. Cattle manure application at 75% in a cowpea–sorghum intercrop enhanced the grain yield in sorghum and vegetative growth in cowpeas. It is therefore recommended to use the >75% cattle manure application rate in the intercrop if one wants higher grain in sorghum and high biomass in cowpeas possibly for fodder. Further studies are recommended to quantify the rate of increase in available N under the cowpea–sorghum relay intercrop with >75% cattle manure application rates.

Technical efficiency and technology gaps of sorghum plots in Uganda: A gendered stochastic metafrontier analysis

Sorghum plot managers in different locations have varying levels of resource endowment that in turn influence technical efficiency (TE). Therefore, plot managers operate at different levels of technology. The present study applied a stochastic metafrontier approach to assess TE and technology gaps of female, male and jointly-managed sorghum plots. A two limit-Tobit model was subsequently applied to assess determinants of TE. Results indicate that male-managed sorghum plots had the highest metafrontier technical efficiencies (MTEs) (61%, 56% and 15%) and technology gap ratios (TGRs) (98%, 92% and 20%) for Lira, Serere and Kumi districts, respectively compared to female and jointly managed plots. However, jointly managed plots had higher TE and TGRs compared to female plot managers but lower than those of the male-managed plots. Age, distance to plot and farmer group membership influenced TE positively while household size, years of farming sorghum and access to credit had negative effects on efficiency.

Members of the Parasitoid Guild Attacking Natural Enemies of Sugarcane Aphid Melanaphis sacchari Zehntner (Hemiptera: Aphididae), on Sorghum, Sorghum bicolor Moench (L.) (Poaceae), in Southern Tamaulipas, Mexico

Sugarcane aphid, Melanaphis sacchari Zehntner (Hemiptera: Aphididae), causes economic damage to sorghum crops, Sorghum bicolor (L.) Moench (Poaceae), in Mexico where the primary method of control is synthetic insecticides. While there are at least 30 natural enemies associated with M. sacchari, the parasitoids of these natural enemies and their effects on populations are unknown. We conducted a sampling and rearing regime of natural enemies of sugarcane aphid at unmanaged, experimental plots of sorghum in Estación Cuauhtémoc, Altamira, Tamaulipas, Mexico. We identified three wasps parasitizing aphid predators: Diplazon laetatorius Fabricius (Hymenoptera: Ichneumonidae), Homalotylus eytelweinii (Ratzeburg) (Hymenoptera: Encyrtidae), and Homalotylus albitarsus Gahan (Hymenoptera: Encyrtidae). We also identified one hyperparasitoid, Alloxysta sp. Förster (Hymenoptera: Figitidae), which emerged from aphids parasitized by Lysiphlebus testaceipes Cresson (Hymenoptera: Braconidae). We also report the frequency of parasitization.

Impact of buckwheat and methyl salicylate lures on natural enemy abundance for early season management of Melanaphis sacchari (Hemiptera: Aphididae) in sweet sorghum

Early in the growing season when pest densities are low, crop environments are often unattractive to natural enemies. A combination of flowering plants providing food and alternate prey and herbivore induced plant volatiles (HIPV) may attract and retain natural enemies in crops. Melanaphis sacchari Zehntner (Hemiptera: Aphididae), a new pest of sweet sorghum (Sorghum bicolor L.), causes significant yield loss if left unmanaged. In a three-year field study, we tested the extent to which buckwheat (Fagopyrum esculentum Moench) border strips and lures containing the HIPV methyl salicylate attracted natural enemies prior to and during M. sacchari establishment in sweet sorghum plots. Natural enemies were surveyed weekly within the sweet sorghum (visual counts and yellow sticky cards) and in buckwheat border strips outside the plots (vacuum sampling). M. sacchari visual counts and natural enemy surveys were performed until harvest. Within buckwheat border strips, natural enemies were more abundant relative to non-buckwheat border strips. However, the increase in buckwheat borders did not increase natural enemies within sweet sorghum plots. In addition, the most abundant natural enemies within sweet sorghum (Coccinellidae) were uncommon in buckwheat strips. Methyl salicylate did not impact natural enemies in sweet sorghum border strips. M. sacchari populations and sweet sorghum yields were not affected by treatments. Other methods of increasing natural enemies will need to be explored to enhance early season management of M. sacchari in sweet sorghum fields.

Deep Learning Method for Height Estimation of Sorghum in the Field Using LiDAR

Automatic tools for plant phenotyping have received increased interest in recent years due to the need to understand the relationship between plant genotype and phenotype. Building upon our previous work, we present a robust, deep learning method to accurately estimate the height of biomass sorghum throughout the entirety of its growing season. We mount a vertically oriented LiDAR sensor onboard an agricultural robot to obtain 3D point clouds of the crop fields. From each of these 3D point clouds, we generate a height contour and density map corresponding to a single row of plants in the field. We then train a multiview neural network in order to estimate plant height. Our method is capable of accurately estimating height from emergence through canopy closure. We extensively validate our algorithm by performing several ground truthing campaigns on biomass sorghum. We have shown our proposed approach to achieve an absolute height estimation error of 7.47% using ground truth data obtained via conventional breeder methods on 2715 plots of sorghum with varying genetic strains and treatments.

Influence of Rice Husk - Mulch on Soil Water Balance Components under Sorghum and Millet Crops in Maiduguri, Semi Arid Northeast Nigeria

A 2 x 3 factorial experiment was conducted at two sites in Maiduguri, Borno State during the 2009 cropping season. The objective was to evaluate the influence of rice husk-mulch on soil water balance components under sorghum and millet crops. The treatments comprised of two test crops (sorghum and millet) and three rates of application (0, 10 and 15 t ha-1) of rice husk mulch, fitted in a split-plot design. The test crops were assigned to the main plot, while the mulch application rates were assigned to the sub-plot. The treatments were replicated three times. The components of soil water balance determined were annual rainfall, moisture storage within sorghum and millet root zone, drainage below crop root zone and seasonal crop evapotranspiration. Profile moisture content was measured weekly with the aid of a neutron probe installed at a depth of 2.0 m using access tubes. Also, soil (0 – 30 cm depth) moisture content was determined gravimetrically on weekly basis. Rainfall was measured using a manual rain gauge installed at each of the two sites. Findings in this study indicated that, under the prevailing circumstances, annual rainfall was lower than the amount observed over a ten-year period in Maiduguri. Consequently, soil moisture storage, drainage and seasonal crop evapotranspiration generally declined. An average of over 90 % of this low annual rainfall was lost as seasonal crop evapotranspiration. Sorghum plots stored higher moisture within the root zone, had higher drainage and lower seasonal evapotranspiration than millet plots. Moisture storage and drainage increased with increasing mulch application rate, while, seasonal crop evapotranspiration decreased with it.

Soil CO2 emissions measured by closed chamber and soil gradient methods in dry dipterocarp forest and sweet sorghum plots

Soil CO2 emissions measured by closed chamber and soil gradient methods in dry dipterocarp forest and sweet sorghum plots

Dynamics of Sclerotium rolfsii as influenced by different crop rhizosphere and microbial community

This study was carried out with the aim of evaluating pathogenicity of Sclerotium rolfsii to different crops influenced by different crop rhizosphere microbes and their population dynamics. Napier was found to be non-preferred host against S. rolfsii pathogen. Among the seven tested crops in micro-plot study, highest level of induction of sclerotial population was observed in groundnut and cow peas (21.81 and 20.06 numbers of sclerotia /100 g of soil, respectively), whereas, reduction in sclerotial number was observed in napier, maize and sorghum plots. S. rolfsii induced damping off was found to be significantly positively correlated with average sclerotial population irrespective of plant cover even at 1% level of significance (r = 0.985) and among the microbiological parameters, FDA was found to be significantly negatively correlated with damping off disease percentage at 5% level of significance (r = - 0.830). Therefore, Napier may be the potential crop to be incorporated in the sequence of rice/vegetable based cropping system in West Bengal for management of this dreaded pathogen.

Plant characteristics and productivity of sorghum with doses of arbuscular mycorrhiza in Tamaulipas

La inoculación de la semilla de sorgo con el HMA Rhizophagus intraradices (micorriza INIFAP) tiene un impacto positivo en la productividad agrícola en las condiciones áridas y semiáridas del estado de Tamaulipas. Las dosis utilizadas por el productor son heterogéneas, lo que puede traer consigo una práctica ineficiente. El objetivo del trabajo fue evaluar la efectividad y rentabilidad de la producción de sorgo inoculado a diferentes dosis de micorriza INIFAP, comparado con el testigo o el del productor. Tres parcelas experimentales de sorgo (1-2 ha) se establecieron en terrenos de productores de diferentes localidades. La semilla utilizada (7-8 kg∙ha-1) se inoculó con micorriza INIFAP a dosis de 250, 500 y 750 g·ha-1.Las variables índice de clorofila (SPAD), biomasas foliar y radical, longitud de la panoja, rendimiento y costo-beneficio fueron estimadas. Los valores de las variables de planta, rendimiento y rentabilidad de sorgo fueron mayores cuando se inocularon las semillas de sorgo que en los casos testigo. Los resultados indican que la inoculación con micorriza INIFAP en dosis de 500 g∙ha-1 conlleva a maximizar el rendimiento de grano de sorgo y la relación costo-beneficio.

ESTIMATION OF GENETIC PARAMETERS IN SORGHUM UNDER THE EFFECT OF POPULATIONS AND PLANTING SEASONS.

In order to estimate the phenotypic, genotypic and environment variance; and estimate the genotypic and phenotypic coefficient variations; and heritability broad sense. for some traits, in sorghum(Sorghum bicolor L. Moench).Experiment was carried out at the field of Field Crop Dept. College of Agric. Univ. of Baghdad, during Spring and Fall season of 2013, by using split plot arrangement in randomize complete block design with four replications . The population densities are 6000, 7000, 80000 p.ha-1.as the main plots. Traits and variances were recorded on three genotypes of sorghum, Enqath, Rabih and Kaffieras sub plots. Results of statistical analysis showed that the cultivar Enqath the higher yield 5.81 ton.ha-1. and 6.13 ton.ha-1. for Spring and Fall season respectively. This was due to superiority in weight of 1000 grain 32.48g in spring, and no. of grains 2323 grains for Fall. The better population density was 60000 .ha-1. for spring due to highest of grain weight, no. of grains and dry weight for its increase in functional no. of leaves and flag leaf area. In Fall the plant in this population were give higher yield due to superiority in dry weight, leaf area index, grain weight and flag leaf area. The superior cultivar and population characterized in lower leaf area and day to maturity and higher in harvest index. So these traits characterized with higher of genetic variation and heritability.

Kearney and West Side RECs: Studies of sorghum's adaptation to drought push the frontiers of crop improvement

News from the RECs Starting with this issue, California Agriculture will publish a regular feature on projects at UC ANR’s Research and Extension Centers Kearney and West Side RECs: Studies of sorghum’s adaptation to drought push the frontiers of crop improvement W ith the climate changing and demands on water resources growing, crops that can survive drought are near the top of the global agricultural wish list. But drought tolerance has so far confounded plant researchers. One problem is that it involves many complex relationships: a host of genes that activate when a plant is short of water; soil microbes that interact with plant roots. Another difficulty has been that plants respond differently to water stress when they are grown outdoors rather than indoors, meaning that greenhouse-based findings haven’t translated well to the field. Peggy Lemaux Two new research projects involving the Kearney and West Side Research and Extension Centers (RECs) are taking on these challenges, using a mul- tifaceted, field-based approach West Side REC director Bob Hutmacher with sorghum as their subject. collects a soil sample next to a sorghum The knowledge gained could lead plant to evaluate the microbial eventually to the ability to control population around sorghum roots. the mechanisms of drought toler- ance and the development of im- proved varieties of sorghum and other crops. “We may be able to find ways to manipulate those character- istics to enable drought toler- ance and water use efficiency,” said Kearney REC director Jeff Dahlberg. “That’s the ultimate pie-in-the-sky goal.” The projects are funded by recent grants from the U.S. Department of Energy (DOE) — one from the Biological and Environmental Research (BER) Program and the other from the Advanced Research Project Agency-Energy (ARPA-E). The two DOE programs support the study of microbes and plants for sustainable biofuel production. 208 CALIFORNIA AGRICULTURE • VOLUME 69 , NUMBER 4 Sorghum, in addition to being a staple food grain in much of the world, is promising as a bioenergy crop and as a substitute for corn silage in livestock rations. It is a good candidate for improved drought tolerance in part because it already handles water stress better than many other crops, including its close relative, corn. The grain emerged as a food crop in drought- prone areas of Africa, and existing varieties exhibit a range of traits that help the crop endure periods of scarce water. Peggy Lemaux, a UC ANR Cooperative Extension specialist based at UC Berkeley, is the principal in- vestigator on the 5-year, $12.3 million BER-funded project awarded in September. Using field plots of sorghum at Kearney and West Side RECs, the project will investigate what’s known as the epigenetics of drought tolerance — the ways in which certain genes are activated in response to water stress, Lemaux said. These mechanisms, which allow rapid adjustments to stresses, can change the plant’s physiology to better cope with reduced moisture. The project also will investigate how microbes in the soil may interact with sorghum to enhance its drought tolerance. Compounds produced by microbes may act as signals, touching off epigenetic or other responses that help sorghum plants survive a long dry stretch, Lemaux said. Microbial populations also might enhance delivery of water and nutrients to a sorghum plant’s roots and trigger them to produce en- zymes and plant hormones that influence its growth and yield. Lemaux noted that the BER project takes advan- tage of UC ANR’s institutional structure, partnering campus-based Agricultural Experiment Station (AES) faculty and Cooperative Extension specialists with researchers based at the RECs. The project’s collabo- rators also include a UC Berkeley faculty member in statistics and DOE researchers based at the Joint Genome Institute and the Pacific Northwest National Laboratory (PNNL). It’s a powerful combination of laboratory and field expertise and resources, Lemaux said. “We couldn’t do it without them, and they couldn’t do it without us,” Lemaux said of the collaboration be- tween campus- and REC-based researchers.

English

The aim of the experiment was evaluate agronomic characteristics of grain sorghum plots, collected at different sites within four spatial arrangements of eucalyptus for the forest crop livestock integration system (iLPF). The work was implemented in the second crop in the agricultural year 2011-2012, after the soybean harvest in Uberlândia, Minas Gerais. For this, they were planted in areas adjacent seedlings of eucalyptus clone I 144 simple rows: 10 × 2 m; double rows: (2 × 3) + 15 m, (2 × 3) + 20 m in triple rows (3 × 2 × 3) + 20 m. At six months after planting clone, seeded through conventional tillage to cultivate sorghum 1G220 in the eucalyptus rows. It used the experimental randomized block design in split plot with five replications. The plots consisted of four spatial arrangements of eucalyptus and the subplots 3 sorghum assessment of sites within the plots (center, right side and left side of eucalyptus). The site assessment of the plots affectassessment of the plots site affects the main agronomic characteristics of sorghum. In future experiments it is necessary that sorghum portions are formed by central and lateral lines within the wider spacing eucalyptus. The spatial arrangement ( 2 ×x 3 ) + 20 m and 10 ×x 2 m are more promising for the consortium . The definition of best arrangement will depend on the market for the sale of wood. Key words: Agroforestry system, sustainability, consortium.

Effects of treated poultry litter on potential greenhouse gas emission and field agronomic performance

A study was conducted to evaluate the effects of different treatments of poultry faecal waste on potential greenhouse gas emission and inherent agronomic potentials. Sugar solution at 100g/l salt solution at 350g/l and oven-drying were the various faecal treatments examined using a completely randomized design. The experiment was conducted for eight weeks. Salt treatment had significantly lower nitrogen content (1.70%; p 0.05) in microbial count across all treatments, as was observed up till the 8 th week. By the 4 th week oven-dried faeces was lower (p<0.05) in fungal count (0.33×10 3 cfu/ml) compared to other treatments, and completely devoid of Fungi by the end of the 8 th week. On agronomic performance test, maize planted using sugar treatments had a 40% germination percentage (GP) after two weeks, oven-dry treatment and the control had mean GP of 65% and 75% respectively. The Sorghum plot attained 100% GP with the control and oven-dry treatments, sugar treatment recorded 88% GP. In both cases, germination was nil on salt treatment. By the third week ending, maize stands on control treatment were averagely 48cm tall, 19cm on oven-dried treatment and10cm on sugar treated pots. This trend persisted on sorghum plots with oven-dry treatment showing superiority to other treatments, averaging a plant height of 28cm after 21days. Key Words: Sugar, Salt, Oven-drying, Germination, Faecal waste, Fungal count

Fluorescence, PRI and canopy temperature for water stress detection in cereal crops

Narrow-band multispectral remote sensing techniques and thermal imagery were investigated for water stress detection in cereal crops. Visible and near infrared AISA Eagle (Specim, Finland) and thermal AHS-160 (Sensytech Inc., USA) imageries were acquired with an airborne survey on a farm-level experimental site where maize (Zea mays L.) and sorghum (Sorghum bicolor L.) were grown with three different irrigation treatments. Vegetation biophysical and eco-physiological measurements were collected concurrently with the airborne campaign. Leaf fluorescence yield (ΔF/Fm′) resulted to be a good indirect measure of water stress. Therefore, ΔF/Fm′ measurements were compared against remotely sensed indicators: (i) the Photochemical Reflectance Index (PRI), (ii) the sun-induced chlorophyll fluorescence at 760nm (F760), retrieved by the Fraunhofer line depth method and (iii) the canopy temperature (TC) calculated decoupling soil and vegetation contributions. TC was related to ΔF/Fm′ with the highest determination coefficient (R2=0.65), followed by PRI586 (reference band at 586nm) (R2=0.51). The relationship with F760 was significant but weaker (R2=0.36). The coefficient of determination increased up to 0.54 when pigment concentration was considered by multiplying ΔF/Fm′ and chlorophyll content, confirming the close relationship between passive fluorescence signal, pigment content and light photosystem efficiency. PRI586, F760 and TC maps were produced in maize and sorghum plots. The differences in the average values of PRI586, F760 and TC extracted from the plots with different water treatments showed that water treatments were well discriminated in maize plots by the three remotely sensed indicators. This was confirmed by the visual observation of the PRI586, F760 and TC maps, while in sorghum plots, F760 and TC appeared more sensitive to water stress compared to PRI586.

Nitrogen mineralization kinetics and parameter estimates in soil amended with Neem seed cake and inorganic fertilizer in Samaru, Nigeria

A field study was conducted to assess the effect of neem seed cake (NSC) on the kinetics of net nitrogen mineralization and parameter estimates. The experiment consisted of sorghum plots to which milled NSC (with %N > 3) and urea (inorganic N source) were applied. Ammonium-nitrogen and nitrate-nitrogen were determined after 0, 2, 4, 6, 8, 12, 19 and 34 weeks from soils covered with PVC tubes inserted into the sixteen treatment combination plots. Inorganic N concentration in the amended plots and the control were analysed using five mathematical N mineralization models. N0, Ne, h and k were estimated from the fit of each mathematical model. The treatments were highly variable in their respective N mineralization characteristics, but the peaks for mineralized N content were observed at early incubation periods, i. e., 10 -28 days. Potential respective mineralizable N (N0) content of the first order rate, consecutive (h ‚ k), consecutive (h = k), Gompertz and mixed order rate constant was -927E-22, 430.90, 1.9E-21, 568.40 and 427.20 mg kg-1 soil and the respretively rate constant (k) was -5E+21, 0.2269, 2E+23, 0.0954 and 0.8116.respretively Net N mineralization was best described by a mixed order rate model (R2 = 0.992) and residual mean square error (RMSE)was = 28.41. A Gompertz function also fitted the data closely (R2 = 0.999; RMSE = 52.47). The two models recognize that N mineralization is not just a function of substrate N concentration but also of the capacity of the microbial community to adjust to substrate quality and composition affecting their growth and activity. Key words : mineralization model, neem seed cake, N mineralization, parameter estimates, PVC tubes