Grass Growth Research Articles

Differentiating grazing-induced rangeland grass nutrition status in situ using near infrared reflectance

Assessing the nutrient content of rangeland grass using earth observation technologies presents opportunities for non-destructive, rapid and repetitive appraisals in support of rangeland management. The biochemical-related concentrations of macronutrients (N, P, K, Ca, Mg) are among the factors that influence near infrared reflectance (ρNIR) by a turgid leaf. High grazing intensity (GI) enhances nutrient recycling in rangelands, resulting in high concentrations in aboveground grass tissue. This study sought to establish whether grazing-induced macronutrient abundance in rangeland grass can be remotely sensed in situ through ρNIR in the multiple species natural settings. Sampling was conducted at peak grass growth stage in large savannah rangelands with similar grass species mixtures, in low moisture stress conditions. The sampling was widely distributed in GI-contrasted livestock and wild grazer rangelands, and in grazing-restricted control sites. Two species representing high and low nutrient grass species, respectively, were sampled. At each sampling site (N = 116), reflectance was measured in the 350–2500 nm range from leaf and stem tissue of healthy-looking specimens of the two species (≤10 m apart), using a 1.1 nm – 1.4 nm resolution spectroradiometer. Macronutrient concentrations (MNC) in the tissue were then determined in the laboratory. For each species, the hyperspectral NIR (λ700 – 1100 nm) reflectance was averaged per sampling site. Individual and total MNC, respectively, were correlated with the hyperspectral ρNIR, and then with atmospheric effect-corrected ρNIR from 10 m-resolution, field sampling-concurrent Sentinel-2 MSI multispectral images. For each sampling site, the two species’ hyperspectral ρNIR values, individual and total MNC, respectively, were then averaged. Respective models relating the paired hyperspectral ρNIR and averaged MNC were developed, by linear regression and partial least squares regression (PLSR). Tissue MNC were lowest in the control sites and higher in the grazed rangelands. Covariance in MNC in the two species suggested location-context similarities in all grasses. Individual and total MNC, respectively, had statistically significant (p < 0.01) negative correlations with both tissue level hyperspectral and multispectral ρNIR. The negative relationship was detected on empirical line-retrieved ρNIR on historical Hyperion hyperspectral images. PLSR yielded a more accurate predictive model (R2 = 0.760) than linear regression (R2 = 0.601, F = 138.415, p < 0.0001). The study shows that there are possibilities to remotely sense grazing-induced MNC in aboveground grass tissue through changes in ρNIR.

Potential use of coal ash as growing media: Effect on the plant’s growth and future estimation for land reclamation

Coal ash, such as fly ash (FA) and bottom ash (BA) is mostly generated from a Coal-fired Steam Power Generation (PLTU) process. An increase in the number of PLTUs in Indonesia is proportional to the high volume of FA and BA generated, causing adverse environmental impacts if not properly treated. Various studies have highlighted the potential valorization of FA and BA, including building materials, cement ingredients, concrete, and growing media. This study aimed to evaluate the potential use of FA and BA as a growing media and to explore the potential future application for reclamation of heavy-metal-contaminated (or ex-mining) land. The results showed that composting FA with blackwater sludge (BWS) and rice straw (RS) produced compost that complied with the targeted standard. The addition of FA, BA, and composted FA in the growing media impact the growth and Zn adsorption ability of the dwarf elephant grass (Pennisetum purpureum cv. Mott). However, the composted FA has superior performance in general as a growing media. The future estimation of the application FA and BA combined with domestic waste (blackwater and greywater) for reclamation of ex-mining land is proposed. By integrating the phytoremediation ability of the grass plants and the biorefinery approach, the proposed future estimation may provide a sustainable valorization pathway of FA and BA for heavy metal-contaminated or ex-mining land reclamation. Thus, transforming FA and BA as a component of growing media could reduce the potential risk of heavy metals distribution into the food chain and the surrounding environment.

Foliar spray of commercial seaweed and amino acid-derived biostimulants promoted phytoremediation potential and salinity stress tolerance in halophytic grass, Puccinellia distans

Plants pretreatment with various chemicals has often been used to diminish salinity stress impact on plants. An experiment was carried out to determine the effect of foliar spray of two commercially available biostimulants (Algabon® [0.5 g/l] and Bonamid® [2 g/l]) on the growth and tolerance of halophytic grass, Pucccinellia distans under non-salinity condition (NSC) and salinity condition (SC). The greenhouse experiment was set up in a completely randomized design with three treatments repeated three times. Our results showed that biomass, leaf relative water content, chlorophyll content, K+ content, K+/Na+ ratio, and protein and N contents were all negatively affected by 300 mM NaCl. The results obtained in the present study showed the beneficial effects of the pretreatments of two biostimulants on P. distans seedlings under non-salinity stress conditions with respect to increasing plant biomass, photosynthetic pigments, K+ content, the content of proteins, and nitrogen percentage. The results suggested that foliar spray of Bonamid® could partly diminish NaCl-caused stress on P. distans seedlings, probably due to higher accumulation of shoot biomass, photosynthetic pigments, K+/Na+ ratio, protein and N contents, phytoremediation potential, as well as upregulation of Na+/H+ antiporters located in plasma membranes and vacuoles. The highest phytoremediation potential (PP) of shoots and total biomass was detected in the plants sprayed with Bonamid® by 50.8 and 42.7% respectively, relative to that in salinity-stressed control plants. Interestingly, foliar spray with two biostimulants decreased osmoprotectants and antioxidant compounds content of shoots under salinity stress conditions. Collectively, it could be concluded that a noticeable feature of pretreatment of P. distans seedlings with Algabon® and Bonamid® is the increase in growth under NSC, whereas under SC only pretreated plants with amino acid-derived biostimulant (Bonamid®) can (partly) diminish the NaCl-induced deleterious effects in P. distans seedlings through the compartmentalization of salts in vacuoles (by upregulation of Na+/H+ antiporters).

Growth and leaf area analysis of buffel grass subjected to salt stress

Buffel grass has characteristics of resistance and rapid recovery to prolonged drought, however, few studies indicate this resistance to salinity. Thus, the objective was to evaluate the relationship between salt stress and the growth dynamics, green mass production and area of Buffel grass. The experiment was conducted in an entirely randomized design, with three levels of salinity and ten repetitions, totaling 30 experimental units. Measurements of height, cutting and weighing of green mass were made in three periods, with intervals of 28 days between them, and photography of the leaves for analysis in ImageJ software in the last period. The data obtained were submitted to the Shapiro-Wilk normality test and Bartlett's homogeneity test. Kruskal-Wallis non-parametric test and Dunn's post-test was applied for data that did not follow normality, and ANOVA test and Tukey's post-test for those that followed normality and homogeneity. The results indicate that there was no significant difference in height for the treatments with or without salt, so even with the addition of salt there was no interference in growth, but when compared in relation to the periods, it can be observed that the last period was different from the others, this can be explained by the vegetative vigor of the plant, because when it is younger it has more efficient cell multiplication, but as it suffers injuries, the vigor is decreased and growth is slower. Therefore, there are some differences in the behavior of grass submitted to salinity, but they do not significantly interfere in its development.

Effect of Type and Dose of Arbuscular Mycorrhizal Fungi to Growth and Yield of Citronella Grass (Cymbopogon nardus L.) in Former Mining Area Land in Sawahlunto

Aims: The study aimed to determine the type and dose of arbuscular mycorrhizal fungi (AMF) to growth and yield of citronella grass (Cymbopogon nardus L.) in former mining area land in Sawahlunto, West Sumatera, Indonesia.&#x0D; Study Design: Factorial completely randomized design.&#x0D; Place and Duration of Study: The research was conducted in shade net house of Faculty of Agriculture, Andalas University, Padang, West Sumatera, Indonesia from September 2021-January 2022.&#x0D; Methodology: Two factors were used in the study. First factor was types of Arbuscular mychorrhizal fungi (AMF), Glomus sp., Gigapora sp. dan multispores (Glomus sp. + Gigaspora sp.) and the second factor was AMF doses that consisted of four degrees, 5 g, 10 g, 15 g and 20 g/plant. The experiment result was analyzed by using Analysis of variance (ANOVA) in 5% and continued by using Duncan’s New Multople Range Test (DNMRT) in 5%.&#x0D; Results: Type of AMF multispores in 20 g/ plant could number of tiller. Dose 20 g/plant could plant height and number of leaves. AMF multispores only increased number of tiller and net assimilation rate.&#x0D; Conclusion: Type and dose of AMF affected the agronomy parameter of citronella grass in former mining area land.

Characterization of bacterial community and fermentation parameters during ensiling of Napier grasses harvested at various times within a day

Grasses exhibit variations in chemical composition and epiphytic microbiota during daylight. These variations may influence the natural fermentation parameters of silage. This study was to evaluate the bacterial community and fermentation parameters during ensiling of Napier grasses harvested at various times within a day. Secondary growth of Napier grass (vegetative stage) was harvested at 7:00 (AM), 12:00 (M) and 17:00 (PM) on three sunny days. The Napier grasses were ensiled in polyethylene plastic bags and bags were opened after 1, 3, 7, 14, 30 and 60 days. Compared with AM-cut fresh Napier grasses, M and PM-cut fresh Napier grasses had higher (P < 0.05) dry matter, and lower (P < 0.05) crude protein contents and buffering capacity. The lactic acid bacteria (LAB) and aerobic bacteria counts decreased (P < 0.05) with the delay of harvest time. Compared with AM silage, M and PM silages exhibited slower pH declines and WSC consumptions plus less lactic acid production during ensiling. After 7 days of ensiling, propionic acid contents and DM losses tended to be higher (P < 0.05) in M and PM silages compared with AM silage. The M and PM-cut fresh Napier grasses had higher (P < 0.05) bacterial diversity and richness than AM-cut fresh Napier grasses. During ensiling, Lactobacillus gradually dominated the microbiota in AM silage and its relative abundance reached 49.1% at the end of ensiling. By contrast, Klebsiella and Enterobacter tended to flourish in the M and PM silages as ensiling progressed. Analysis of the LAB community showed that M and PM-cut fresh Napier grasses had higher (P < 0.05) relative abundance of Leuconostoc and lower (P < 0.05) Lactococcus compared with AM-cut fresh Napier grasses. On day 3 of ensiling, the relative abundance of Leuconostoc and unclassified_f_Leuconostocaceae were higher (P < 0.05), and Lactococcus and unclassified_o_Lactobacillale were lower (P < 0.05) in M and PM silages as opposed to those in AM silage. After 14 days of ensiling, M and PM silages contained higher Pediococcus and Enterococcus compared with AM silage. These results revealed that Napier grasses harvested at various times within a day had different fermentation parameters and bacterial community during ensiling. In practice, diurnal changes in Napier grass could be an important factor to consider for producing high-quality silage.

Growth Rate and Biomass Accumulation in Forage Maize (Zea mays), Forage Millet (Echinochloa utilis), Elephant Grass (Pennisetum purpureum) and Gamba Grass (Andropogon gayanus)

Background: Understanding the biomass accumulation and growth rate of the forages to feed the animal throughout the year is critical for improved earnings and long-term livestock production. This was found in forage maize (Zea mays), forage millet (Echinochloa utilis), elephant grass (Pennisetum purpureum) and Gamba grass (Andropogon gayanus). The experiment was place at Federal University Oye Ekiti in Ekiti State, Nigeria, in latitude N 07° 48.308, longitude E 005° 29.573 and elevation 548.4 meters above sea level, with an annual rainfall of 1778 mm. Methods: Planting four rows in a complete randomized design (CRD with four replications) was used to test the forage crops. Before planting, the soil in the experimental field had 49.96% organic matter and 33.59% after the crops were harvested. During the growth season, Pennisetum purpereum had the maximum plant height and sward height. Result: The Zea mays plant had the maximum leaf breadth (5.44 cm at 8 weeks) and the most leaves. Zea mays had the largest biomass accumulation (BC) of 113.80% after 8 weeks, followed by Andropogon gayanus with 67.15 per cent, Pennisetum purpureum with 56.24 per cent and Echinochloa utilis with 51.63%. Although there were no significant differences p£0.05 in the crude protein levels of the different species, samples from the latest cuts (8th week) had the greatest crude protein content (11.88% in Andropogon gayanus). Crude protein levels were shown to rise in lockstep with grass growth. Although there was no significant difference between the grass species, the crude fibre content of the three grass species was discovered to vary with the growth phase. The greatest fibre content of 13.58% in Zea mays was reported during the 6th week, which might be attributable to lignin encrustation in grasses that were harvested late. All of the plant samples of crops showed the same irregular pattern in crude fiber, moisture content and fat content, with no significant variance.

Degradation influences equilibrium and non‐equilibrium dynamics in rangelands: implications in resilience and stability

AbstractQuestionPlant communities are structured by both equilibrium and non‐equilibrium dynamics, which interact at different spatiotemporal scales. The influence of external factors on internal regulation processes might depend on ecological state, and thus, on system resilience. We asked if well‐conserved (reference) states have higher resilience to external factors than degraded states, considering the greater capacity for self‐regulation expected of reference states.LocationGraminous–subshrubby steppes of northern Patagonia, Argentina.MethodsDuring four years, we assessed the influence of an external factor (rainfall variability) on internal regulation processes (seedling recruitment, growth of main perennial species, and three resilience proxies) in two alternative states (one reference and another degraded) of graminous–subshrubby steppes of northern Patagonia (Argentina). Specifically, we assessed the response of alternative states to simulated high rainfall events (irrigation).ResultsThe degraded state was more sensitive to rainfall variability than the reference state. Specifically, in the degraded state the density of surviving seedlings, the growth of shrubs and Papostipa speciosa’s relative tiller production and cover increased in response to irrigation; whereas seedling emergence and survival, and grass growth were low or even null without irrigation. Finally, resistance and elasticity were lower whereas malleability was greater in degraded than in reference states.ConclusionsThe degraded state was less resilient (low resistance and elasticity; high malleability) to stochastic weather events (in response to either increases or decreases in water availability. In contrast, the reference state had a great capacity to respond to rainfall variability. However, demographic processes such as seedling recruitment and vegetative growth were compensated by competition and mortality, suggesting a lower sensitivity to external drivers, and thus, a greater stability. By influencing the balance between equilibrium and non‐equilibrium dynamics, degradation might affect the resilience and stability of the ecosystem. Thus, to prevent rangeland degradation, management plans should anticipate climatically favorable and unfavorable periods.

Effects of Aqueous Extracts Obtained from Two Radish Cultivars (Raphanus sativus L. and Raphanus sativus L. var. radikula) Using Liquid Nitrogen Is Germination of Barnyard Grass (Echinochloa crus-galli) and Allelopathic Effect on Seedling Growth

This study was conducted to evaluate the allelopathic effects of extracts obtained from different parts (root, stem and mixed) of radish varieties ( Raphanus sativus L. and Raphanus sativus L. var radicula ) on germination and seedling growth of barnyard grass as well as the identification of the phytotoxic chemicals responsible for allelopathic activity. During the extraction process, the plant parts of the radish varieties were frozen with the help of liquid nitrogen and then, crushed and powdered. Aqueous solutions prepared with certain doses of radish powders (0%, 1%, 2%, 4%, 8%, 16%) were applied to weed seeds. The seeds were kept in an incubator at 25 °C for 15 days. At the end of the period, the germination percentage of the weed seeds was determined by measuring the length of the root and stem. The results indicated that the allelopathic potential of radish on barnyard grass varied depending on the varieties, plant parts and extract concentrations tested. Among the test parameters, the highest allelopathic effects were obtained from the root elongation of barnyard grass. Stem extracts of little radish were the most inhibitory for all test parameters. As a result of GC-MS analysis of little radish stem extract, the presence of many bioactive compounds that may be the source of the allelopathic effect has been revealed. Overall, these results suggest that little radish could be used in bioherbicide development. Keywords: liquid nitrogen, allelopathy, turnip, barnyard grass, germination, elongation, DOI: 10.7176/JBAH/12-14-02 Publication date: July 31 st 2022

Post‐fire recovery of soil microbial functions is promoted by plant growth

AbstractForest fires can alter the biological properties of soils. There is increasing evidence that fires cause a shift in soil microbial communities, which play a central role in forest carbon and nutrient cycling. In this study, we evaluate the effect of soil heating on soil microbial functions. We hypothesised that fire reduces the catabolic functional diversity of soil, and that post‐fire plant growth enhances its recovery. To test this, we experimentally heated a forest soil at 200°C (T200) or 450°C (T450). Heated and unheated soils were then incubated in tubs with or without live grass (Lolium perenne L.). We determined the functional profiles by measuring the substrate‐induced respiration (SIR) using the Microresp™ technique and analysed nutrient availability at the end of the incubation. At both temperatures, soil heating altered the respiration responses to substrate additions and the catabolic functional diversity of soils. Functional diversity was initially reduced in T200 soils but recovered at the end of the incubation. In contrast, T450 soils initially maintained the catabolic functional diversity, but decreased at the end of the incubation. Heating‐induced nutrient availability stimulated the growth of grass, which in turn increased the response to several substrates and increased the functional diversity to values similar to the unheated controls. Our results suggest that fire‐driven alteration of soil microbial communities has consequences at a functional level, and that the recovery of plant communities enhances the recovery of soil microbial functions.Highlights Soil experimental heating altered microbial functions and reduced soil functional diversity. Soil heating also increased nutrient availability, enhancing plant growth. Growth of plants promoted the recovery of soil functional diversity. Post‐fire recovery of functional diversity may be related to the recovery of photosynthetic tissues.

Growth performance evaluation of Bermuda grass (Cynodon dactylon L. Pers. x Cynodon transvaalensis) under different nitrogen application methods and sprigging intensities

Cynodon dactylon (L.) Pers, commonly called Bermuda grass is one among the most commonly used warm season grasses which can withstand drought stress and produce quality turf. Establishing high quality turf is a key management concern. The selection of suitable method of its establishment and precise nutrient management are the first and most important factors for a well-established lawn. N has the greatest impact on grass growth of all the nutrients, and an appropriate N fertiliser can quicken up the development of high-quality mats. Hence a field trial was conducted at Tamil Nadu Agricultural University, Coimbatore to study the growth response of Bermuda grass to 4 different sprigging intensities: S1- 10×10 cm, S2- 15×15 cm, S3- 20×20 cm, S4- 25×25 cm and 3 different methods of N application at fortnight intervals: N1- Granular application at 4g/m2, N2- 2% Foliar spray and N3- IFFCO Nano Urea at 5ml/l of water. Morphological parameters including leaf length, internodal length, shoot length, root length, percent cover and physiological parameters including total chlorophyll content, relative greenness and proline content for drought estimation have been evaluated at 90 days after planting. Plots treated with nano urea showed improved growth response rather plots treated with granular urea. Closer and medium spacing showed quick grass spread compared to wider spacing. Among 12 treatments, Treatment S1N3 (10 X 10 cm spacing with 5 ml/ l of water Nano Urea Foliar Spray) recorded the highest values for almost all the morphological (Leaf length 3.43 cm, Internodal length 3.63 cm, Shoot length 52.46 cm, Root length 11.51 cm and Percent cover 101.25%) and physiological parameters (TCC 3.42 mg/ g fresh wt., Relative greenness 13.86 and Proline content 2.52 mg/ g of fresh wt.). Future thrust can be relied on such encapsulated slow-release N fertilizer to ease out nitrogen loss concern and improved turf quality.

Effectiveness of napropamide herbicide controlling weeds on a golf course in Tropical Indonesia

Weeds existence interferes with the quality, aesthetics, and growth of golf course grass. Napropamide is a herbicide used to control broadleaf and grass weeds. Therefore, field experiments were employed during 2021 at Bandung Giri Gahana Golf Course, Jatinangor District, Sumedang Regency, West Java to determine effects of applying the herbicide in controlling weeds and on the growth of golf course grass. The experiment was laid out in randomized block design was used with six treatments, each of which was replicated four times. The treatments included manual hand weeding, a control, and different doses of Napropamide 50%, namely 6.75, 9, 11.25, and 13.5 kg/ha. The results showed that the herbicide Napropamide 50% with the dose of 6.75 kg/ha until 13.5 kg/ha were effectif to control grass weeds such as Eleusine indica, Panicum repens, Digitaria ciliaris and broad leaves weeds such as Cleome rutidosperma, Amaranthus viridis, Portulaca oleracea, up to 12 weeks after herbicide application without causing toxicity to golf course grass.

Effect Nutrient "N" Dose on Growth and Protein Content of Napier Pakchong Grass and Zanzibar Napier Grass

The purpose of this study was to determine the effect of the dose of nutrient N on the growth and protein content of napier pakchong grass and napier zanzibar grass. The experiment was arranged using a randomized block design (RAK) with a single factor, namely the dose of N fertilizer on two different types of napier grass, including (1) The dose of N fertilizer was 60 kg/ha on the type Napier Pakchong Grass (2) The dose of N fertilizer is 150 kg/ha on the type of Napier Pakchong Grass. (3) The dose of N fertilizer is 240 kg/ha on the type of Napier Pakchong Grass. (4) The dose of N fertilizer is 60 kg/ha on the type of Zanzibar Napier Grass (5) The dose of N fertilizer is 150 kg/ha on the type of Napier Zanzibar Grass (6) The dose of N fertilizer is 240 kg/ha on the type of Napier Zanzibar Grass. The results of this study showed that there was a very significant response to the variable height of the plant throughout the observation period, the observation of the number of tillers and the number of leaves showed a significant response at the age of 14, 28 and 70 days after planting. The stem diameter showed a significant response only at the age of 14 days after planting and also gave a very significant response to the wet weight observation variable but did not give an unsignificant response to the dry weight observation and protein content test.

Efektifitas Triklopir dan Fluroksipir dalam Pengendalian Gulma Berdaun Lebar di Savana Bekol Taman Nasional Baluran

Invasion of broadleved weeds cause competition with local grasses which are the main feed for herbivores. Chemical control should use selective herbicides that only kill the broadleaved weeds without harming the grass. The research was conducted in the savanna Bekol - Baluran National Park, East Java, from January 2015 until March 2015 to find the best rate of herbicide to control broadleaved weeds in the savanna and to estimate the soil residue of herbicide used. The experimental design was a randomized block with six treatments and four replications. The treatments were herbicide applications consisted of (1) the rate of triclopyr at 670 g a.i ha-1 (TA), (2) rate of triclopyr at 1340 a.i ha-1 (TB), (3) the rate of fluroxypyr at 200 g a.i ha-1 (FA), (4) rate of fluroxypir at 400 g a.i ha-1 (FB), (5) Weeding Manual (PM) and (6) Control (K).The result showed that there was a change in the composition of the vegetation after herbicide applied. The dominance of broadleaed weeds was replaced by the dominance of Brachiaria reptans and Sclerechnae punctata. The application of triclopyr at 1340 g ai ha-1 was able to reduce weed infestation to 0.48 g 0.25 m-2 compared to 12.66 g 0.25 m-2 before the herbicide application. It facilitated the growth of grasses up to 6.87 g 0.25 m-2 which was among the best of treatments applied because it has shown maximum effectieness for controlling broadleaved weeds.

Use of Sentinel-2 Derived Vegetation Indices for Estimating fPAR in Olive Groves

Olive tree cultivation is currently a dominant agriculture activity in the Mediterranean basin, where the increasing impact of climate change coupled with the inefficient management of olive groves is negatively affecting olive oil production and quality in some marginal areas. In this context, satellite imagery may help to monitor crop growth under different environmental conditions, thus providing useful information for optimizing olive grove management and final production. However, the spatial resolution of freely-available satellite products is not yet adequate to estimate plant biophysical parameters in complex agroecosystems such as olive groves, where both olive trees and grass cover contribute to the vegetation indices (VIs) signal at pixel scale. The aim of this study is therefore to test a disentangling procedure to partition the VIs signal among the different components of the agroecosystem to use this information for the monitoring of olive growth processes during the season. Specifically, five VIs (GEMI, MCARI2, NDVI, OSAVI, MCARI2/OSAVI) as recorded by Sentinel-2 at a spatial resolution of 10 m over five olive groves in the Montalbano area (Tuscany, Central Italy), were tested as a proxy for olive tree intercepted radiation. The olive tree volume per pixel was initially used to linearly rescale the VIs signal into the relevant value for the grass cover and olive trees. The models, describing the relationship between rescaled VIs and observed fraction of Photosynthetically Active Radiation (fPAR), were fitted and then validated against independent datasets. While in the calibration phase, a greater robustness at predicting fPAR was obtained using NDVI (r = 0.96 and RRMSE = 9.86), the validation results demonstrating that GEMI and MCARI2/OSAVI provided the highest performances (GEMI: r = 0.89 and RRMSE = 21.71; MCARI2/OSAVI: r = 0.87 and RRMSE = 25.50), in contrast to MCARI2 that provided the lowest (r = 0.67 and RRMSE = 36.78). These results may be related to the VIs’ intrinsic features (e.g., lower sensitivity to atmosphere and background effects), which make some of these indices, compared to others, less sensitive to saturation effects by improving fPAR estimation (e.g., GEMI vs. NDVI). On this basis, this study evidenced the need to improve the current methodologies to reduce inter-row effects and select appropriate VIs for fPAR estimation, especially in complex agroecosystems where inter-row grass growth may affect remote sensed-derived VIs signal at an inadequate pixel resolution.

Effects of Sewage Sludge Application on Plant Growth and Soil Characteristics at a Pinus sylvestris var. mongolica Plantation in Horqin Sandy Land

The application of domestic sewage sludge (SS) may affect plant growth and soil quality through altering nutrient availability. However, the effect of SS application on the plant–soil system in sandy soils is poorly understood. In this study, we established SS application treatment plots (SL, 25 t ha−1) and control treatment plots without sewage sludge application (CK, 0 t ha−1). SS was applied to the soil surface of a Mongolian pine (Pinus sylvestris var. mongolica) plantation in Horqin Sandy Land, Inner Mongolia, China, to assess its potential effects on plants and soil. We analyzed tree growth performances (tree height, basal diameter, and diameter at breast height), understory traits (species diversity, coverage, and aboveground biomass), soil physical and chemical parameters (nutrient content, dissolved organic carbon, soil water content, bulk density, pH), and proxies of ecosystem services (soil organic carbon and total nitrogen stocks). The results showed that SS addition not only significantly increased soil nutrient contents, but also markedly enhanced aboveground productivity and plant coverage. Specifically, SS addition decreased soil bulk density and increased concentrations of soil organic carbon, total nitrogen, and total phosphorus and mineral nitrogen, and it also increased soil carbon and nitrogen stocks. Furthermore, the addition of SS significantly increased soil dissolved organic carbon contents and enhanced the fluorescence intensities of dissolved organic carbon components (humic acid-like and UV fulvic acid-like) in the topsoil (0–5 cm). This study provides evidence that SS is an acceptable, and possibly preferred organic fertilizer for improving the soil quality and tree–grass growth of Mongolian pine plantations.

Growth and biochemical responses of vetiver grass (Vetiveria zizanioides) to magnetized water and Pb

An experiment was conducted to evaluate the phytoremediation efficiency, growth and biochemical responses of vetiver grass (Vetiveria Zizanioides) in response to irrigation with magnetized water [in 3 levels including magnetized water, semi-magnetized water and non-magnetized water] and Pb from the source of Pb-Nitrate salt [in 4 levels including 0, 5, 10 and 20 mg/L). This study was carried out as a factorial arrangement based on a completely randomized design with three replications in the central nursery of Green Area and Parks Organization Bandar Abbas Municipality, Bandar Abbas, Iran, during 2020–21. A magnetic water generating device called a magnetic ion stirrer with an intensity of 110 Tesla was used in this study. The results showed that irrigation with the magnetized water significantly increased the growth and yield of vetiver, and uptake and translocation factor of Pb to the shoots. Increase in the activities of enzymatic antioxidants affected by the magnetized water was observed which led to the production of reactive oxygen species (ROS) and activated the plant defense system. In general, despite high accumulation of Pb in plant tissues evident from accumulation of ROS, but still vetiver growth and yield were not significantly affected, indicating the phyto-toxic tolerance of vetivar against Pb accumulation. It is concluded that irrigation with the magnetized water through stimulating the antioxidants of vetiver can improve the growth, yield, uptake and translocation of Pb and therewith increases the phytoremediation efficiency of Vetiver.

Estimating the impact of climate change on the carbon exchange of a temperate meadow steppe in China

Temperate meadow steppe is a representative ecosystem in northeast China. A process-oriented biogeochemistry model, denitrification–decomposition (DNDC) biogeochemistry model was employed and adapted to interpret and integrate field observations to determine whether temperate meadow steppe ecosystem was a carbon dioxide (CO2) sink during the growing seasons from 2010 to 2011. Then, we applied the model to predict the long-term impacts of climate change on the carbon dynamics in the ecosystem. Daily weather data for 2010–2011 in conjunction with the soil properties data and management practices data for this site were utilized as inputs to simulate the grass growth and soil carbon dynamics. The modeled carbon fluxes were compared with eddy tower data. The observed and modeled CO2 fluxes data were consistent, with both showing that the temperate meadow steppe is a stable carbon sink. Prediction tests were conducted with a baseline and eight alternative climate scenarios for the period 2017–2050. Simulations for the years 2017–2050 found that (1) the temperate meadow steppe will be a carbon sink under the baseline climate conditions; (2) the decelerated warming and drier climate scenario produced the lowest grass production and lowest carbon sequestration; and (3) the accelerated warming and wetter climate scenario produced the highest biomass and highest carbon sequestration. By using DNDC model we can understand carbon dynamics in temperate meadow steppe. The ecosystem production is limited by precipitation, a wetter future climate would substantially elevate the carbon sequestration capacity of the ecosystem. However, the carbon sequestration potential could significantly decrease if the climate is more arid from 2017 to 2050.

Application of Organic Fertilizer Changes the Rhizosphere Microbial Communities of a Gramineous Grass on Qinghai-Tibet Plateau.

The effects of organic fertilizer application on the soil microbial community in grassland systems have been extensively studied. However, the effects of organic fertilizers on the structure of rhizosphere microbial communities are still limited. In this study, the diversity and composition of rhizosphere microbial communities of a gramineous grass Elymus nutans under organic fertilizer treatment were studied in an artificial pasture on Qinghai–Tibet Plateau. After a growing season, the application of organic fertilizer not only increased the height and biomass of Elymus nutans, but also changed the rhizosphere microbial compositions. In particular, organic fertilizer increased the diversity of rhizosphere bacterial community and inhibited the growth of pathogenic bacteria such as Acinetobacter, but the opposite trend was observed for the diversity of fungal community. The assembly process of fungal community was changed from a stochastic process to a deterministic process, indicating that selection was strengthened. Additionally, both the infection rate of arbuscular mycorrhizal fungi (AMF) toward host plants and the development of AMF-related structures were significantly increased after the application of organic fertilizer. Our study demonstrated that the addition of organic fertilizer to artificial pasture could improve the growth of grass through the alteration of the rhizosphere microbial communities. Organic fertilizer had a greater selectivity for the bacterial and the fungal communities that enhanced the niche filtration in this community, further benefiting the yield of forages.

Modelling the effects of stocking rate, soil type, agroclimate location and nitrogen input on the grass DM yield and forage self-sufficiency of Irish grass-based dairy production systems

AbstractIn pasture-based dairy production systems, identifying the appropriate stocking rate (SR; cows/ha) based on the farm grass growth is a key strategic decision for driving the overall farm business. This paper investigates a number of scenarios examining the effects of SR (2–3 cows/ha (0.25 unit changes)), annual nitrogen (N) fertilizer application rates (0–300 kg N/ha (50 kg/ha unit changes)), soil type (heavy and a free-draining soil) and agroclimate location ((south and northeast of Ireland) across 16 years) on pasture growth and forage self-sufficiency using the pasture-based herd dynamic milk model merged with the Moorepark St Gilles grass growth model. The modelled outputs were grass growth, grass dry matter intake, silage harvested and offered, overall farm forage self-sufficiency and N surplus. The model outputs calculated that annual grass yield increased from 9436 kg DM/ha/year when 0 kg N/ha/year was applied to 14 996 kg DM/ha/year when 300 kg N/ha/year were applied, with an average N response of 18.4 kg DM/kg N applied (range of 9.9–27.7 kg DM/kg N applied). Systems stocked at 2.5 cows/ha and applying 250–300 kg N fertilizer/ha/year were self-sufficient for forage. As N input was reduced from 250 kg N/ha/year, farm forage self-sufficiency declined, as did farm N surplus. The results showed that a reduction in N fertilizer application of 50 kg/ha/year will require a reduction in an SR of 0.18 cows/ha to maintain self-sufficiency (R2 = 0.90).