Nutrient-use Efficiency Research Articles

An Innovative Corn to Silage-Grass-Legume Intercropping System With Oversown Black Oat and Soybean to Silage in Succession for the Improvement of Nutrient Cycling

In the context of sustainable tropical agriculture, an innovative corn (Zea maysL.) to silage-grass-legume intercropping system can promotes plant diversity, improves agronomic performance and land-use efficiency, and increases the yield of oversown black oat (Avena strigosaSchreb) and soybean [Glycine max(L.) Merr.] to silage in succession. Thus, during three growing seasons on a Typic Haplorthox in Botucatu, São Paulo State, Brazil, four treatments of a corn to silage production system were implemented in summer/autumn with black oat oversown in winter/spring: (1) corn intercropped with palisade grass (Urochloa brizantha“Marandu”) and black oat overseeded in lines; (2) corn intercropped with palisade grass and black oat overseeded in a broadcast system with superficial incorporation; (3) corn intercropped with palisade grass + pigeon pea [Cajanus cajan(L.) Millsp.] and black oat overseeded in lines; and (4) corn intercropped with palisade grass + pigeon pea and black oat overseeded in a broadcast system with superficial incorporation. During winter/spring, the black oat pastures were grazed by lambs, but results on forage allowance and nutritive value for animal grazing and on animal performance are not reported in the present manuscript. In the fourth growing season, the effect of soybean to silage intercropped with guinea grass (Panicum maximum“Aruana”), with only a residual effect of the four production systems from the previous three growing seasons, was evaluated. Despite greater interspecific competition of palisade grass and pigeon pea intercropped with corn, this more complex system produced better results. Thus, when analyzing this system as a whole, the triple intercrop (corn + pigeon pea + palisade grass) combined with oversown black oat in lines was the most effective option for silage production and for the improvement of other elements of system productivity, such higher surface mulch quantity, leaf nutrient concentrations, and yield of soybean to silage intercropped with guinea grass. This intercrop also generated better nutrient cycling because an increased quantity of nutrients was retained in standing plant residue and surface mulch, which resulted in better land- and nutrient-use efficiency, with an emphasis on nitrogen and potassium.

Effect of seed source, light, and nitrogen levels on biomass and nutrient allocation pattern in seedlings of Pongamia pinnata.

Nitrogen (N) and light are critical determinants of plant growth and productivity. The present study attempts to quantify the underlying mechanisms and effects of light, N levels, and seed source on growth, biomass, nutrient allocations, and nutrient use efficiencies (NUEs) in seedlings of Pongamia pinnata. The differential and fixed hypothesis and isometric and allometric relationships were also examined. Six morphologically superior seed sources of P. pinnata from three contrasting agro-climatic conditions of India were evaluated with application of two levels of both N (low dose @ 5g plant-1 and 15 g plant-1) and light regimes (full light-100% and low light-50%) in mother nursery. Among the seed sources, the native Raipur seed source was found outstanding in growth, biomass, and nutrient use efficiency. N was more critical than light in promoting growth in seedlings of P. pinnata. High N and high light regimes increased shoot/root ratios. The components showed allometric growth and followed a differential allocation pattern. The exploitation of suitable genetic resources combined with managerial interventions is necessary for development of quality planting stock of P. pinnata. Nutrient use efficiencies, biomass production, and their allocation were important indicators and criteria for selection. The study suggests that Raipur and Jabalpur seed sources having high NUE should be grown along with adequate N application (15 g plant-1) and light conditions.

Fertilizer responsiveness of high-yielding drought-tolerant rice in rainfed lowlands

ABSTRACT Recent advances in rice breeding in tropical Asia led to the release of high-yielding drought-tolerant cultivars. Together with the use of these cultivars, improved nutrient management under drought should further increase rice productivity in rainfed lowland ecosystems. The objectives of this study were to evaluate cultivar differences in the responses of plant growth and grain yield to fertilizer application regimes. We compared 13 drought-tolerant rice cultivars with two irrigated rice cultivars under three nutrient management conditions in irrigated and rainfed lowlands in the Philippines during the wet seasons of 2014 and 2015. Drought stress was mild in both years, with a yield reduction of 11 to 12%, and there was no significant cultivar × nutrient management interaction in yield. The drought-tolerant cultivar NSIC Rc282 proved fertilizer-responsive, and had similar yield to those of the popular high-yielding cultivar NSIC Rc222 under all conditions. An ancillary experiment in 2016 confirmed that NSIC Rc282 was more drought-adapted than NSIC Rc222, with 11% to 37% higher yield under stress. In order to maximize the yield, NSIC Rc282 required N application only when the drought ended, whereas NSIC Rc222 required additional N during the drought. This shows that the details of drought-adaptive nutrient management differ between irrigated and drought-tolerant rice cultivars. We suggest that the introduction of high-yielding drought-tolerant rice cultivars will both improve productivity and increase the nutrient-use efficiency in rainfed environments.

Nutrient uptake and nutrient use efficiency of cassava genotypes with different starch bulking periods as affected by different planting dates

Information on macronutrient uptake and nutrient use efficiency (NUE) of cassava genotypes under different planting dates is limited. The aims of this study were 1) to investigate the responses of cassava genotypes to planting dates for nutrient uptake and NUE and 2) to identify the superior genotypes based on these traits. Three cassava genotypes (Kasetsart 50 (KU50), Rayong 11 (RY11) and CMR38-125-77) were planted in a randomized complete block design with four replications at four planting dates (20-Apr, 30-Jun, 5-Oct and 15-Dec 2016) and harvested at 12 months after planting (MAP). Planting cassava on 20-Apr and 15-Dec produced the highest total crop nutrient uptake and nutrient uptake for storage roots. Whereas planting cassava on 5-Oct and 15-Dec with higher solar radiation, temperature, relative humidity and longer photoperiod during canopy establishment until high carbohydrates translocation and with lower temperature and shorter photoperiod during a dormancy period resulted in greater NUE for biomass and storage roots and nutrient harvest index for all genotypes and most elements. CMR38-125-77 and KU50 showed good performance in terms of total nutrient uptake across planting dates (1.45–38.31 g plant−1) for most elements. CMR38-125-77 seems to be the best genotype on the basis of high storage root dry weight, high NUE for both biomass (90.1–1,594.6) and storage roots (39.9–927.1) and nutrient harvest index (0.14–0.58) for almost all planting dates, except in planting date 20-Apr in which RY11 was the highest for these traits. The genotype identified is useful as parental source for further breeding programs to improve genotypes with high NUE and high storage root yield.

Legume-oilseed intercropping in mechanised broadacre agriculture – a review

Intercropping aims to exploit complementary and facilitative interactions between species to improve capture and efficiency in the use of resources, and yield and profit per unit land and time. This review uses the ecological theory of intercropping to investigate the agronomic benefits and drawbacks of legume-oilseed intercropping and its place in mechanised broadacre agriculture. Complementary, competitive and facilitative interactions between species are analysed with a focus on nutrients and water in a range of legume oilseed pairings including pea-canola, soybean-sunflower, and chickpea-flax. Of the 41 studies investigated, 35 report yield, nutrient-use efficiency, or economic benefits of legume-oilseed intercropping. Legume-oilseed intercrops appear to negate many of the agronomic and technical issues associated with the more traditional cereal-legume pairings, and offer novel benefits such as the break-crop advantage to cereal dominant systems, and allelopathic pest repellence. While many of the traditional constraints to manage intercrops in broadacre mechanised systems appear to be tractable, this review also identifies priorities for further research and development of legume-oilseed intercrops. We conclude that legume-oilseed species pairings may have potential as commercially viable, large scale intercrops, as an effective means to improve productivity in broadacre mechanised agricultural systems.

Valorization of cherry pits: Great Lakes agro-industrial waste to mediate Great Lakes water quality.

To meet human food and fiber needs in an environmentally and economically sustainable way, we must improve the efficiency of waste, water, and nutrient use by converting vast quantities of agricultural and food waste to renewable bioproducts. This work converts waste cherry pits, an abundant food waste in the Great Lakes region, to biochars and activated biochars via slow pyrolysis. Biochars produced have surface areas between 206 and 274m2/g and increased bioavailability of Fe, K, Mg, Mn, and P. The biochars can be implemented as soil amendments to reduce nutrient run-off and serve as a valuable carbon sink (biochars contain 74-79% carbon), potentially mitigating harmful algal blooms in the Great Lakes. CO2-activated biochars have surface areas of up to 629m2/g and exhibit selective metal adsorption for the removal of metals from simulated contaminated drinking water, an environmental problem plaguing this region. Through sustainable waste-to-byproduct valorization we convert this waste food biomass into biochar for use as a soil amendment and into activated biochars to remove metals from drinking water, thus alleviating economic issues associated with cherry pit waste handling and reducing the environmental impact of the cherry processing industry.

Recent Achievements and New Research Opportunities for Optimizing Macronutrient Availability, Acquisition, and Distribution for Perennial Fruit Crops

Tree responses to fertilizer management are complex and are influenced by the interactions between the environment, other organisms, and the combined genetics of composite trees. Increased consumer awareness of the environmental impact of agriculture has stimulated research toward increasing nutrient-use efficiency, improving environmental sustainability, and maximizing quality. Here, we highlight recent advancements and identify knowledge gaps in nutrient dynamics across the soil–rhizosphere–tree continuum for fruit crops. Beneficial soil management practices can enhance nutrient uptake and there has been significant progress in the understanding of how roots, microorganisms, and soil interact to enhance nutrient acquisition in the rhizosphere. Characterizing root architecture, in situ, still remains one of the greatest research challenges in perennial fruit research. However, the last decade has advanced the characterization of root nutrient uptake and transport in plants but studies in tree fruit crops have been limited. Calcium, and its balance relative to other macronutrients, has been a primary focus for mineral nutrient research because of its important contributions to the development of physiological disorders. However, annual elemental redistribution makes these interactions complex. The development of new approaches for measuring nutrient movement in soil and plant systems will be critical for achieving sustainable production of high-quality fruit in the future.

Agroforestry- A sustainable Tool for Climate Change Adaptation and Mitigation

According to WMO (World Meteorological Organization), 2018 was the fourth warmest year on record and average global temperature reached approximately 1°C above pre-industrial level portraying climate change. Changing weather had an impact on lives and sustainable development especially in developing countries. Agriculture is the human enterprise that is most vulnerable to climate change. Large percentage of the population of developing countries depends upon agriculture for their livelihoods. Agroforestry, is an age old management system practiced by farmers to provide shade, a steady supply of food throughout the year, arrest degradation and maintain soil fertility, diversify, increase and stabilize income sources, enhance use efficiency of soil nutrients, water and radiation and provide regular employment thereby increasing system resilience. Agroforestry, thus provides an example of a set of innovative practices designed to enhance productivity in a way that often contributes to climate change mitigation and can also strengthen system’s ability to cope with adverse impacts of changing climate conditions.

Differential determinants of growth rates in subtropical evergreen and deciduous juvenile trees: carbon gain, hydraulics and nutrient-use efficiencies.

Growth rate varies across plant species and represents an important ecological strategy for competition, resource-use and fitness. However, empirical studies often show a low predictability of functional traits to tree growth. We measured stem diameter and height growth rates (DGRs and HGRs) of 96 juvenile trees (2-5m tall) of eight evergreen and eight deciduous broadleaf tree species over three consecutive years in a subtropical forest in south-western China. We examined the relationships between tree growth rates and 20 leaf/stem traits that are associated with carbon gain, stem hydraulics and nutrient-use efficiency, as well as the difference between evergreen and deciduous trees. We found that cross-species variations of stem DGR/HGR can be predicted by leaf photosynthetic capacity, leaf mass per area, xylem-theoretical-specific hydraulic conductivity, wood density (WD) and photosynthetic-nutrient-use efficiencies. Higher leaf carbon assimilation and lower leaf/stem constructing costs facilitate deciduous species to be more resource acquisitive and consequently faster growth within a relatively shorter growing season, whereas evergreen species exhibit more conservative strategies and thus slower growth. Furthermore, stem growth rates of evergreen species showed were more dependence on leaf carbon gains, whereas stem hydraulic efficiency was more important for deciduous tree growth. Our results suggest that physiological traits (photosynthesis, hydraulics and nutrient-use efficiency) can predict tree diameter and height growth of subtropical tree species. The differential resource acquisition and use strategies and their associations with tree growth between evergreen and deciduous trees provide insights into explaining the coexistence of evergreen and deciduous tree species in subtropical forests.

Study of a fodder protein supplement from plant raw materials with phytobiotic properties

The Russian market is oversaturated with grain raw materials in the composition of mixed fodders, which are characterized by a protein deficiency and poor digestibility of nutrients. One of the problems of modern animal husbandry is to increase productivity, and most importantly, to reduce the cost of production due to the efficient use of feed nutrients. Phytobiotics have antiviral, antimicrobial, and immunomodulating effects. Feed consumption is increased and the acid-base environment is normalized when they are included in any diet. Phytobiotics are safe for farm animals and birds. Studies of the amino acid composition and antioxidant activity of the protein feed additive obtained from the leafy mass of red clover plants were carried out in the work. The qualitative and quantitative composition of amino acids and the value of antioxidant activity prove the advisability of introducing a fodder protein supplement into the diet of feeding farm animals and birds. The main advantage of feeding a plant-based supplement is that farm animals and poultry are not exposed to any risks, as well as the possibility of its use as a flavoring and an appetite stimulant. It is assumed that the application of an additive from the vegetative mass of red clover will stimulate growth, reproduction, weight gain and will have antibacterial and immunostimulating effects.

Microbial Consortia for Sustaining Productivity of Non-legume Crops: Prospects and Challenges

Soil micro-organisms play a pivotal role in food production through their significant effects on nutrient transformation and release, soil organic matter and carbon dynamics, and biotic and abiotic stress tolerance to plants. The microbial consortia (MC) are mixtures of two or more microbial species/strains, living together symbiotically. Generally, a consortium of micro-organisms performs better than the inoculum of single microbial species. The MC, specifically plant growth-promoting rhizobacteria and biofilm biofertilizers can be used in non-legume cereal crops grown in a large area of the world. The MC may help in solubilization of plant nutrients from the soil native pool, production of beneficial substances (siderophores, hormones, etc.) for better root growth of non-legume crops and reduction in plant growth retarding hormone(s). The MC research focuses/encompasses, mainly legume crops, although there are prospect and substantial evidences of their use in non-legume crops. Reports indicate that the use of MC can enhance micronutrients, total organic carbon and N in soil. They could fix N, solubilize P and K, improve soil physico-chemical properties and act as phyto-stimulator. Globally, almost 50% of the total N, P and K used in crops are consumed by cereal crops, which are heavy feeder with high yield potential. Integration of MC with chemical fertilizers provides enormous scope for increasing nutrient-use efficiency in accordance with harmonious improvement in crop yield and soil health. The MC as a component of integrated nutrient management in non-legume cereal crops would considerably reduce the demand and use of mineral fertilizers and cost of cultivation and save nutrient for use in other crops of economic importance. They are low-cost and eco-friendly options and can improve soil health vis-a-vis enhancing productivity of non-legume crops.

Water stress and warming impact nutrient use efficiency of Mombasa grass (Megathyrsus maximus) in tropical conditions

AbstractTemperature and other abiotic factors, such water and nutrient availability, play an important role for plants in response to the changing environments. At this regard, both warming and drought might affect the nutrient use efficiency (NUE) and growth ofMegathyrsus maximusa C4 forage grass of high interest for cattle feeding. However, the nutrient requirements of this species under climate change are unknown. Therefore, we aimed to evaluate the individual and combined effects of two levels of temperature: ambient and elevated temperature (2°C above ambient temperature), and two levels of soil water availability: irrigated plants and non‐irrigated plants on accumulation of leaf nutrients, NUE and biomass production ofM. maximus. Temperature control was performed by a temperature free‐air‐controlled enhancement (T‐FACE) system under field conditions. In general, we observed that warming under well‐irrigated conditions increased the leaf accumulation of most nutrients, improving the NUE of N, P, K, Ca, Mg, Cu, Mn and Zn. Plant growth was also enhanced under warming effects, with higher leaf dry mass accumulation and root development. Meanwhile, drought decreased NUE of K, Ca, B and leaf dry biomass, while root growth was stimulated. The combined effects of warming and drought on nutrient accumulation, NUE and plant growth tended to be greater than the individual effects expected from a single factor; thus, warming mitigated the negative impacts of individual drought. In summary, our findings suggest that warming and drought, both as individual and combined factors, will change the nutrient requirements ofM. maximusin tropical ecosystems.

Light Intensity Effects on the Growth, Physiological and Nutritional Parameters of Tropical Perennial Legume Cover Crops

In the early stages of the establishment of plantation crops such as cacao, perennial legume cover crops provide vegetative cover to reduce soil and nutrient loss by erosion. Light intensity at cover crop canopy levels greatly influences their adaptability and optimum growth. As tree crops mature, understory cover crops suffer from inadequate light intensity. A greenhouse experiment was undertaken with nine perennial legume cover crop species (Calopo, Ea-Ea, Jack Bean, Lab-Lab, Mucuna ana, Mucuna preta, Cowpea, Black Pigeon Pea and Mixed Pigeon Pea) to assess the effects of three photosynthetic photon flux densities (PPFDs, µmol m−2 s−1) 180 (inadequate light), 450 (moderate light) and 900 (adequate light) on growth, physiological and nutrient uptake parameters. PPFD had highly significant effects on leaf, shoot and root growth parameters and increasing the light intensity from 180 to 900 µmol m−2 s−1 increased all growth parameters with the exception of specific leaf area. In all the legume cover crops, increasing the light intensity significantly increased the net assimilation rates (NAR), SPAD index and net photosynthesis (PN) and its components, stomatal conductance (gs), transpiration (E) and vapor pressure deficit (VPD). Cover crop species, PPFD and their interactions significantly affected water flux (Vo) and various water use efficiency parameters (WUETOTAL, WUEINST and WUEINTR). Increasing the PPFD increased the WUE in all of the cover crops. Species and PPFD had highly significant effects on the uptake of macro- and micronutrients. Overall uptakes of all nutrients were increased with increases in the PPFD from 180 to 900 µmol m−2 s−1. With few exceptions, the nutrient use efficiency (NUE) of the nutrients was significantly influenced by species, PPFD and their interactions. Except for Mn, increasing the PPFD from 180 to 900 µmol m−2 s −1 increased the NUE for all the nutrients.

Assessment of climatic variability on optimal N in long-term rice cropping system

Climatic variability is one of the most significant factors influencing year-to-year crop production, even in high yielding and high-technology agricultural areas. Many studies have attributed variation in yield and crop response to N fertilizer in general terms to differences in varietal characteristics, but few attempts have been made to systematically disentangle the contributions of the genotype from other factors as climatic conditions. In this study, we used ORYZA V3 rice crop model to evaluate impact of climatic variability on optimum nitrogen application rate in rice cropping system. The results show that, solar radiation and N management practices play important roles in the response of N in grain yield. Maximum and minimum temperature has less effect on the grain yield compared to the solar radiation. Optimum N was higher in the dry season compared with the early wet season. Optimum N rate for the grain yield was around 200, 150 and 100. Nutrient use efficiency (NUE) was higher in early wet season (EWS) and late set season (LWS) in higher rate of nitrogen compared to the dry season (DS). Observed grain yield and simulated grain yield was almost similar in both seasons. The ORYZA simulation model performs well for estimating optimum N application.

Simultaneous Optimization of Water Usage Efficiency and Yield of Cucumber Planted in a Columnar Aeroponic System

The development of aeroponic cultivation technology has led to more efficient use of water and plant nutrients for producing high quality agricultural commodities. In this research, cucumbers were grown in columnar aeroponic systems for nine weeks and the effect of spraying rate and spraying duration on the cucumber average yield and water usage efficiency were investigated. The experiments were performed using factorial experiment based on completely randomized designs. The spraying rate had three levels of 125, 250 and 375 mL/min, and the spraying durations were 10, 15 and 20 min. During the experiment, the spraying pumps were turned off for 15 min between each spraying time. Then, the two factors were simultaneously optimized using response surface methodology to maximize fruit yield and water usage efficiency. The ANOVA results showed that both responses were significantly affected by the main effects of the factors (α = 0.01) and by their interaction effects (α = 0.05). The comparison of first and second-order models to show the average yield and water usage efficiency as functions of sparing rate and sparing time indicated that the second-order models fitted with higher accuracies (R2> 80%) to the experimental data than the first-order model. Simultaneous optimization showed that the most suitable spraying rate was 233.37 mL/min and for the spraying duration, it was 16.06 min. At the optimum conditions, the average yield per plant yield was 2.96 kg and the water usage efficiency was 110.37 kg/m3.

MACRONUTRIENT RATES AND MULTIFUNCTIONAL MICROORGANISMS IN A TROPICAL FLOODED RICE CROP

ABSTRACT Tropical flooded rice production systems require a high input of fertilizers and chemical defensive. The use of plant growth-promoting rhizobacteria (PGPR), a sustainable component of this system, can increase nutrient-use efficiency and lead to significant increases in the grain yield of tropical flooded rice crop. This study aimed to determine the effect of the microorganism BRM 32110 (Bacillus thuringiensis) in combination with nitrogen (N), phosphorus (P) and potassium (K) application rates on the physiological and agronomic performance of tropical flooded rice plants. Trials were performed in the 2016/2017 growing season in Formoso do Araguaia, a city in Tocantins state, Brazil. Three independent experiments (E1, E2, and E3) were performed in a randomized block design in a 4 x 2 factorial scheme with three replications. E1 comprised four N application rates (0, 40, 80 and 120 kg N ha-1) with and without the addition of BRM 32110, E2 comprised four P2O5 application rates (0, 40, 80 and 120 kg P2O5 ha-1) with or without BRM 32110, and E3 comprised four K2O application rates (0, 20, 40 and 60 kg K2O ha-1) with and without BRM 32110. In fertile soil, there were no interactions between the rhizobacterium BRM 32110 and the N, P or K application rates. BRM 32110 improved nutrient uptake and, on average, increased shoot dry matter by 8%, photosynthesis rate by 14% and grain yield by 11% in the flooded rice plants. Our results suggest that the use of multifunctional microorganisms is a good strategy for improving flooded rice grain yield sustainably.

Biomass:N:K:Ca:Mg:P ratios in forest stands world‐wide: Biogeographical variations and environmental controls

AbstractAimCommunity‐level biomass‐to‐nutrient ratios and elemental stoichiometry of forests can provide insights for understanding the efficiency of nutrient use and the adaptation strategies of trees. However, the global‐scale pattern of biomass:N:K:Ca:Mg:P ratios in forest stands and its responses to environmental drivers remain unknown.LocationWorld‐wide.Time period1959–2015.Major taxa studiedTrees in forests.MethodsWe synthesized data from 356 forests distributed globally to study the biogeographical variations in biomass‐to‐nutrient ratios and elemental stoichiometry.ResultsOur results revealed that the biomass:N, biomass:P, biomass:K, biomass:Ca and biomass:Mg ratios of living trees in forests averaged 330.2 ± 11.1, 3847.1 ± 164.6, 615.3 ± 26.1, 393.2 ± 15.0 and 2221.5 ± 92.0, respectively. The biomass:N, biomass:K, biomass:Mg, P:K, P:Mg and Ca:Mg ratios decreased with mean annual temperature and increased from low to high latitude, whereas the N:P and K:Ca ratios displayed the opposite trends. The biomass:P, N:P and K:Ca ratios increased significantly with increasing mean annual precipitation (MAP), whereas the P:K, P:Mg and Ca:Mg ratios decreased with the MAP. The biomass:N and biomass:Ca ratios decreased significantly with increasing soil N and Ca stocks, respectively. Forest stand age significantly affected biomass‐to‐nutrient ratios, with the older forests displaying higher biomass:N and biomass:P. The scaling relationships indicated that, on average, as biomass increased, biomass:N would increase, because N rose more slowly than linearly with biomass, whereas the Ca and Mg increased proportionally with biomass.Main conclusionsOur findings proved that the community‐level biomass‐to‐nutrient ratios and stoichiometry were affected by climate, soil, stand age and taxonomy of trees.

Effects of feeding frequency and protein source in milk replacer for Holstein calves

Whey proteins are a primary component of milk replacers (MR) and are considered the gold standard for calves. Alternative protein sources may decrease MR cost if calf performance is similar. A blend of bovine plasma protein and modified wheat protein might be a good partial replacement for whey protein. Usually MR is fed twice daily, but feeding 3 times daily might increase efficiency of nutrient use, especially with MR containing alternate proteins. Therefore, our objective was to determine the effects of 2 MR, containing either entirely whey protein (CON) or a combination of whey protein, bovine plasma protein, and modified wheat protein (WBP), when fed in either 2 or 3 meals daily on calf growth and health. Female and male Holstein calves (n = 103) housed in individual hutches were studied for the first 63 d of life, with additional measurements obtained at wk 12 of life in group housing. The MR contained 25% CP, 17% fat, and a Lys:Met ratio of 3.1:1. Individual treatments arose from the 2 × 2 factorial arrangement of MR formulation and frequency of feeding. After colostrum, calves were fed MR (12.5% solids) at daily rates of dry matter dependent on age. Amounts were as follows: d 3 to 10 = 0.52 kg/d (2× = 0.259 kg, 3× = 0.173 kg per feeding); d 11 to 20 = 0.68 kg/d (2× = 0.341 kg, 3× = 0.227 kg per feeding); d 21 to 42 = 0.84 kg/d (2× = 0.42 kg, 3× = 0.28 kg per feeding); d 43 to 46, 47, 49, and 51 = 0.42 kg/d, with both 2× and 3× changed to 1 feeding daily and skip days (d 48 and 50) between where calves were not given MR; and d 52 = calves weaned. Starter was fed and intake was measured from d 1 until d 63. Intakes, health scores, attitude scores, and fecal scores were measured daily. Body weight (BW) and growth measurements were obtained weekly until wk 8 and again at wk 12. Blood samples were obtained at 0, 24, and 48 h and then on d 5, 14, 28, and 42 of age. Starter intake was greater for calves fed WBP versus CON during wk 7 to 9. Final BW and hip width at wk 12 were greater for calves fed WBP than for calves fed CON. Calves fed 2× had greater mean and final BW to wk 6 and greater feed efficiency (gain:feed ratio) than calves fed 3×. Blood variables supported the generally similar growth outcomes. Health outcomes did not differ between diets or feeding frequencies. Overall, calves fed WBP had increased starter intake and greater BW gains during wk 7 to 12 than calves fed CON, and calves fed 2× had increased growth and feed efficiency compared with those fed 3×.

Biomass and concentration of nutrients and silicon in sugarcane grown on soil fertilized with diatomite

Silicon (Si) plays an important role in sugarcane, but there is a gap of information regarding the potential of diatomite as a Si fertilizer to this crop. Here, we assessed the effects of five rates (equivalents to 75; 150; 225; 300 and 375 kg ha-1 Si) of a diatomite-based fertilizer on the biomass yield and concentration of nutrients and Si in sugarcane plants grown on a sandy soil. The efficiency of the extractants acetic acid and calcium chloride in predicting Si uptake was also assessed. Results showed that diatomite was efficient in supplying available Si in the soil and increased Si concentration in the plant. The addition of diatomite significantly increased the available contents of P, K, Mn, Cu, and the cationic exchangeable capacity of the soil. The concentrations of N, P, Mn, Cu, and Zn in shoots were elevated, suggesting that the fertilizer can play a role in the efficient use of nutrients by sugarcane. The extractant 0.01 mol L-1 CaCl2 was better correlated with Si concentration in plants than 0.5 mol L-1 acetic acid. Therefore, CaCl2 is the recommended extractant to estimate Si availability because of its higher efficiency and lower cost.

Retrospective analysis of biochemical limitations to photosynthesis in 49 species: C4 crops appear still adapted to pre-industrial atmospheric [CO2

Leaf CO2 uptake (A) in C4 photosynthesis is limited by the maximum apparent rate of PEPc carboxylation (Vpmax ) at low intercellular [CO2 ] (ci ) with a sharp transition to a ci -saturated rate (Vmax ) due to co-limitation by ribulose-1:5-bisphosphate carboxylase/oxygenase (Rubisco) and regeneration of PEP. The response of A to ci has been widely used to determine these two parameters. Vmax and Vpmax depend on different enzymes but draw on a shared pool of leaf resources, such that resource distribution is optimized, and A maximized, when Vmax and Vpmax are co-limiting. We collected published A/ci curves in 49 C4 species and assessed variation in photosynthetic traits between phylogenetic groups, and as a function of atmospheric [CO2 ]. The balance of Vmax -Vpmax varied among evolutionary lineages and C4 subtypes. Operating A was strongly Vmax -limited, such that re-allocation of resources from Vpmax towards Vmax was predicted to improve A by 12% in C4 crops. This would not require additional inputs but rather altered partitioning of existing leaf nutrients, resulting in increased water and nutrient-use efficiency. Optimal partitioning was achieved only in plants grown at pre-industrial atmospheric [CO2 ], suggesting C4 crops have not adjusted to the rapid increase in atmospheric [CO2 ] of the past few decades.