Low Rate Applications Research Articles

The μ-RWELL layouts for high particle rate

The μ-RWELL is a single-amplification stage resistive Micro-Pattern Gaseous Detector (MPGD) . The detector amplification element is realized with a single copper-clad polyimide foil micro-patterned with a blind hole (well) matrix and embedded in the readout PCB through a thin Diamond-Like-Carbon (DLC) sputtered resistive film. The introduction of the resistive layer, suppressing the transition from streamer to spark, allows to achieve large gains (⩾104) with a single amplification stage, while partially reducing the capability to stand high particle fluxes. The simplest resistive layout, designed for low-rate applications, is based on a single-resistive layer with edge grounding. At high particle fluxes this layout suffers of a non-uniform response. In order to get rid of such a limitation different current evacuation geometries have been designed. In this work we report the study of the performance of several high rate resistive layouts tested at the CERN H8-SpS and PSI πM1 beam test facilities. These layouts fulfill the requirements for the detectors at the HL-LHC and for the experiments at the next generation colliders FCC-ee/hh and CepC.

Effects of biochar application on phreatic water evaporation and water-salt distribution in coastal saline soil

A 35-day simulated evaporation experiment was conducted to evaluate the effects of biochar application on phreatic water evaporation and water-salt distribution in coastal saline soil. Three biochar rates (0, 1%, and 5%; w/w) were applied to 65-cm-long soil columns. Results showed that applying the low biochar application rate effectively inhibited soil water evaporation. The 1% biochar treatment resulted in 4.4% lower cumulative soil water evaporation compared with the control, while it caused salt accumulation in the surface soil. By contrast, the high biochar application rate had little effect on cumulative soil water evaporation. Nonetheless, the 5% biochar treatment significantly increased the soil water-holding capacity while decreasing sodium adsorption ratio and salinity in the surface soil. In conclusion, applying a higher biochar rate (e.g., 5%) could improve salt water-distribution in the coastal saline soil under the experimental conditions.

The Influence of an Agricultural Subsidy Extension Program on Smallholder Maize Farmers in Tanzania

Smallholder farming in Tanzania is a household activity implemented at the subsistence level. The government of Tanzania launched the subsidy program to promote food secure households and shift subsistence farming to business farming. Food insecurity was associated by low rates of fertilizer application and poor seed quality among smallholder farmers due to fertilizer and seed costs which led to an increase in food prices. This study aimed at assessing the impact of the agricultural subsidy program for smallholder maize farmers. Four research objectives focused on agricultural productivity, food security, usage of improved inputs, and farmers’ perceptions of how the program functioned. An ex post facto research design was used with a sample of 120 smallholder farmers. The investigation involved 60 farmers who received subsidies and 60 who did not. The study used an interviewer administered questionnaire. Farmers who received subsidies significantly increased maize production. Comparison of average output before and after subsides shows an increase in number of bags (100 kg) per acre from an average of 5.35 bags to 10.10 bags. Farmers who did not receive subsides produced about the same amount of maize at time one and time two. There was general satisfaction with the functioning of the program, however certain areas need to be improved including that program objectives are followed, ensuring farmers can manage market price of inputs, and enhancing extension services for farmers to produce more surplus

The Influence of an Agricultural Subsidy Extension Program on Smallholder Maize Farmers in Tanzania

Smallholder farming in Tanzania is a household activity implemented at the subsistence level. The government of Tanzania launched the subsidy program to promote food secure households and shift subsistence farming to business farming. Food insecurity was associated by low rates of fertilizer application and poor seed quality among smallholder farmers due to fertilizer and seed costs which led to an increase in food prices. This study aimed at assessing the impact of the agricultural subsidy program for smallholder maize farmers. Four research objectives focused on agricultural productivity, food security, usage of improved inputs, and farmers’ perceptions of how the program functioned. An ex post facto research design was used with a sample of 120 smallholder farmers. The investigation involved 60 farmers who received subsidies and 60 who did not. The study used an interviewer administered questionnaire. Farmers who received subsidies significantly increased maize production. Comparison of average output before and after subsides shows an increase in number of bags (100 kg) per acre from an average of 5.35 bags to 10.10 bags. Farmers who did not receive subsides produced about the same amount of maize at time one and time two. There was general satisfaction with the functioning of the program, however certain areas need to be improved including that program objectives are followed, ensuring farmers can manage market price of inputs, and enhancing extension services for farmers to produce more surplus

The influence of biochar particle size and concentration on bulk density and maximum water holding capacity of sandy vs sandy loam soil in a column experiment

Biochar application to agricultural soils has been proposed as a way to increase crop production by improving soil chemical and physical properties. Liming potential and improved nutrient exchange on biochar surfaces are the most reported mechanisms. Wherever crops experience drought stress, improvements in soil water holding capacity (WHC) might also be an important mechanism. However, reported effects on soil structure and WHC are mixed. Therefore, we studied the effects of biochar on soil bulk density (BD) and WHC in a laboratory column study using two agricultural soils from Portugal: a sandy and a sandy loam soil. Mixed woody feedstock was pyrolysed at 620 °C, creating a wettable biochar that was used unsorted as well as sieved into large (2–4 mm) and small (0.05–1.00 mm) particles, mixed into the soils at 1, 5, 10 and 20% (by volume), and incubated for 10 days at field capacity to allow aggregation. Soil samples were analysed for BD and WHC using soil columns.We found biochar to decrease soil BD and increase maximum WHC, expressed as gravity-drained equilibrium water content, for both soils. The sandy soil was more responsive with significant effects at the lowest application rate (1%), while the sandy loam soil started to show significant effects at 5% biochar. Small biochar particles reduced the BD of sandy soil more, while large biochar particles caused a greater reduction in the BD of the sandy loam soil. The effect of biochar particle size on WHC was less clear, except for small particles at 20% volumetric concentration, which showed a 60% increase in gravimetric WHC. When expressed as total soil water storage (SWS), 20% biochar incorporation to 15 cm depth would increase the total SWS of sandy soil from 0.56 mm (control) to 0.83–0.91 (mm), and of the sandy loam soil from 0.56 to 0.79–0.96 (mm), depending on biochar particle size. Our results suggest that biochar particle sizes can be used to achieve specific effects in soils, while mechanisms and trade-offs (agro-economic and environmental) need further exploration.

Effect of Soil Treatments for Cottony Cushion Scale (Hemiptera: Monophlebidae) Control on Nylanderia fulva (Hymenoptera: Formidicae) Survival and Trailing Activity

Nylanderia fulva (Mayr) (Hymenoptera: Formicidae), or tawny crazy ant, is an invasive ant from South America that is spreading in the southern US. Extremely large populations of this ant can inundate urban and natural landscapes, and efficient control methods are lacking. This study was conducted to determine if activity of N. fulva would decline after controlling the hemipteran honeydew-producers they were tending. Potted plants infested with cottony cushion scale (Icerya purchasi Maskell) (Hemiptera: Monophlebidae) were treated with 2 imidacloprid insecticide formulations, and changes in N. fulva survival and foraging behavior were monitored. There were fewer ant trails, lower trailing intensity, less foraging, and less nesting in potted plants treated with either product than in the control pots. The use of low application rates of systemic insecticide to reduce honeydewproducing hemipterans, such as cottony cushion scale, could be an important component of the integrated pest management of N. fulva.

Effects of fly ash application on plant biomass and element accumulations: a meta-analysis

Fly ash generated from coal-fired power plants is a source of potential pollutants, but can be used as a soil ameliorant to increase plant biomass and yield in agriculture. However, the effects of fly ash soil application on plant biomass and the accumulation of both nutrient and toxic elements in plants remain unclear. Based on 85 articles, we conducted a comprehensive meta-analysis to evaluate changes in plant biomass and concentrations of 21 elements in plants in response to fly ash application. These elements included macro-nutrients (N, P, K, Ca, and S), micro-nutrients (B, Co, Cu, Fe, Mn, Mo, Ni, and Zn), and metal(loid)s (Al, As, Cd, Cr, Pb, and Se). Overall, fly ash application decreased plant biomass by 15.2%. However, plant biomass was enhanced by fly ash application by 11.6–29.2% at lower application rates (i.e. <25% of soil mass), and decreased by 45.8% at higher application rates (i.e. 50–100%). Belowground biomass was significantly reduced while yield was enhanced by fly ash application. Most of the element concentrations in plants were enhanced by fly ash application, and followed a descending order with metal(loid)s > micro-nutrients > macro-nutrients. Concentrations of elements tended to increase with an increase in fly ash application rate. Our syntheses indicated that fly ash should be applied at less than 25% in order to enhance plant biomass and yield but avoid high accumulations of metal(loid)s.

Improving grey water footprint assessment: Accounting for uncertainty

The grey water footprint (GWF) refers to the amount of freshwater required to dilute pollutants to meet water-quality standards. The aim of this paper was to estimate the GWF and its uncertainty for crop production at the basin scale. The proposed approach was tested in the Rio Mannu Basin (Sardinia, Italy) for durum wheat production. The fraction of nutrients flowing into the river and groundwater was evaluated using the Soil and Water Assessment Tool model that was calibrated with in-stream monitoring data. A bootstrap technique coupled with Monte Carlo simulations was used to estimate the uncertainty of the GWF due to the variability of the primary input data and the unknown natural background level of nutrients in the waters. The GWF for total phosphorus (TP) input (3284 m3 t−1) was higher than that for dissolved inorganic nitrogen (DIN) (275 m3 t−1), despite the lower rate of phosphorus fertiliser application. The uncertainty was found to be relevant for both DIN (60%) and TP (18%). The environmental sustainability of durum wheat production was assessed throughout the water pollution level. This showed that the TP load exceeded the assimilation capacity at the reach scale, and that further analyses are needed to assess the environmental sustainability at the basin scale.

Effects of ZnSO4 and Zn‐EDTA applied by broadcasting or by banding on soil Zn fractions and Zn uptake by wheat (Triticum aestivum L.) under greenhouse conditions

AbstractZinc biofortification of staple food crops is essential for alleviating worldwide human malnutrition. Agronomic interventions to promote this should include fertilizer selection and management. A chelated Zn source, Zn‐EDTA, and an inorganic Zn source, ZnSO4 × 7 H2O, were applied either by banding or by broadcasting in soil, and Zn fractions in soil and Zn uptake by wheat were determined in a pot experiment. Compared to ZnSO4 × 7 H2O, Zn‐EDTA produced higher Zn concentration in grain regardless of application method and even at a lower application rate. Residual Zn fraction was the largest Zn fraction with both ZnSO4 and Zn‐EDTA amendment. ZnSO4 banded in soil caused Zn fractions to be restricted to the Zn‐amended soil band and resulted in lower grain Zn concentrations than did broadcast ZnSO4. Planting wheat slowed Zn fixation by promoting the maintenance of a high concentration of Zn fraction loosely bound to organic matter (LOM‐Zn) in soil. Zn‐EDTA was a better Zn source for Zn biofortification of wheat than was ZnSO4.

Effect of N-modified lignite granulates and composted biochar on plant growth, nitrogen and water use efficiency of spring wheat

ABSTRACTOrganic soil amendments such as biochar are increasingly used to improve the fertility of degraded soils and marginal lands, plant growth, water retention and carbon sequestration. The performance of biochar depends on the parent material, the pyrolysis conditions and the nutrient enrichment process, accounting for the variability of the final products. Recently lignite granulates came into focus offering an alternative characterised by homogeneity, vast availability of the raw material and a standardised production process including nitrogen enrichment through oxidative ammonolysis. In a greenhouse experiment the effects of N-modified lignite granulates (NLG) and composted biochar (BC) on the growth of spring wheat (Triticum aestivum) in a sandy, carbon-free substrate were compared. Additionally, the effect of different NLG application rates (5, 7.5, 11, 15, 28 t ha−1) was investigated. Yields as well as nitrogen and water use efficiency of the soil-plant system were determined at the end of the experiment. Both organic amendments increased yields relative to control plants. An increase in yield, nitrogen and water use efficiency for NLG even at low application rates and a better growth performance compared to BC were observed. Present findings, therefore, indicate, that such granulates offer an alternative to existing organic soil amendments.

Increased risk of phosphorus and metal leaching from paddy soils after excessive manure application: Insights from a mesocosm study

Livestock manure has gradually become an alternative fertilizer for maintaining soil fertility, whereas excessive application of manure leads to the release of phosphorus (P) and toxic metals that may cause complex environmental risks. To investigate the accumulation and migration of P within soil profiles, a mesocosm experiment was conducted to analyze the content and leaching of soil P, metals, and dissolved organic carbon after different fertilization treatments, including control (no fertilizer, CK), chemical fertilizer (CF), chemical fertilizer combined low (CF + LPM) and high (CF + HPM) rate of manure application. Results showed that a high rate of manure application significantly enhanced the accumulation of total soil P (by ~14%) and P availability (easily-available P, by ~24%; Olsen-P, by ~20%) in topsoil, and also increased the content of easily-available organic P (EA-Po) in both topsoil and subsoil compared to the CK treatment. The migration of dissolved inorganic and organic P (DIP and DOP) in leachate within soil profiles was strengthened by manure application. Moreover, significant positive correlations between P, metals, and dissolved organic carbon (DOC) in leachate indicated that downward co-migration occurred within the soil profiles, and also suggested that excessive manure application can intensify the risk of P loss by increasing the migration of manure-derived DOC. Overall, our findings provide insights into P accumulation and migration within soil profiles after excessive manure application, which is useful for predicting the potential risk of P and metal leaching from paddy soils.

EFFECT OF NOZZLES, APPLICATION RATES, AND ADJUVANTS ON SPRAY DEPOSITION IN WHEAT CROPS

ABSTRACT The use of insecticides is common in pest management in wheat crops but may lead to higher production costs and environmental contamination. Therefore, a more comprehensive and uniform distribution of plant protection products in the desired target is recommended. The objective of this study is to evaluate the effect of different spray nozzles, application rates, and adjuvants on droplet spectrum and spray deposition in wheat crops. The physicochemical characteristics of the spray mixture, droplet spectrum, and spray deposition in wheat plants were evaluated. The lower application rate (75 L ha−1) combined with the use of the twin flat fan tip AS7030 and the adjuvant sodium lauryl ether sulfate (SLES) yielded droplets with a larger diameter. However, insecticide spraying using hollow cone tip MGA 015 without adjuvants provided the highest percentage of droplets susceptible to drift. SLES significantly decreased the percentage of drift by increasing droplet size, and the adjuvant silicone, d-limonene, and polyester copolymer increased spray deposition. The evaluated adjuvants increased the electrical conductivity and reduced the surface tension of the spray mixtures. These results indicate that it is possible to reduce the application rate from 150 to 75 L ha−1 without affecting spray deposition on wheat leaves.

Cleaner Production in small companies: Proposal of a management methodology

Global level agreements related to sustainability have changed the way organisations work. Many companies, mainly the larger ones, have assessed their environmental impacts to achieve both economic and environmental benefits by reducing waste generation and by using less energy, water, and materials. Considering this approach, many of these companies have strategically set up environmental management practices guided by Cleaner Production (CP) concepts. Despite its benefits, CP has a low application rate in small and medium-sized enterprises (SMEs), which is attributed to barriers such as a lack of resources, concentrated decision-making by owners and lack of leadership. Based on CP concepts and focusing on overcoming internal barriers in SMEs, this article proposes a management methodology of CP in small companies. A longitudinal action research of six cycles was carried out to develop a suitable methodology, comprising a meta phase and a five-step cyclic phase, which was a simple and viable way of conducting a CP program. It was found that promotion and monitoring actions, prioritisation of preventive opportunities and employee involvement facilitate the process of continuous improvement. This methodology may facilitate SME environmental management and contribute to developing products and processes towards sustainability objectives more efficiently.

Increased N fertilizer input enhances CH4 and N2O emissions from soil amended with low amount of milk vetch residues

The combined use of chemical N fertilizer and crop residue could influence greenhouse gas emissions in agriculture. A pot experiment was performed to examine the combination of milk vetch residue and chemical N fertilizer and the amount of total N input on CO2, CH4 and N2O emissions from paddy soils. Neither fertilizer combination nor fertilizer amount influenced cumulative CO2 emissions. Cumulative CH4 emissions increased with increasing proportion of milk vetch residues. Nevertheless, with low milk vetch residue application rate, increased chemical N fertilizer input significantly enhanced CH4 emissions. Cumulative N2O emissions from soils amended with low and moderate amount of milk vetch residues were promoted by increased N fertilizer input. By contrast, N2O emissions from soils without milk vetch residue application or amended with high milk vetch residues were not influenced by increment of N fertilizer. It was concluded that both CH4 and N2O emissions were promoted by increased N fertilizer, which might be due to the microbial activity and N immobilization in soils amended with different amounts of milk vetch residues.

Impact of Infiltration Rate on Residual Air Distribution and Hydraulic Conductivity

Core Ideas Infiltration experiments were conducted on a sample under two boundary conditions. Time‐lapse neutron imaging was used to determine water distribution in the sample. Significant air entrapment was detected in the case of slow drip irrigation infiltration. Gravity‐driven ponding infiltration led to much less air entrapment. Air entrapment led to one order of magnitude lower conductivity in the case of drip irrigation. The dynamics of water infiltration into soil have a strong influence on the subsequent distribution of air trapped inside pores. We present results of two infiltration experiments conducted on an artificially prepared sample under ponding and drip irrigation boundary conditions, with concurrent neutron imaging of the sample. A cylindrical sample was packed with two grades of sand and disks of fine porous ceramic in an axially symmetrical geometry. The configuration of the sample provided a number of interfaces between regions of higher and lower hydraulic conductivity. Infiltration was started in dry media. The bottom boundary condition was seepage face. Water was applied on the sample surface during the experiment with drip irrigation at a water application rate about one order of magnitude lower than the minimum flux reached during the ponding experiment. Despite this low application rate, ponding eventually occurred on the top of the sample due to an unexpectedly low infiltration rate. Neutron tomographic imaging revealed massive air entrapment in the coarse sand regions of the sample during slow infiltration under drip irrigation conditions. In contrast, during the ponded infiltration experiment, the air was mostly flushed out from the coarse sand regions by gravity‐driven water flow due to greater hydraulic head. Neutron imaging showed that the capillary barrier effect, air entrapment, and entrapped air redistribution were responsible for the observed low infiltration capacity of the sample during the slow‐infiltration‐dominated drip irrigation experiment. It is reasonable to assume that similar phenomena can occur in natural soils having highly heterogeneous structures.

Comparing the effectiveness and longevity of the urease inhibitor N-(2-nitrophenyl) phosphoric triamide (2-NPT) with N-(n-butyl) thiophosphoric triamide (nBTPT) in reducing ammonia emissions from cattle urine applied to dairy-grazed pasture soils

The objective of this laboratory incubation study was to assess the effectiveness and longevity of urease inhibitor N-(2-nitrophenyl) phosphoric triamide (2-NPT), along with the commonly used N-(n-butyl) thiophosphoric triamide (nBTPT), in reducing ammonia (NH3) emissions from cattle urine applied to pasture soils. It was hypothesised that 2-NPT would be effective as a longer-lasting inhibitor to reduce emissions after the deposition of urine during multiple grazing events. Two dairy-grazed pasture soils (Fluvisol, Rangitikei loamy sand (RLS) and Andosol, Egmont black loam (EBL)) with contrasting organic carbon levels and urease activity were used. The following treatments were applied to the soils at the start of the experiment: no inhibitor, nBTPT-low, 2-NPT-low, 2-NPT-medium and 2-NPT-high. Urine-N was applied to all the treatments at four stages: immediately before inhibitor application (Stage A), 29 days after inhibitor application (Stage B), 56 days after inhibitor application (Stage C) and 29 days and again 60 days after inhibitor application (Stage D); NH3 emissions were measured up to Day 31 after each urine application. The low, medium and high application rates of inhibitors were determined based on achieving 0.025%, 0.050% and 0.075% of quantity of urine-N applied in Stage A respectively. For the no inhibitor treatment, the proportion of total applied N in urine that was emitted as NH3 for the different stages ranged from 35.8% to 50.5% for RLS soil and from 14.2% to 26.7% for EBL soil. For Stage A, both inhibitors equally reduced NH3 emissions from applied urine in both soils (23.7–27.3% for the RLS and 20.6–27.2% for the EBL). For Stage B, significant reductions (4.2–13.4%) in NH3 emitted was observed only from RLS soil, with there being a significantly greater reduction from 2-NPT than from nBTPT, and 2-NPT continued to reduce NH3 emissions at Stage C (5.6–7.4%). There was no reduction in emissions during Stage D by either of the inhibitors. The results of this study suggest that 2-NPT can extend the longevity of urease inhibition and reduce NH3 emissions compared with the more commonly used inhibitor nBTPT in dairy-grazed pasture soils.

Process Optimization Potassium Nanofertilizer Production via Ionotropic Pre-gelation using Alginate-Chitosan Carrier

Potassium nanofertilizer synthesis by incorporating potassium in alginate-chitosan carrier via ionotropic pre-gelation was optimized to maximize potassium content and develop controlled release fertilizer. Utilizing two-level factorial design, potassium to alginate ratio, calcium chloride to alginate ratio, and pre-gelation time were determined significant. Central Composite Design for optimization was utilized to generate a Response Surface model relating the factors to the response for numerical optimization. Optimum process conditions for maximum potassium content were (1) 1.5:1 (w/w) potassium to alginate ratio, (2) 6.5:117.5 (v/v) calcium chloride to alginate ratio, and (3) 40 minutes pre-gelation time. The potassium content of the fertilizer formulated at optimum condition was successfully verified to contain 29.75 %K(w/w). Characterization showed that potassium was successfully incorporated in the alginatechitosan carrier as shown by the SEM surface images. DLS result showed two peaks at particle sizes near 594.1 nm and 102.8 nm indicating that potassium nanofertilizer was successfully synthesized. Potassium nanofertilizer may be a controlled release fertilizer since only 14.6 %K was released after 24 hours in Britton-Robinson buffer solution. Preliminary costing shows higher cost of production based on raw materials, but it may be offset in the long run by longer availability of nutrient and low fertilizer application rate.

Evaluation of the phytotoxicity of coal ash on lettuce (Lactuca sativa L.) germination, growth and metal uptake

Land application of coal ash is considered an environmentally friendly option to improve soil quality, but limited information exists on metal bioavailability and phytotoxicity of coal ash to sensitive plant species such as lettuce (Lactuca sativa L.). Germination and pot bioassay experiments were conducted at six coal application rates (0% (control), 5%, 15%, 25%, 50% and 75% v/v) to investigate the hypothesis that, coal ash will have a hormetic effect on germination, growth, metal uptake and biomass yield of lettuce, characterized by stimulatory and phytotoxicity effects at low and high application rates, respectively. Total concentrations (mg/kg) of metals in coal ash spanned several orders of magnitude, and decreased in the order: Fe (5150.5), Mn (326.0), Zn (102.6), Cu (94.7), Ni (74.7) and Pb (11.6). Bioavailable concentrations of metals were very low (0.0–14.1 mg/kg), accounting for less than 2% of the total concentrations. Coal ash had no significant effect on germination indices, but had hormetic effects on radicle elongation, evidenced by stimulatory and phytotoxicity effects at low (5–25%) and high (50–75%) application rates, respectively. Coal ash application at 50% and 75% significantly (p < 0.05) reduced lettuce growth and edible biomass yield, but lower application rates (5–25%) were similar to the unamended soil (control). Fe, Mn, Zn, Cu and Ni bioavailability and plant uptake generally decreased with increasing coal ash application rates particularly at 50% and 75%. Soil pH significantly increased (p < 0.05) from 6.5 for the control to about 8 for 75% coal ash, while electrical conductivity (EC) increased by 2–7 times to about 0.9 and 1.5 dS/m at 50% and 75% coal ash, respectively. Significant inverse linear relationship (p < 0.05; r2 = 0.80) were observed between edible and total biomass yields and EC, suggesting that increased salinity at high coal ash application rates could account for reduced growth and biomass. Partial elemental balances showed that plant uptake of metals was very low, accounting for just less than 2% of the bioavailable concentrations, while the bulk of the metals (98–99%) remained in the soil. In conclusion, the current findings show that coal ash may have hormetic and phytotoxic effects on sensitive plant species, an observation contrary to the bulk of earlier literature documenting beneficial effects of coal ash application to soils. Long-term field studies are required to confirm the current findings based on laboratory and pot bioassay experiments.

Soil dwelling beetle community response to tillage, fertilizer and weeding intensity in a sub-humid environment in Zimbabwe

Soil dwelling beetles contribute greatly to biodiversity and offer important services in agroecosystems including predation, weed herbivory and decomposition. An experiment was conducted in the 2013/2014 and 2014/2015 cropping seasons at Chinhoyi University of Technology experiment station, Zimbabwe, to investigate the impact of tillage system (conservation tillage and conventional tillage), fertilizer application rate and weeding intensity on beetle communities in maize. The experiment was laid out in a split-split plot using a randomized complete block design and replicated three times. Beetles were sampled using un-baited pitfall traps. A total of 6020 beetles were collected comprising 53 species, nine families and four functional groups. Tillage system had the strongest effects on beetle diversity. Advanced constrained analysis using principal response curves revealed that the abundances of Anchophthalmus oncotipes decreased under conservation tillage. In contrast, abundances of Zophosis boei, Gonocephalum simplex, Renatiella reticulata and Stenethmus tentyriniformis increased under conservation tillage relative to conventiona tillage (CT). Detritivore abundances were 50.8% and 45% greater under rip line seeding than CT during the hot dry season of 2014 and cold dry season of 2015, respectively. Predator abundances were almost double in basin planting relative to CT during the cold dry season of 2014 and hot humid season of 2015. In the 2014/2015 cropping season, maize grain yield significantly increased (P < 0.05) from 4963 kg ha−1 in CT to 7848 kg ha−1 in basin planting tillage. Application of a high rate of fertilizer increased maize grain yield by 31.2% compared to the low and medium fertilizer application rates. Weeding twice resulted in the highest maize grain yield but there was no yield benefit in increasing weeding intensity more than twice per season. Our results suggest that there is potential for increasing density and diversity of beneficial beetle species through conservation tillage with crop residue retention.

Assessing the impact of fertilizer application on net soil-derived emission budgets from a temperate willow (Salix miyabeana) short rotation coppice system

Willow (Salix spp.) short-rotation coppice (SRC) systems are productive bioenergy feedstocks that can be cultivated on marginal land and generate high yields when amended with nitrogen (N) fertilizers. However, fertilizer application results in greater N2O emissions and negates the potential carbon (C) neutrality of willow bioenergy systems. We evaluated 1) the effect of N fertilizer application on the soil-atmosphere exchange of CO2-C and (N2O-N emissions, soil NH4+-N and NO3−-N); 2) emissions generated during winter and freeze-thaw cycles (FTCs); and 3) the net annual emission (CO2-equivalents [CO2-eq]) from willow SRC systems. CO2-C emissions followed seasonal trends with elevated emissions occurring in the spring and summer. Significantly greater (p < 0.05) CO2-C emissions were observed during the growing season, whereas only 7.2%–13.4% of the total CO2-C emissions occurred during the winter. Freeze-thaw cycles (FTCs) did not significantly (p < 0.05) increase CO2-C emissions. Nitrogen fertilizer application increased soil NH4+ and NO3− availability resulting in an N2O-N hot moment following fertilizer application in the spring. There was a N2O-N hot moment following FTC events, and winter N2O-N emissions were minimal. Overall, N2O-N emissions accounted for 2.2–3.4% of the total annual emissions. Willow SRC systems were a C sink in fertilized treatments with a C sequestration potential of 10.79 Mg CO2-eq ha−1 yr−1. Unfertilized treatments were a slight C source, with net emissions of 1.19 Mg CO2-eq ha−1 yr−1. We recommend a low rate of fertilizer application to willow SRC systems to maintain these systems as a long-term C sink.