Effect of Nitrogen Fertilizer on Grain Yield and Nitrogen Use Efficiency in Corn (Zea mays L.) Hybrids Under Irrigated Conditions

In order to study the effect of nitrogen rates on grain yield and nitrogen use efficiency of corn (Zea mays L.) hybrids, a field experiment was conducted in south-western Iran during 2011–2012. The experiment was split-plot with RCBD arrangement in three replications. Main plots consisted of four nitrogen rates (0, 90, 180 and 260 kg N ha^?1) and four corn hybrids (Sc.704, Sc.640, Mobeen and DKC6589) were placed in sub-plots. Results indicated that the effect of nitrogen, hybrids and their interaction on corn grain yield was significant. Increase in nitrogen rates from 0 to 90, 180 and 260 kg N ha^?1 increased the mean grain yield studied hybrids by 42.6, 55 and 58 %, respectively. DKC6589 hybrid and Mobeen had the highest and lowest grain yield among studied hybrids. Higher grain yield in DKC6589 was due to higher number of grains per ear and 100-grain weight. The results of step-wise regression coefficients also indicated that number of grains had the maximum contribution in grain yield. As compared to grain yield of Mobeen and Sc.640 hybrids at the levels of 180 and 260 kg N ha^?1, DKC6589 hybrid yield was more in the treatment of no nitrogen. The maximum grain yield was obtained in DKC6589 hybrid and 180 kg N ha^?1. Increase of nitrogen up to 260 kg N ha^?1 led to the significant increase in grain yield of 640 hybrid, but in other hybrids, increase of nitrogen up to more than 180 kg N ha^?1, slightly decreased the grain yield. There was genetic variation for nitrogen use efficiency. It is possible to select hybrids with higher nitrogen use efficiency to reduce the fertilization. Positive and significant relation between grain yield and nitrogen use efficiency was marked. DKC6589 hybrids as compared to other hybrids had more nitrogen use efficiency and agronomic nitrogen use efficiency in lower amount of fertilizer. Generally, it seemed that DKC6589 hybrid had all ideal traits of implantation in the region as the potential of its grain yield was very high.     

Effect of Organic Sources of Nutrients on Tuber Bulking Rate,Grades and Specific Gravity of Potato Tubers

A field experiment was conducted during 2008–2009 and 2009–2010 to investigate the effect of organic sources of nutrients on tuber bulking rate, grades and specific gravity of potato tubers. The experiment consisted 24 treatment combinations with 8 treatment in popcorn [control, recommended dose of fertilizers (N₁₂₀P₂₅K₃₅ kg ha^?1), farmyard manure equivalent to 120 kg N ha^?1, leaf compost equivalent to 120 kg N ha^?1, vermicompost equivalent to 120 kg N ha^?1, farmyard manure equivalent to 90 kg N ha^?1, leaf compost equivalent to 90 kg N ha^?1 vermicompost equivalent to 90 kg N ha^?1 in succeeding crop of potato, three treatments [control, farmyard manure equivalent to 60 kg N ha^?1 and farmyard manure equivalent to 90 kg N ha^?1] were superimposed on the different treatments of pop corn. It was found that the application of farmyard manure equivalent to120 kg N ha^?1 to pop corn and farmyard manure equivalent in 90 kg N ha^?1 in potato gave the highest values of tuber bulking rate, specific gravity, number of large–sized (A–grade) and medium–sized tubers (B–grade) and total tuber yield followed by vermicompost equivalent to to 120 kg N ha^?1. Farmyard manure equivalent to 90 kg N ha^?1 to potato also recorded the higher bulking rate, tuber yield, specific gravity and a number of large sized tubers (A– grade and B–grade) as compared to the farmyard manure equivalent to 60 kg N ha^?1. The available N, P, and K in soil also improved with the application of organic manures.     

Bio-efficacy of Herbicides on Performance of Mustard, <Emphasis Type="Italic">Brassica juncea</Emphasis> (L.) and Population Dynamics of Agriculturally Important Bacteria

The bio-efficacy of different herbicide treatments on the performance of mustard crop and its effect on population dynamics of beneficial soil microorganisms like Azotobacter (aerobic and free-living nitrogen fixing bacteria), Bacillus and Pseudomonas (phosphate solubilisation and biocontrol agents) were studied. Higher doses of pendimethalin (@1.0 kg ha^?1) and isoproturon (@1.0 kg ha^?1) had toxic effect on the germination (13.33 and 17.33 m^?2) and emergence of mustard crop and resulted in significantly lower plant population. These treatments resulted in reduction of plant population to the tune of 47.92 and 31.48 % at 30 days after sowing (DAS) and 47.06 and 27.96 % at harvest. Weed free treatment recorded significantly higher seed yield (2781 kg ha^?1) which was about 99 % more than the weedy check. The increase in seed yield with different herbicides was to the tune of 27–73 % over weedy check, except pendimethalin @1.0 kg ha^?1 as pre-emergence (PE). The weedy check plot showed highest population of Azotobacter, Bacillus, and Pseudomonas throughout the observation period. However, among different herbicide treatments, the highest population of Azotobacter and Bacillus was observed with pendimethalin 0.5 kg ha^?1 as PE and that of Pseudomonas with isoproturon 1.0 kg ha^?1 30 DAS at harvest stage.     

Effect of Mycorrhizal Infection on Phosphorus Efficiency of Maize (Zea mays L.) Cultivars

Phosphorus is considered as one of the least available plant nutrients found in the rhizosphere. The large variation in phosphorus acquisition efficiency of different crop cultivars provides opportunities for screening cultivars that perform well on low phosphorus soil for sustainable agriculture. To assess phosphorus efficiency of maize cultivars viz.: Paras and JH 3459, a field experiment was conducted for 2 years at Indian Institute of Technology, Kharagpur, India on sandy loam soil, having pH 5.1, organic carbon 4.1 g kg^?1 soil and as low as 11.2 kg ha^?1 available phosphorus. Phosphorus was applied at a rate of 0 (low) and 400 kg ha^?1 (high) with and without the application of fungicide Benomyl at 500 kg ha^?1 for eradication of arbuscular mycorrhiza. Maize plants were harvested at 24, 48, and 74 days after sowing and final harvest was taken at maturity. In low phosphorus soil without Benomyl, cv. Paras produced 29, 18, and 69 %, while cv. JH 3459 produced 19, 9, and 57 % of their maximum shoot dry weight at 24, 48, and 74 days after sowing, respectively during the first year and the trend was same during the second year. The results indicate that relative shoot dry weight varies with growth stages and therefore, grain yield should be used to assess phosphorus efficiency. At maturity, maize cv. Paras produced 91 and 80 % while JH 3459 produced 71 and 60 % of their maximum grain yield during the first and second year respectively, proving that cv. Paras was more phosphorus efficient than cv. JH 3459. Root growth of both the cultivars was restricted under phosphorus deficiency conditions; however, cv. Paras produced 1.4–2.6 times more root length than cv. JH 3459 at different growth stages. Cultivar Paras had lower phosphorus influx than cv. JH 3459, but it was more phosphorus efficient because of more roots, lower internal phosphorus requirement and higher root length/shoot dry weight ratio. Application of Benomyl was completely effective in suppressing arbuscular mycorrhiza infections up to 48 days after sowing. Its effect started diminishing thereafter and some infection occurred, which however was significantly less than that observed in untreated plots. Thus, the yield difference between Benomyl treated and untreated plots can be attributed to arbuscular mycorrhiza. In low phosphorus soil, Benomyl application reduced the growth of cultivars by 12–45 % and the maximum reduction of growth was at 48 days after sowing. However, in high P soil, Benomyl application had no significant effect on dry matter yield of the cultivars.     

Efficient Nitrogen and Water Management for the Soybean–Wheat System of Madhya Pradesh,Central India,Assessed Using APSIM Model

A series of long-term simulations were carried out to investigate alternative management practices to increase grain yields of soybean and wheat by optimizing sowing dates, nitrogen (N) and water requirements, along with complimenting farmyard manure (FYM) as a N source in the soybean–wheat cropping system of Madhya Pradesh. The APSIM simulation study showed that the mean soybean yield ranged from 1.0 to 1.6 t ha^?1 for the different dates of sowing. The average wheat grain yield was 3.2–3.9 t ha^?1, whereas, the crop sown on 15 November gave the highest yield. In this region, there is a potential to increase soybean and wheat yields by 0.6 and 2.2 t ha^?1, respectively. Among the various irrigation practices simulated, five irrigations of 60 mm at 20 days interval was the best option for wheat. Application of 16 t FYM ha^?1 to soybean produced 50 % higher wheat yield than the same amount of FYM applied to wheat. The wheat yield obtained from inorganic application of N was at par with that obtained from the application of integrated and organic sources. However, the amount of N loss from the integrated use of fertilizer N was lower than that from the current recommended practice for the region. Application of FYM alone or in combination with inorganic fertilizer maintained higher soil organic carbon concentration as compared to the application of inorganic fertilizer alone. Thus, the model provided a mean of evaluating alternative crop N and water management options for effectively managing the soybean–wheat cropping system.     

Effects of Resource Conservation Practices on Productivity,Profitability and Energy Budgeting in Maize–Wheat Cropping System of Indian Sub-Himalayas

Resource conservation issues have drawn the attention of scientists to devise innovative tillage and crop establishment techniques for higher productivity in small holder farming systems in the tropics but relatively less attention has been given in rainfed sloping lands of the Indian sub-Himalayan (sub-temperate) regions. To investigate these issues, an experiment was conducted on resource conservation practices under rainfed conditions for 5 years (June 2007–May 2012) at Dehradun, Uttarakhand in the Indian Himalayan region. Four treatments, 1. 100:60:40 kg N:P₂O₅:K₂O + conventional tillage (CT) + chemical weeding + PANICUM vegetation strip (T₁); 2. FYM (5 t ha^?1) + minimum tillage (MT) + 1 weed mulch (30 DAS) @ 0.52 t ha^?1 + PALMAROSA vegetation strip (T₂); 3. FYM (5 t ha^?1) + vermi-compost (1.0 t ha^?1) + MT + 2 weed mulch (25 and 50 DAS) @ 1.47 t ha^?1 + PALMAROSA vegetation strip (T₃) and 4. FYM (5 t ha^?1) + vermi-compost (1.0 t ha^?1) + poultry manure (2.5 t ha^?1) + MT + 3 weed mulch (20, 40 and 60 DAS) @ 2.18 t ha^?1 + PALMAROSA vegetation strip (T₄). The results showed that resource conservation treatments (T₄, T₃ and T₂) had significant (P ≤ 0.05) multiple benefits as compared to traditional agriculture treatments (T₁). T₁ gives the highest yield of maize whereas T₄ gives highest yield of wheat. For the maize–wheat cropping system, mean wheat equivalent yield (WEY) was ~16 % higher in T₄ than T₁. Mean runoff was ~30 % lesser and mean soil loss was ~34 % lesser in T₄ as compared with T₁. Similarly, mean soil moisture conservation for rainfed wheat was ~31 % higher in T₄ than T₁. Mean carbon retention potential increased by ~53 % which subsequently increased mean soil quality index (SQI) by ~25 %. Mean energy productivity increased by ~70 % and mean energy intensiveness decreased by ~56 % in T₄ than T₁. Treatment T₁ (2,560 MJ^?1) emerged to be the most energy intensive system as compared to T₄ (1,113 MJ Rs.^?1). On an average, T₄ had 7 % higher net returns than T₁ and in terms of net returns per tonne of soil loss, T₄ was the best treatment (Rs. 4,907). Therefore, resource conservation system (PALMAROSA as a vegetation strip along with organic amendments, FYM, vermi-compost, poultry manure and weed mulch under minimum tillage) had significant positive impact on yield, resource conservation and energy saving and may be introduced as a substitute of conventional system in the Indian sub-Himalayas and under similar climatic and edaphic conditions.     

Effects of fertiliser applications after thinning of Pinus radiata on a high-elevation site in south-eastern Australia

A trial to assess the effects of fertiliser applied after thinning was established in a ten-year-old Pinus radiata stand growing on a high elevation site in south-eastern Australia. The trial had two components. The first studied the effects of fertilisers applied in a factorial design with two levels of phosphorus (0 and 50 kg P ha^–1) and three of nitrogen (0, 150 and 300 kg N ha^–1) plus a mixed nutrient treatment to areas thinned to a routine intensity. In the second part, levels of thinning intensity were assessed with and without a fertiliser (N₁P₁) application. Over the seven years of the study, growth was affected by below average rainfall in four of the years. Significant responses to fertiliser were achieved with all treatments; the best was 150 kg N ha^–1 + 50 kg P ha^–1 plus trace elements. The volume increment was increased by 28%, however this was not significantly different from the N₁P₁ alone. The N₁P₁ fertiliser increased productivity at all thinning levels including the unthinned treatment. Models predicting relative growth response based on foliage nutrient levels gave reasonable predictions, that is, 29% increase in volume periodic increment and this was slightly higher than that achieved. On such low rainfall sites, rather than having multiple thinnings, one option is a relatively heavy thinning at a young age with fertiliser application and then leaving the stand until final harvest. Estate optimisation models provide forest managers with the means to evaluate fertiliser-thinning treatment options against objectives such as maximising the present value of expected future cash flow within production and budget constraints.     

Fertilization and Crop Residue Addition Impacts on Yield Sustainability Under a Rainfed Maize–Wheat System in the Himalayas

A 9-year old experiment was conducted at Almora, India to study the effects of mineral sources of nutrients in different combinations with or without crop residue or farmyard manure (FYM) addition on crop productivity under a rainfed maize–wheat system. Plots under 100 % nitrogen–phosphorus–potassium (NPK) + FYM had maximum mean maize (5.00 Mg ha^?1) and wheat (2.61 Mg ha^?1) yields that were generally significantly higher than yields observed under other treatments. Total soil organic carbon (C) increased in all treatments except with mineral fertilization and control plots. While NPK treated plots had significantly higher benefit:cost ratio than NPK + FYM plots, organic C content in the NPK treated plots decreased over the initial soil and FYM treated plots had better soil physical and chemical properties than NPK only. Thus, the study showed that although the combined 100 % NPK and FYM application had higher productivity of the maize–wheat system, the same is as remunerative as 50 % NPK + FYM, if the cost of FYM was considered. However, depending upon the resource availability, farmers can also apply Kudzu, maize stalk and wheat straw annually along with adjusted dose of NPK to a crop and full dose of NPK to the other crop as the alternate options.     

Physiological Indices,Phenological Characteristics and Trait Evaluation of Canola Genotypes Response to Different Planting Dates

To manage planting date based on optimal compatibility to the environmental condition a split plot experiment based Randomized Complete Block Design with three replications was carried out. Four planting dates (November 6th and 21st, December 6th and 21st) in main plots and four genotypes (Hyola401, PP401, RGS003 and Option500) in subplots were studied. According to analysis of variance results, grain yield, yield components and biological yield were significantly affected by planting date, genotypes and interaction effect. The first planting date (November 6th) had maximum grain yield (2611.6 t ha^?1) and after it another planting date showed decrease in amount (13.74, 31.36 and 41.97 % respectively). First planting date was superior in physiological index as compared to the other planting dates. Hyola401 hybrid, due to the fact that it had a higher leaf area index (3.51), total dry matter (1248.91 g m^?2), crop growth rate (21 g m^?2 day^?1), net assimilation rate (7 g m^?2 day^?1), relative growth rate (0.064 g g^?1 day^?1) and maximum grain yield, was seen to be the most adaptable genotype. Hyola401 hybrid at first planting date germinated in shortest time (5.8 day) had the highest flowering duration (24.0 day) and long days to ripening (154.0 day). Finally according to the results of the present work, sowing of Hyola401 hybrid on 6th November was recommended as suitable planting date.     

Effect of In situ Recycling of Sugarcane Crop Residues on Soil Enzyme Activities Under Soybean–Maize System

An investigation was carried out by conducting a field experiment at the farm of the Mahatma Phule Krishi Vidyapeeth (MPKV), Rahuri. The significant grain yield of soybean (37.5 q ha^?1) and maize (49 q ha^?1) were observed in the treatment receiving 100 % recommended doses of Nitrogen, Phosphorus and Potassium (NPK) + in situ compost of crop residues, pressmud compost (T₆). After harvest of maize dehydrogenase activity, acid phosphatase, β-glucosidase and urease were significantly improved in T₇ treatment as compared to other treatments. However, fluorescein diacetate activity and alkaline phosphatase were significantly greater in T₆ treatment in post-harvest soil samples of maize. In the post-harvest soil of maize the bacterial and actinomycetes population were greater in the treatment receiving in situ decomposition of sugarcane crop residues + 100 % recommended dose of NPK (T₃). The fungal population after harvest of maize was found maximum in treatment T₇. The total organic carbon was significantly correlated with dehydrogenase (r = 0.65, P < 0.01), fluorescein diacetate (r = 0.71, P < 0.01), acid phosphatase (r = 0.66, P < 0.01), β-glucosidase (r = 0.65, P < 0.01), and urease (r = 0.57, P < 0.01). There was a significant correlation (r = 0.77, P < 0.01) between TOC and soybean yield, and between total organic carbon and maize yield (r = 0.98, P < 0.01). The result suggest that in situ recycling of sugarcane crop residues and the industrial wastes with suitable interventions like use of bioinoculum, phosphatic fertilizer and urea may help for improving better crop productivity and soil biological activities.     

Study of Optimum Time Span for Distinguishing Rumex spinosus in Wheat Crop Through Spectral Reflectance Characteristics

Using the inherent spatial and temporal variability within a field to manage farm operations is called precision agriculture. This is a site-specific approach which can reduce input costs and results in higher crop productivity, profitability and lesser environmental pollution. Remote sensing provides a means for the development of weed maps by detecting the location of weeds within an agricultural field, so that site-specific/need based herbicide can be applied. Reductions in herbicide use as a result of this practice reduce management costs for farmers and promote environmental friendliness. The results revealed a decreasing trend in the number of tillers, effective tillers, number of grains per ear, 1,000-grain weight and grain yield of wheat with increasing population densities of Rumex spinosus (from 3 to 12 plants m^?2). Highest grain yield of wheat (5.75 tonnes ha^?1) was recorded under solid stand of wheat and lowest grain yield was recorded in treatments having 12 plants of R. spinosus. Higher radiance ratio and NDVI values were recorded in solid stand or pure wheat treatment and minimum under solid weed plots. It was observed that by using radiance ratio and NDVI, pure wheat can be distinguished from pure populations of R. spinosus after 30 DAS. It remains distinguished upto 120 DAS. Different levels of Rumex populations can be discriminated amongst themselves from 60 DAS onwards.     

Wood properties of Eucalyptus globulus at three sites in Western Australia: effects of fertiliser and plantation stocking

Wood properties of 10-year-old trees in Eucalyptus globulus plantations at three sites in Western Australia were examined. Silvicultural treatments applied at age two years were stocking (unthinned, 1250 stems ha^–1; thinned to 600 stems ha^–1 or 300 stems ha^–1) and nitrogen fertiliser application (0 or 250 kg ha^–1 elemental nitrogen) in factorial combination. The three sites differed markedly in their annual rainfall (620–1100 mm), open-pan evaporation and soil water-holding capacity. Wood cores were collected at breast height from a total of 263 trees (~15 trees for each site-by-treatment combination), and radial samples prepared for analysis by SilviScan to produce radial profiles of air-dry density and microfibril angle (MFA) and modulus of elasticity (MOE), and by radial near infrared (NIR) surface scanning to produce radial profiles of NIR-predicted Kraft pulp yield (KPY) and cellulose content (CC). Sampling interval was 0.025 mm for density and 5 mm for the other properties. For wood property mean values (i.e. wood property averages of each pith-to-cambium sample), sites differed significantly only in air-dry density. The Boyup Brook site, which had low annual rainfall, the lowest climate wetness index and soil water-storage capacity and the slowest diameter growth, had the highest mean wood density (648 kg m^–3), while Scott River, with the highest rainfall, had mean density that was 10% lower. The Wellstead site (low rainfall but highest soil water-storage capacity) was intermediate for density. The only other significant differences for mean wood properties were caused by fertiliser addition, which reduced NIR-predicted KPY from 54.6% (without fertiliser) to 54.1% and predicted CC from 43.7% to 43.1%. Clear radial trends were evident for all wood properties. Density, MOE, KPY and CC all increased from pith to the cambium, while MFA declined. From the innermost (pith) 10% to the outermost (cambial) 10% of the radius, density increased on average by 21%, MOE by 103%, KPY by 9% and cellulose by 11%, while MFA declined by 47%. NIR calibrations developed using the SilviScan and NIR spectral data explained 71% of variance in MOE for an independent set of radial wood samples of E. globulus from Victoria, but less than 50% of variance for density and MFA. Implications for paper pulp and veneer manufacture are briefly considered.     

Managing wood production from small grower acacia hybrid plantations on eroded soils in central Vietnam

An experiment in a second rotation acacia hybrid (Acacia mangium × A. auriculiformis) clonal plantation in central Vietnam examined factors determining total wood production and its apportionment to sawlog and pulpwood. Growth and stand characteristics were compared with those in nearby plantations owned by small growers. The experimental site was on sloping land damaged and eroded by war and previous land use. The soil was shallow, with 20–30% laterised stones by volume and had lost part of the A horizon. Mean annual increment (MAI, in standing merchantable volume over bark) of the first rotation at age 8.8 years was 17 m³ ha^?1 y^?1. In the second rotation at age 7.6 years it was 20 m³ ha^?1 y^?1. Application of P fertiliser at three rates ranging from 14 to 86 kg ha^?1 increased stem diameter over the second rotation although stand volume response to P was not significant by rotation end. Potassium (14 kg ha^?1) gave no growth response. Growth rate was similar under weed control by herbicide and manual means. MAI increased progressively from 16.5 m³ ha^?1 y^?1 at the hilltop to 25.0 m³ ha^?1 y^?1 at the lowest part of the experiment; slope position influenced growth more than management practices. Key soil properties, pH, N, Bray-1 P and organic C were maintained from the first to the second rotation. With simple management practices including conservation of site organic matter and early stand management, appropriate for local small growers, the second rotation yielded 46% of harvested volume as sawlogs and the balance as pulpwood. Although small growers achieved similar growth rates, their current management regime does not yield sawlogs. They can influence the log categories produced and stand value through changes to stocking rate, stand management and rotation age.     

Long-term estimates of live above-ground tree carbon stocks and net change in managed uneven-aged mixed species forests of sub-tropical Queensland,Australia

Estimates of carbon stocks and their annual change for extensive Australian sub-tropical forests are based on indirect estimates or on data derived from temperate forests. We estimated live above-ground tree carbon (LAC) stocks at landscape level from 355?000 measurements of 94?127 tree stems from 604 permanently monitored plots representing 2.6 million ha of managed uneven-aged mixed-species native forests in sub-tropical Queensland. These plots were established between 1936 and 1998 and re-measured every 2 to 10 years up to 2011. Landscapes were represented by 16 broad vegetation groups growing across a mean annual rainfall range of 500 to 2000 mm. Landscape-mean LAC stocks varied from 20.8 ± 4.3 t C ha^?1 in inland eucalypt woodlands to 146.4 ± 11.1 t C ha^?1 in coastal wet tall open forests. Landscape maximum LAC stock, defined as the mean of maximum LAC stocks over the entire measurement history for a specified landscape under prevailing environmental conditions and disturbance regimes, including sustainable forest management, ranged from 34.0 ± 7.2 t C ha^?1 in inland eucalypt woodlands to 154.9 ± 19.4 t C ha^?1 in coastal wet tall open forests. Annual live above-ground net carbon flux (C-flux) across all forests types ranged from 0.46 to 2.92 t C ha^?1 y^?1 with an overall mean of 0.95 t C ha^?1 y^?1 (n = 2067). Comparison of our results with Intergovernmental Panel on Climate Change (IPCC) estimates shows that in all cases, except for the sub-tropical steppe, the IPCC over-estimated stocks by between 13% and 34%. Conversely, the IPCC estimated C-fluxes were between 14% and 40% less than the Queensland estimates. These results extend statistically valid estimates of landscape LAC stocks and fluxes to the sub-tropical regions of Australia.     

Estimating the vertical distribution of chlorophyll in winter wheat based on multi-angle hyperspectral data

ABSTRACT

Chlorophyll plays an important role in crop photosynthesis, which is closely related to nitrogen (N). N deficiency first occurs in the lower leaves, but the spectral detection of the lower layer is insufficient due to leaf shading. The aim of this paper was to investigate the feasibility of estimating the chlorophyll content of leaves (LCC) and the vertical distribution of LCC in wheat using multi-angle hyperspectral data. Three winter wheat layers were divided, and the multi-angle hyperspectral data of the different layers were obtained by removing the leaves from the lower layer to the top layer. The multi-angle vegetation index and LCC linear models were established, and the estimated model based on nadir view angle (i.e., conventional observation angle) was compared. Results show that (1) the best observation angle for the first layer, the second layer, and the third layer are 60°, 60°, 50°, respectively. (2) The accuracy of multi-angle-based estimation models (R² = 0.87, RMSE = 2.86 μg cm^?2) are higher than nadir-based ones (R² = 0.72, RMSE = 4.24 μg cm^?2). This study proved that vertical distribution has a positive influence on the estimation results, and multi-angle hyperspectral data could be promising in improving estimation accuracy.     

Biomass for aviation fuel production in the Fitzroy Basin,Queensland: a preliminary assessment of native and plantation forest potential

This scoping study assesses the contribution that woody biomass could make to feedstock supply for an aviation biofuel industry in Queensland. The inland 600–900 mm rainfall zone, including the Fitzroy Basin region, is identified as an area that is particularly worthy of closer study as it has potential for supply of woody biomass from existing native regrowth (brigalow and other species) as well as from new plantings. New analyses carried out for this study of Corymbia citriodora subsp. variegata trials suggest biomass plantings could produce harvestable yield of aboveground dry mass of about 85 t ha^?1 over a 10-year rotation at relatively low-rainfall (600–750 mm mean annual precipitation) sites and about 115 t ha^?1 at medium-rainfall (750–900 mm) sites. Estimates of productivity for native regrowth suggest potential productivity should be around 40 t ha^?1 during the initial decade after clearing when systems are managed for bioenergy rather than grazing. In this paper, potential production systems are described, and sustainability issues are briefly considered. It is concluded that more detailed studies focused particularly on biomass production would be worthwhile, and further research requirements are briefly discussed.     

Effects of Tillage and Residue Management Practices on Soil and Root Parameters in Soybean (<Emphasis Type="Italic">Glycine max</Emphasis>)–Wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis>) Cropping System

A field study was conducted during 2009–2011 to investigate the effect of tillage, crop establishment and residue management practices on soil and root parameters in soybean-wheat cropping system. The experiment was conducted with 4 main plot treatments of tillage and crop establishment techniques as conventional tillage-flat (CT-F), zero tillage-flat (ZT-F), conventional tillage-bed (CT-B) and zero tillage-bed (ZT-B); and 4 sub plot treatments of residue application as control, wheat residue (3 t ha^?1), soybean residue (3 t ha^?1) and soybean + wheat residue (3 t ha^?1 each). The infiltration rate was significantly higher with ZT-F (1.22 cm h^?1) and wheat + soybean residue application (1.16 cm h^?1). ZT-F and ZT-B recorded higher mean weight diameter and geometric mean diameter at 0–10 cm than that of CT-F and CT-B. The percentage of micro-aggregate was higher with CT-F and CT-B at all depths while the macro-aggregate was high with ZT-F and ZT-B up to 30 cm soil depth. The microbial biomass carbon in ZT-F and ZT-B was 216.3 and 214.6 µg g^?1 of soil, respectively which was significantly higher than that of CT-F and CT-B. The wheat + soybean residue application recorded 19.6 % higher MBC than the control. Among the tillage treatments, ZT-F performed well with regard to root length density as 2.38 and 1.11 cm cm^?3, root surface area as 0.67 and 0.36 cm² cm^?3, root volume density as 19.22 and 8.26 × 10^?3 cm³ cm^?3 and average root diameter as 1.06 and 0.81 mm by soybean and wheat, respectively. Similarly, wheat + soybean residue also performed better than the no residue treatment.     

Productivity,Water Use and Energy Profitability of Staggered Maize–Legume Intercropping in the Eastern Himalayan Region of India

In eastern Himalayan region, growers cultivate many crops per unit area without following definite row proportions which resulted in lower productivity. Use of recent modern technologies in undulated topography is not feasible. Therefore, locally available resources were utilized for better water use, higher productivity and improved energy profitability in the maize–legume intercropping system. The studies were conducted at ICAR Research Complex for NEH Region, Basar, Arunachal Pradesh during the years 2010 and 2011. Maize, soybean and groundnut were planted solitary, and soybean and groundnut were intercropped with maize at 1:1, 1:2 and 1:5 row proportions. The maize grain yield was highest with solitary maize, but, intercrop yield was improved with higher row proportions. Maize equivalent yield and per day productivity were highest with 1:5 of maize–groundnut. Higher row proportion of legumes improved the water use but it was highest with solitary soybean (911.1 mm). The improvement of water use efficiency by 83.2 %, harvest monetary benefit by 87.5 %, benefit cost ratio by 92.3 % and energy productivity by 38.5 % with 1:5 of maize–groundnut over solitary maize. The energy input and output efficiency was higher with 1:2 of maize–groundnut, but output and net energy were superior under 1:2 of maize–soybean. The soil moisture content and solar radiation interception were 24.1 and 37.8 % which were improved with solitary soybean over solitary maize. Intercropping practices tender numerous advantages but improved understanding of the ecological mechanisms associated with intended row arrangement, including additional advantage of crop yield and water use, are needed to augment the benefit.     

Quantitative and qualitative assessment of timber harvesting residues: a case study of a balsa plantation in Papua New Guinea

The quantity and quality of the harvesting residues in a balsa plantation in East New Britain Province of Papua New Guinea are reported in this paper. The plantation was harvested manually with a chainsaw and manpower to extract the industrial wood at age 6 years. A modified standard harvesting residue assessment method using plots on line transects was applied. The total weight of the harvest residues remaining on the site after wood extraction was 211.7 t_GREEN ha^?1 (tonnes (green) per hectare). The major component was un-merchantable stem wood (121.3 t_GREEN ha^?1; 57.3%), followed by bark (59.3 t_GREEN ha^?1; 28.0%). This level of harvest residue was relatively greater than that reported in other studies, reflecting the combination of the log specification applied and the nature of the stem defects in balsa trees. The level of residues indicates the possibility of additional woody material recovery for bioenergy after consideration of sustainability issues.

The average moisture content of the wood components of the residues was determined over two days. The average moisture content on the first day after harvesting was 50%, falling in the following day to about 48%. The abundance of five elements in the harvest residues was estimated using data from a single sample tree; of the elements assessed potassium was the most abundant while calcium was the least.