Long-term growth responses to phosphatic fertilisers in a Pinus radiata plantation

The effects of phosphatic fertiliser on growth and nutrients in trials at different stages of stand development have been studied in second-rotation Pinus radiata plantation sites of Lidsdale State Forest, New South Wales. The sites were on phosphorus-deficient clay soils. High, early growth responses to phosphatic fertiliser occurred when applied to individual trees at the time of planting compared with slower initial growth when fertiliser was broadcast applied. There were long-term responses to broadcast treatments of phosphorus or nitrogen/phosphorus at time of planting, but it took several growing seasons for the trees to access the applied phosphorus. Later-age applications of phosphorus also gave significant responses with and without nitrogen and the level of response was related to the prior nutritional status of the stand. There were additional responses to high levels of nitrogen when the initial phosphorus deficiency was overcome. Application of phosphorus or nitrogen/phosphorus after thinning resulted in significant increases in growth. Combining trial results and assuming treatments were additive, it was concluded that productivity could be increased from 8 m³ ha^–1 y^–1 to about 16 m³ ha^–1 y^–1 over 24 years. The trials show there could be a range of nutritional management strategies where fertilisers are applied at various times in the rotation process and the appropriate one would be selected in terms of management objective, the cost and outcomes.     

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.     

Grade and value variations in Eucalyptus urophylla × E. grandis veneer due to variations in initial plantation spacings

Processing young, small-diameter eucalypt logs into veneer is a burgeoning industry across southern China. However, plantations supplying these logs are mostly managed on silvicultural regimes which are appropriate for pulpwood and little information is available on alternative regimes for eucalypt plantations with respect to veneer yields and quality. Log size along with a range of tree and log traits were assessed on 12-year-old eucalypts in six spacing treatments, ranging from 666 to 2?222 trees ha^?1, in a field trial in southern China. Logs harvested from these were rotary peeled for veneer; recovery percentages plus a range of quality and value traits were assessed on the outturn. Log volumes, small-end diameters and individual log values varied significantly between spacing treatments, but total veneer recoveries (as a percentage of log volume) and veneer values per unit volume did not. The spacing treatment providing the highest veneer value per unit area was that with the highest stocking; 2?222 trees ha^?1. Although the second logs (up from the butt log) had significantly lower average volume than butt logs, and they had significantly higher average value per unit volume because of higher average total veneer recovery (68.7%) compared with the butt logs (59.7%). A number of external log features were significantly correlated with veneer value per unit volume and total veneer-recovery percentage. In declining order of importance these were taper, sweep, number of visible epicormic stubs, number of bumps and visible branch stubs, and longitudinal growth strain in the outer-wood. Branch-related defects were the most important grade-limiting defect, limiting veneer sheet quality to D-grade for most sheets. Considerable improvement in veneer sheet quality may have been achieved by pruning either just before or after branch death. Mill-door prices for logs were calculated after accounting for processing costs obtained from the mill and averaged RMB774 m^?3 (about A$126 m^?3). Had the trees been pruned, simulations indicated that prices/values could be lifted by RMB60–128 m^?3 (A$10–21 m^?3) and RMB393–461 m^?3 (A$63–74 m^?3) for production of higher-quality structural veneer and appearance-grade face veneer, respectively. It appears feasible that improvement in mill-door log values is possible with production of appearance-grade face veneer, but this will require some improvement in log quality through silvicultural intervention with pruning. It will also require improvement in processing methods and reduction in the impact of log end-splitting on veneer quality.     

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.     

Nine year results from a Eucalyptus camaldulensis Dehnh. provenance trial in the Wellington catchment of Western Australia

Data for 20 provenances of Eucalyptus camaldulensis from the southern half of Australia including 14 provenances of variety camaldulensis and 6 provenances of variety obtusa were assessed for growth and form in the south west of Western Australia. Mean annual volume increment at age nine years was greater in variety camaldulensis (3.3 m³ ha^?1 yr^?1) than for variety obtusa (1.9 m³ ha^?1 yr^?1). No significant differences in forking or branching were found between the two varieties. Lake Albacutya (variety camaldulensis) was the most productive provenance yielding 5.3 m³ ha^?1 yr^?1 but was only average for form. Laura (variety camaldulensis) was the best all round performer yielding the third highest volume production (4.2 m³ ha^?1 yr^?1) and ranking in the top quartile for forking, branching and straightness. Within variety camaldulensis a weak correlation was found between height and mean annual rainfall, provenances from lower rainfall areas being more likely to produce taller trees. A trend for smaller numbers of persistent branches with decreasing rainfall was observed for the species as a whole.     

Growth response following variable espacement of 28-year-old Alpine Ash regeneration in New South Wales

Analysis of stand growth-response patterns have shown that small increases in sawlog volume resulted from thinning fast grown, fire regenerated alpine ash (Eucalyptus delegatensis R.T. Bak.) from below to a range of regular tree-spacings, at age 28 years. No significant correlation was found between basal area growth response and increased spacing for four treatments that ranged from 3.7 m to 7.3 m.

Rapid natural stocking-attrition occurred in both thinned and unthinned stands during the 31 post-thinning years of measurement. Maximum density diagrams indicated that these alpine ash stands were fully-stocked at lower densities than have been recorded for many other forest species. As a consequence of the propensity to self-thin, little additional stand growth was gained from the thinning treatments. The 150 trees ha^?1 with the largest diameters from all thinned stands averaged a basal area increase of only 0.59 mha^?1 over the 31 year period of measurement (<0.2 mha^?1 yr^?1), when compared with the equivalent stratum from an unthinned stand.

However, the small average nett growth response to spacing was not distributed evenly across the largest 150 trees ha^?1 dbhob. The 50 largest diameter trees ha^?1 in spaced stands showed a significant (α = 0.05) positive response, the trees ranked 51 to 100 showed no significant response and those trees ranked 101 to 150 showed a significant (α = 0.05) negative response when compared with the corresponding strata in the unthinned stand, over the same period.

Thus the overall result of stand spacing on the largest 150 trees ha^?1 was a widening of the stand diameter distribution and a small overall gain in the merchantable volume. For sites of higher quality, the basal area response was larger and predominantly accrued to the largest 50 trees ha^?1.     

Domestic timber harvesting affects wood quantities in Tasmanian dry eucalypt forests

Domestic fuelwood harvesters illegally reduced coarse (≥10-cm diameter) downed woody debris stocks in Tasmanian mature dry eucalypt forests, 27–34 m tall, by 96.9 m³ ha^?1 or 22.7 t ha^?1. There was no effect of domestic harvesting on quantities of dead trees or live trees. Few dead trees were encountered in natural (unharvested) sites. Domestic harvesters preferentially removed debris <70 cm in diameter, leaving domestically harvested sites with 40% less volume and biomass of downed woody debris than natural sites. Assuming domestic harvesting, at the measured intensity, extends 25 m into forests either side of the state forest road system that passes through the studied forest type, dead wood stocks in that forest type and tenure throughout the state have been reduced by 688?000 m³ or 161?000 t. Domestic harvesting potentially damages biodiversity values, diminishes habitat available for species dependent on fallen logs and reduces forest carbon stocks. Domestic harvesters are advised to obtain licences to collect fuelwood from areas with an appropriate forest practices plan.     

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.     

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.     

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.     

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.     

Merchantability of Pinus radiata in relation to previous land use

An integrated thinning operation was carried out in 21-year-old radiata pine stands in the central tablelands of New South Wales to examine the effect of previous land use and associated problems of poor tree form on recovery of merchantable timber. The areas thinned were contiguous sections of plantation which had different types of land use prior to plantation establishment; native forest, cleared grazing land (pasture) and cleared land initially grazed and subsequently cultivated and cropped (cultivated pasture). Total volumes of harvested trees (to 8 cm small end diameter) were estimated (assuming no poor tree form) from regressions relating volume to stem diameter. This estimate was compared with the actual volume of saw logs and pulp wood recovered on site and with merchantable yields predicted using a locally derived Forestry Commission equation.

On-site yields of saw logs plus pulp wood were 143 m³ ha^?1 from the ex-native forest site, 191 m³ ha^?1 from the ex-cultivated pasture site and 210 m³ ha^?1 from the ex-pasture site. This represented a total recovery of more than 90% of the total stem volume to 8 cm small end diameter from ex-native forest and ex-pasture trees compared with 73% from the ex-cultivated pasture trees.

Of the trees harvested, 45% from the ex-native forest site had stem defects compared with 65% from the ex-pasture site and 88% from the ex-cultivated pasture site. These defects reduced the average saw log volume per tree by at least 50% in trees greater than 35 cm DBHOB. In contrast, the yield of pulpwood was similar for deformed and non-deformed trees because some logs which did not meet saw log specifications were down-graded to pulp logs.     

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.     

Agronomic Performance and Nutrient Accumulation Behaviour in Groundnut-Cluster Bean Cropping System as Influenced by Irrigation Water Salinity

Varied levels of salinity in irrigation water remained a serious issue to shrink agricultural productivity in Saurashtra region of Gujarat. Groundnut, being a prominent crop in this zone, suffered to quite an extent due to induced salinity. In the present study, the authors have simulated a field condition where four different saline water of EC_iw of 0.5, 2.0, 4.0, 6.0 dS m^?1 were used for irrigation in groundnut (rainy/kharif)–cluster bean (summer) rotation. Both the crops were assessed by their respective growth and yield traits. A marked decrease was observed in seedling emergence, plant height, root length and pod yield at highest salinity, EC_iw 6.0 dS m^?1 whereas the same trend was noticed for plant height, dry weight of plant and final plant stand for cluster bean in the next season. However, pod yield of both the crops did not decrease up to EC_iw 2.0 dS m^?1. The ionic imbalance in different plant parts is another major impact of salinity. Na showed enhanced accumulation in plant parts where groundnut roots accumulated 42.0 and 75.4 % higher than shoots and kernels, respectively at highest EC_iw; while other nutrients (N, P, Ca, K) showed a declining effect with increasing salinity.     

Pinus pinaster and Pinus radiata survival,growth and form on 500–800 mm rainfall sites in southern NSW

Pinus radiata (GF27- and Guadalupe-based intraspecific hybrids) and Pinus pinaster were trialled to examine the potential for commercial deployment on three lower-rainfall sites within the 500–800 mm rainfall zone of New South Wales. All three ex-pasture sites were considered to be dry for P. radiata; two lower-elevation sites to the west of Gundagai being more challenging than a high-elevation site near Bombala. Cuttings and seedlings of genetically improved P. pinaster and P. radiata and a Guadalupe × routine cross seedlot of P. radiata were planted at three stockings (625, 1250 and 1850 stems per hectare (sph)) and were assessed for survival, growth (diameter at breast height, height, volume), form (straightness, malformations, branch size, branch angle) and number of commercially acceptable trees per hectare up to age 8 years.

Survival in P. pinaster didn’t decline after minor post-establishment mortality and was not affected by stocking or plant type. In contrast, survival in P. radiata continued to decline over time at 1250 and 1850 sph stockings at the two low-rainfall, low-elevation sites. Guadalupe-based seedlings had better survival than GF27 cuttings, but both present a high risk under dryland or drought conditions.

Site and stocking affected growth of the two species differently. P. radiata grew larger than P. pinaster at all sites. The combination of survival and growth resulted in site volume production that increased with stocking and site quality for P. pinaster. P. radiata exhibited a similar pattern but with reduced volume production at higher stockings on the high-quality Bombala site due to poor survival.

The form and branching of P. pinaster was better than that of P. radiata on all sites except the high-rainfall Oak Range. Form of P. pinaster cuttings was better than of seedlings. Form and branch size were improved by higher stockings and were worse on higher quality sites for both species. However, branch angle was better for P. radiata than for P. pinaster.

P. pinaster was reasonably productive on the best performing of the low-rainfall, lower-elevation sites. Given periods of very low rainfall since the establishment of these trials, the productivity of 6–7 m³ ha^–1 y^–1 at age 8 years at stocking of 1250–1875 suggests that 12–15 m^–3 ha^–1 y^–1 may be possible when mean annual increment (MAI) peaks at a later age. Although P. radiata growth rate was high, the poor survival and form of GF27, and to a lesser extent the Guadalupe cross, suggest it presents a high risk on these sites. Continued monitoring of the sites is therefore suggested. Further work could look at more drought-resistant taxa of P. radiata.     

Eucalyptus growth in relation to combined nitrogen and phosphorus fertiliser and soil chemistry in Tasmania

Two experiments were established to determine the early nutrient requirements for plantations of Eucalyptus globulus (Nabowla site) and E. nitens (Westfield site) in Tasmania, Australia. Nitrogen (N) and phosphorus (P) were broadcast together, 2 and 26 months after planting, at cumulative rates of up to 1200 kg N ha^?1 600 kg P ha^?1. Soil chemistry was characterised at each site in three profiles, and in all plots at the Westfield site. Nabowla has a relatively infertile, poorly structured soil, low in N and P, and receives about 800 mm of rainfall per annum. Growth was very poor without fertiliser, but trees responded rapidly and strongly to added NP. Stem volume increased directly with the rate of applied fertiliser, with no evidence that the response had peaked at the highest rate. Even at the highest rate of NP fertiliser, however, productivity was relatively low (mean annual increment about 15 m ha^?1 y^?1). Establishment of plantations on such sites is unlikely to be economically viable, with or without fertiliser, but fertile ex-pasture sites that are otherwise similar should be considered. Westfield has a relatively fertile, well-structured soil, and receives 1400–1500 mm of rainfall per annum. Response to NP fertiliser was delayed at this site, with first responses measured 33 months after planting. The response in stem volume was sigmoidal in relation to fertiliser rate, with a plateau at an application rate of 400 kg N ha^?1 and 200 kg P ha^?1. This rate of fertiliser is expected to increase mean annual increment from 20 (without fertiliser) to 25 m ha^?1 y^?1. Splitting applications of fertiliser at the highest rate did not alter the growth response.

Although high rates of N and P fertiliser may be required to maximise growth of eucalypt plantations in Tasmania on ex-forest sites, rates required during the first few years might be lower than those reported here if the timing and placement of fertiliser is optimised. Soil chemical analyses were indicative of N and P requirements, and about a third of the variation in growth across the Westfield site was accounted for by natural variability in initial concentrations of total P and exchangeable K in surface soil.     

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.     

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.     

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.     

Growth performance of selected taxa as candidate species for productive tree plantations in Borneo

ABSTRACT

The establishment of commercial tree plantations in Malaysian Borneo began with a progression of various species, including Pinus caribea, Acacia mangium, Gmelina arborea, Falcataria moluccana (formerly Albizia falcataria) and Eucalyptus deglupta. Ultimately, A. mangium, intended for the production of pulplogs, dominated the plantation landscape. However, recent widespread devastation of A. mangium by the Ceratocystis pathogen in Sabah has led to a shift in plantation species, which has also necessitated a review of downstream end products. This paper analyses growth data and estimates productivity for species in a taxa trial as well as a F. moluccana progeny trial in a single trial area in Sabah. A eucalyptus hybrid (Eucalyptus urophylla x Eucalyptus grandis (UG)), Eucalyptus pellita, F. moluccana, Acacia crassicarpa and A. mangium exhibited high productivity after three years, with an average mean annual increment of approximately 35 m³ ha^?1 y^?1 or better. Mean annual increment curves show that productivity declined slightly for the eucalypts and F. moluccana after three years. Acacia species experienced a sharper decline associated with disease-caused mortality, with A. mangium the most seriously affected. The mean basic density of the UG hybrid and F. moluccana was 560 kg m^?3 and 252 kg m^?3 at six and five years of age, respectively, and E. pellita had a mean basic density of 629 kg m^?3 at six years of age. The importance of growth and wood properties in the selection of species suitable for planted forest development in the wet tropics is discussed.