Recovery in plants and soils of 15N applied as subsurface bands of urea to sugarcane

1996 ◽  
Vol 47 (3) ◽  
pp. 355 ◽  
Author(s):  
I Vallis ◽  
VR Catchpoole ◽  
RM Hughes ◽  
RJK Myers ◽  
DR Ridge ◽  
...  
Keyword(s):  
New South ◽  
N Uptake ◽  
New South Wales ◽  
Cultural Practice ◽  
Internal Drainage ◽  
Total Recovery ◽  
Plant System ◽  
South Wales ◽  
Crop N Uptake ◽  
Crop Maturity

The recovery of fertiliser N by sugarcane crops is low in comparison with most other field crops. Application of urea in subsurface bands instead of by broadcasting can greatly reduce loss of fertiliser N due to ammonia volatilisation, but the fertiliser N is still susceptible to loss from leaching or denitrification, which could be affected by soil internal drainage, trash management, or tillage practice. The recovery of fertiliser N in crops and soil from 15N-labelled urea applied as subsurface bands was measured in ratoon crops in southern Queensland and northern New South Wales. Two soil types, with contrasting internal drainage, were used in each region. In Queensland, the cultural practice was either trash burnt with inter-row cultivation or trash retained on the surface ('trash blanket') with no cultivation. In northern New South Wales, where the trash was burnt prior to harvest, the practice was either inter-row cultivation or zero tillage. Crop recovery of fertiliser N was nearly always in the range 20-40% of the amount applied. Residual fertiliser N in the soil at crop maturity ranged from 13 to 42% (average 26%). Total recovery of fertiliser N in the soil-plant system ranged from 35 to 76% (average 52%) at 6 months after application, and from 35 to 96% (average 56%) at crop maturity. Urea fertiliser supplied only 20-40% of the crop N uptake in a given season. Neither crop recovery nor loss of fertiliser N from the soil-plant system were related to the soil type or cultural practice used, indicating that compensatory effects occurred.

Effect of split nitrogen applications on the yield and protein content of dryland wheat in northern New South Wales

1991 ◽  
Vol 31 (1) ◽  
pp. 85 ◽  
Author(s):  
AD Doyle ◽  
RA Shapland
Keyword(s):  
Grain Yield ◽  
New South ◽  
N Uptake ◽  
New South Wales ◽  
Dry Weight ◽  
Yield Response ◽  
Equivalent Amount ◽  
N Application ◽  
South Wales ◽  
Yield Responses

Experiments were conducted with dryland wheat on a nitrogen (N) deficient site near Gunnedah, northern New South Wales, in 1987 and 1988 to compare post-sowing foliar applications of N with urea drilled between the rows at sowing. Post-sowing N was applied at tillering, booting or at both stages at rates of 20 or 40 kg N/ha while presowing applications ranged from 0-106 kg N/ha. Above ground dry weight and N uptake increased with increasing N application at sowing. Post-sowing N application increased dry weight and N uptake, with generally greater increases in N uptake than in dry weight. Dry weight and N uptake for post-sowing N application were invariably less than when an equivalent amount of N had been applied at sowing. Grain yield was increased by the application of up to 106 kg N/ha at sowing in 1987 and up to 80 kg N/ha in 1988 when a greater degree of moisture stress during grain filling restricted yield responses. Post-sowing N increased grain yield, but the yield response was lower than for the application of an equivalent amount of N at sowing. Grain yield responses were lower when N was applied at booting rather than tillering. Yield responses over the 2 years were 0.35-0.39 t/ha and 0.44-0.68 t/ha for 20 and 40 kg N/ha, respectively, applied at tillering and 0.26-0.4 t/ha and 0.26-0.48 t/ha for N application at booting. Post-sowing N application increased grain protein, with greater increases for booting than for tillering applications. There was an apparent recovery in the grain of 48-56% of N applied at sowing, but only 25-48% of N applied post-sowing.

Effects of simulated seedling defoliation on growth and yield of cotton in southern New South Wales

2018 ◽  
Vol 69 (9) ◽  
pp. 915 ◽  
Author(s):  
Jianhua Mo ◽  
Sandra McDougall ◽  
Sarah Beaumont ◽  
Scott Munro ◽  
Mark M. Stevens
Keyword(s):  
Leaf Area ◽  
New South ◽  
New South Wales ◽  
Thrips Tabaci ◽  
Growth And Yield ◽  
Growth Stages ◽  
Early Season ◽  
South Wales ◽  
Four Seasons ◽  
Crop Maturity

Early-season leaf loss due to damage by thrips (Thysanoptera: Thripidae) is considered an important issue by Australian cotton growers. To understand the potential impact of early-season leaf loss in the southern region of New South Wales, we investigated the effects of artificial defoliation on cotton growth, maturity timing and lint yield over four seasons (2013–14 to 2016–17) in commercial cotton crops in the Riverina district. Four defoliation scenarios were investigated: (i) complete defoliation, 100% removal of all true leaves from all plants; (ii) partial defoliation by plant, 100% removal of all true leaves from 75% of plants; (iii) partial defoliation by leaf, removal of 75% of leaf area from all individual true leaves on all plants; and (iv) no defoliation. Defoliation was done by hand at the onset of the 2-, 4-, and 6-node growth stages. Defoliated plants were initially shorter than undefoliated (control) plants, but by ~100-days post seedling emergence, height differences were no longer statistically significant in two of the four seasons. Defoliation did not affect the total number of bolls shortly before harvest. However, complete defoliation delayed crop maturity by up to 18 days and partial defoliation by plant delayed crop maturity by up to 8 days. Because of the delays, fully defoliated plants often had fewer open bolls shortly before harvest and yielded significantly less than undefoliated plants in three of the four seasons. A laboratory experiment with caged cotton seedlings showed that weekly introductions of up to10 thrips per seedling (predominantly onion thrips (Thrips tabaci), the most abundant species on cotton in the region) caused significant clubbing in true leaves, but the total leaf area was not significantly reduced at the 6-node stage. Implications of the results for southern cotton integrated pest management are discussed.

Presowing nitrogen fertiliser management for aerial-sown rice on puddled soil

1994 ◽  
Vol 34 (7) ◽  
pp. 1013
Author(s):  
LM Kealey ◽  
E Humphreys ◽  
AS Black ◽  
WA Muirhead
Keyword(s):  
Grain Yield ◽  
New South ◽  
N Uptake ◽  
New South Wales ◽  
Application Rate ◽  
Available N ◽  
Soil Cultivation ◽  
South Wales ◽  
Application Depth ◽  
Puddled Soil

Presowing nitrogen (N) fertiliser management for aerial-sown rice was investigated for 2 soil cultivation methods, conventional cultivation and puddling, in the Coleambally Irrigation Area of New South Wales. Two N sources, urea and anhydrous ammonia (NH3, ColdFlo), were used. Urea was applied at 3 depths (0,7, 17 cm) and NH3 at 2 depths (7, 17 cm). These 5 treatments were compared with an unfertilised control and with a novel method of applying NH3 in the same operation as puddling. Urea was applied at 60 kg N/ha; the application rate of NH3 appeared to be higher than the intended rate of 60 kg N/ha. The site was responsive to N: agronomic efficiency of the urea-fertilised treatments averaged 39 kg grain yield increase/kg applied N. Dry matter yield, N uptake, and grain yield were similar on conventionally cultivated and puddled soil. There were no significant interactions between cultivation and N treatments in their effects on crop growth or N uptake. Application depth of fertiliser also had no significant effect on crop performance. Applying NH3 in the same operation as puddling was as effective as other methods of applying N, with the advantage of allowing soil preparation and fertiliser application to be completed in 1 pass. Urea labelled with 15N was applied at depths of 0, 5, and 15 cm to microplots at a rate of 60 kg N/ha. Recoveries of 15N in plants and soil were similar for both methods of soil cultivation and for different N application depths, consistent with results from the large plots described above. There was no interaction between soil cultivation and urea application depth treatments. Recovery of applied 14N averaged 32% in the plant shoots and 24% in the top 30 cm of the soil. Recoveries of 15N from presowing urea application have not previously been reported for aerial-sown rice in New South Wales. The results suggest that puddling can be readily integrated into the rice management system without changing current fertiliser practices. However, soil N uptake was very high, accounting for around 90% of the plant N uptake in the urea-fertilised treatments. Therefore, extrapolation of the results of the treatment comparisons to other sites with lower available N should only be done with caution.

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