Influence of nitrogen fertiliser application and timing on greenhouse gas emissions from a lychee (Litchi chinensis) orchard in humid subtropical Australia

Nitrous oxide emissions from intensive, fertilised agricultural systems have been identified as significant contributors to both Australia's and the global greenhouse gas (GHG) budget. This is expected to increase as rates of agriculture intensification and land use change accelerate to support population growth and food production. Limited data exists on N2O trace gas fluxes from subtropical or tropical tree cropping soils critical for the development of effective mitigation strategies.This study aimed to quantify GHG emissions over two consecutive years (March 2007 to March 2009) from a 30 year (lychee) orchard in the humid subtropical region of Australia. GHG fluxes were measured using a combination of high temporal resolution automated sampling and manually sampled chambers. No fertiliser was added to the plots during the 2007 measurement season. A split application of nitrogen fertiliser (urea) was added at the rate of 265kgNha-1 during the autumn and spring of 2008. Emissions of N2O were influenced by rainfall events and seasonal temperatures during 2007 and the fertilisation events in 2008. Annual N2O emissions from the lychee canopy increased from 1.7kgN2O-Nha-1yr-1 for 2007, to 7.6kgN2O-Nha-1yr-1 following fertiliser application in 2008. This represented an emission factor of 1.56%, corrected for background emissions. The timing of the split application was found to be critical to N2O emissions, with over twice as much lost following an application in spring (2.44%) compared to autumn (EF: 1.10%). This research suggests that avoiding fertiliser application during the hot and moist spring/summer period can reduce N2O losses without compromising yields.

Influence of historic land use change on the biosphere-atmosphere-exchange of C and N trace gases in the humid, subtropical region of Queensland

Increases in atmospheric concentrations of the greenhouse gases (GHGs) carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) due to human activities have been linked to climate change. GHG emissions from land use change and agriculture have been identified as significant contributors to both Australia’s and the global GHG budget. This is expected to increase over the coming decades as rates of agriculture intensification and land use change accelerate to support population growth and food production. Limited data exists on CO2, CH4 and N2O trace gas fluxes from subtropical or tropical soils and land uses. To develop effective mitigation strategies a full global warming potential (GWP) accounting methodology is required that includes emissions of the three primary greenhouse gases. Mitigation strategies that focus on one gas only can inadvertently increase emissions of another. For this reason, detailed inventories of GHGs from soils and vegetation under individual land uses are urgently required for subtropical Australia. This study aimed to quantify GHG emissions over two consecutive years from three major land uses; a well-established, unfertilized subtropical grass-legume pasture, a 30 year (lychee) orchard and a remnant subtropical Gallery rainforest, all located near Mooloolah, Queensland. GHG fluxes were measured using a combination of high resolution automated sampling, coarser spatial manual sampling and laboratory incubations. Comparison between the land uses revealed that land use change can have a substantial impact on the GWP on a landscape long after the deforestation event. The conversion of rainforest to agricultural land resulted in as much as a 17 fold increase in GWP, from 251 kg CO2 eq. ha-1 yr-1 in the rainforest to 889 kg CO2 eq. ha-1 yr-1 in the pasture to 2538 kg CO2 eq. ha-1 yr-1 in the lychee plantation. This increase resulted from altered N cycling and a reduction in the aerobic capacity of the soil in the pasture and lychee systems, enhancing denitrification and nitrification events, and reducing atmospheric CH4 uptake in the soil. High infiltration, drainage and subsequent soil aeration under the rainforest limited N2O loss, as well as promoting CH4 uptake of 11.2 g CH4-C ha-1 day-1. This was among the highest reported for rainforest systems, indicating that aerated subtropical rainforests can act as substantial sink of CH4. Interannual climatic variation resulted in significantly higher N2O emission from the pasture during 2008 (5.7 g N2O-N ha day) compared to 2007 (3.9 g N2O-N ha day), despite receiving nearly 500 mm less rainfall. Nitrous oxide emissions from the pasture were highest during the summer months and were highly episodic, related more to the magnitude and distribution of rain events rather than soil moisture alone. Mean N2O emissions from the lychee plantation increased from an average of 4.0 g N2O-N ha-1 day-1, to 19.8 g N2O-N ha-1 day-1 following a split application of N fertilizer (560 kg N ha-1, equivalent to 1 kg N tree-1). The timing of the split application was found to be critical to N2O emissions, with over twice as much lost following an application in spring (emission factor (EF): 1.79%) compared to autumn (EF: 0.91%). This was attributed to the hot and moist climatic conditions and a reduction in plant N uptake during the spring creating conditions conducive to N2O loss. These findings demonstrate that land use change in subtropical Australia can be a significant source of GHGs. Moreover, the study shows that modifying the timing of fertilizer application can be an efficient way of reducing GHG emissions from subtropical horticulture.

Efficacy and Residue Comparisons between Two Slow-release Formulations of Fluridone

Residue profiles and efficacy of Avast and Sonar, two slow release pellet formulations of fluridone {1-methyl-3-phenyl-5- [3-(trifluoromethyl)phenly]-4(1H)-pyridinone}, were compared in outdoor tanks. Hydrilla (Hydrilla verticillata (L.f.) Royle) and southern naiad (Najas guadalupensis (Sprengel) Magnus) were treated with a split application of 6, 12, 18 and 24 μg/l a.i. fluridone and the concentrations of both formulations compared over a 134-day period. Both pellet formulations exhibited very similar residues over time for each respective treatment, resulted in peak concentrations of fluridone 40 to 50 days after application, and effectively and similarly controlled southern naiad and hydrilla at all rates tested by 92 days after initial application. (PDF contains 3 pages.)

Effect of N fertilizer on the productivity and nutritive values of perennial grass mixtures in the alpine region of Qinghai-Tibetan Plateau, China

A study was conducted on grass mixtures that included smooth bromegrass (SB) + drooping wild ryegrass (DW), smooth bromegrass + Siberian wild ryegrass (SW) + crested wheatgrass (CW) and smooth bromegrass + Siberian wild ryegrass + drooping wild ryegrass + crested wheatgrass in the alpine region of Qinghai-Tibetan Plateau. The study was conducted from 1998 to 2000 to investigate the effects of N application rates and growing year on herbage dry matter (DM) yield and nutritive values. Herbage DM production increased linearly with N application rates. The effect of N application on DM yields was greater (P < 0.05) in the 2nd and 3rd production years than in the establishment year. Dry matter yields of SB + SW + CW and SB + SW + DW + CW can reach as high as 15 000 kg ha(-1) at 345 kg ha(-1) N rate in the 3rd growing year. With increased N application rates, crude protein (CP) contents and 48 h in sacco DM degradability of grasses increased (P < 0.05). No effect (P > 0.05) of N application was detected on organic matter (OM) and acid detergent fibre (ADF) concentration. It can be concluded that for increased biomass production in the alpine region of the Qinghai-Tibetan Plateau, a minimum of 345 kg N ha(-1) should be applied to grass stands in three split application of 115 kg N ha(-1), in early June, early July and late July

Parcelamento e largura da faixa de aplicação da uréia na recuperação do nitrogênio pela planta de milho

Com o objetivo de estudar o parcelamento e a largura da faixa de aplicação como meios para aumentar a recuperação pelo milho do nitrogênio da uréia aplicada em superfície, foi conduzido no ano agrícola 93/94, em um Latossolo Vermelho Escuro, em condições de campo, um experimento delineado em blocos ao acaso, com cinco repetições. Sete tratamentos foram utilizados: testemunha (sem N em cobertura); aplicação de N parcelada (50 kg ha-1 de N aos 38 dias após semeadura - d.a.s e 50 kg ha-1 de N aos 60 d.a.s.) para faixas de 10, 20 e 40 cm; aplicação de N (100 kg ha-1 de N aos 38 d.a.s.) para faixas de 10 e 40 cm e, aplicação de N parcelada (50 kg de N/ha aos 38 d.a.s. e 50 kg ha-1 de N aos 60 d.a.s.) para faixa de 20 cm de largura, neste caso, uréia granulada. A aplicação de uréia parcelada em cobertura, em faixas de 10, 20 e 40 cm de largura, não afetaram a massa de matéria seca, o conteúdo, a quantidade e a recuperação do N pela planta de milho. A recuperação de N pela planta de milho foi maior para a aplicação de 220 kg ha-1 de uréia em uma única aplicação em faixas de 10cm de largura em relação a de 40 cm. O parcelamento da uréia aumentou os valores de massa seca, conteúdo, quantidade e recuperação do N na planta de milho em relação a aplicação em uma única vez.

Modos de aplicação de regulador vegetal no algodoeiro, cultivar IAC-22, em diferentes densidades populacionais e níveis de nitrogênio em cobertura

Este trabalho foi desenvolvido nos anos agrícolas de 1996/97, 1997/98, 1998/99 e 1999/00, em experimentos de campo nas localidades de Ribeirão Preto, Tietê, Guaíra, Campinas e Ilha Solteira, no Estado de São Paulo. O delineamento experimental empregado foi o de blocos ao acaso com doze tratamentos arranjados em um esquema fatorial 3 x 2 x 2, visando estudar densidade de plantas (6 ; 10 e 14 plantas por metro); doses de nitrogênio em cobertura (40 e 60 kg.ha-1 de N) e modos de aplicação de regulador vegetal, com aplicação única, no início do florescimento ou parcelada em 4 vezes, desde o desbaste. O sistema de aplicação parcelada propiciou altura média de planta inferior e massa média de capulhos superior àquele obtido com a aplicação única do regulador. A aplicação da maior dose de N implicou obtenção dos maiores valores de N foliar e produtividade de algodão em caroço, bem como menor porcentagem de fibra. O aumento da densidade de plantas de 6 para 10 e 14 plantas por metro, ocasionou redução da porcentagem de fibra e da massa de capulhos.

Aplicação de nitrogênio no solo e pulverização foliar com ácido giberélico e uréia em Setaria anceps Stapf cv. Kazungula

O objetivo do experimento foi verificar o efeito do nitrogénio no solo, parcelado de diferentes formas e aplicado durante o período de "verão", combinado com pulverização foliar de ureia e/ou ácido giberélico, sobre a produção e qualidade de Setaria anceps Stapf cv. Kazungula. O nitrogênio (60 kg/ha/ano) foi aplicado segundo quatro formas de parcelamento: Testemunha (sem nitrogênio), N20M40 (20 kg/ha de N em novembro + 40 kg/ha de N em março), N30M30 (30 kg/ha de N em novembro + 30 kg/ha de N em março), F20M40 (20 kg/ha de N em fevereiro + 40 kg/ha de N em março). No início do período de "inverno" foram aplicados os quatro tipos de pulverizações foliares: Testemunha (sem ácido giberélico ou uréia), uréia a 2%, ácido giberélico a 50 ppm e uréia a 2% + ácido giberélico a 50 ppm. Os resultados revelaram que o parcelamento do nitrogénio no solo não influiu no aumento da produção de matéria seca do capim setária no período de "verão", apesar de proporcionar um incremento da mesma no corte de "inverno". Observou-se, ainda, uma boa distribuição da produção de matéria seca entre "verão" e "inverno", apresentando essa última estação 34,52% da produção total anual, em média. Os diferentes tipos de pulverização não influíram significativamente sobre a produção de matéria seca e a composição química bromatológica da forrageira no período de "inverno".

Desenvolvimento e produtividade do algodoeiro em função de espaçamentos e aplicação de regulador de crescimento

Currently, the cultivation of the cotton plant is based on a scale production model, characterized by high yields and intensive use of fertilizers, agrochemicals and mechanization. The objective of this study was to evaluate the influence of different row spacings on cotton crops, with or without growth regulator, and their effects in crop development and yield. The experimental design was in completely randomized blocks, in a 3x3 factorial scheme with 4 replications, using three row spacings: 0.45, 0.70 and 0.90 m. Three growth regulator conditions were tested: a) application split into four stages, b) single application at 70 d.a.e, and c) no regulator application. The project was conducted in the city of Selviria, Mato Grosso do Sul state, in November 2005. It was verified that the application of growth regulator is efficient in the limitation of plant height. The highest yield and boll mass was found in the split application of the regulator. The number of bolls and reproductive branches per plant was higher in the wider row spacings.

Utilização do cloreto de clorocolina no controle do bicudo-do-algodoeiro

The objective of the present work was to evaluate the effect of the growth regulator chlorocholine chloride (CCC) in the control of the boll weevil (Anthonomus grandis Boheman) on cotton ( Gossypium hirsutum L. ). The experiment was conducted at the Experimental Farm of the Faculdade de Ciências Agrárias e Veterinárias (UNESP), Jaboticabal Campus, State of São Paulo, Brazil, during the 1988/1989 growing season. The experimental design used was the latin square. The chlorocholine chloride was sprayed on the cv IAC-19 cotton plants 70 days after emergence in the doses of 0, 25, 50, and 100 g/ha in a single application as well as 25 g/ha + 25 g/ha in two applications. The second application was 15 days after the first. There was no significant differences on cotton yield. Although the split application as well as the single application of 25 g/ha increased yield in 11.6% and 11.5%, respectively.These same treatments also increased earliness. After the last hand harvest the number of immature cotton bolls left in the field was 64.5% lower in the plots treated with chlorocholine chloride. Despite the higher earliness and the reduction of the number of immature cotton bolls, the chlorocholine chloride treatments were not sufficient to induce an effective aid in the boll weevil control but indicates a possibility of using growth regulators in the cotton crop as an auxilary strategy in integrate pest management programs.

Fontes e parcelamento do nitrogênio em cobertura, na cultura do milho sob plantio direto

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Manejo da aplicação de regulador de crescimento via sementes em algodoeiro

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Desenvolvimento e produção do algodoeiro em função de espaçamentos e aplicação de regulador de crescimento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Resposta do feijoeiro ao preparo do solo, manejo de água e parcelamento da adubação nitrogenada

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Parcelamento da adubação nitrogenada em cobertura no feijoeiro em sucessão ao milho e Urochloa ruziziensis em sistemas plantio direto

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Nitrogen fertilization management in no-tillage maize with different winter crops

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)