ABSTRACT
The current study aimed to evaluate the effects of different tillage systems on soil organic matter (SOM) contents and green corn yield (total ear weight) of an Argissolo Vermelho-Amarelo(Ultissol) in Coastal tablelands of northeast Brazil. The experiment was arranged as a strip plot design with three replications. Three tillage practices [conventional tillage (CT), minimum tillage (MT) and no-tillage (NT)] were laid out as a whole plot each (830 m²). Then, each plot was equally split into 12 experimental units (60 m²), distant 1 x 10 m from each other, where in four cover crops [pigeon pea (Cajanus cajan (L.) Millsp.), sunn hemp (Crotalaria juncea L.), beans (Phaseolus vulgaris) and peanut (Arachis hypogeae) were seedling previous to corn cultivation. Neither cover crops, nor tillage practices affected SOM contents at 0.20 m depth. An exception was observed on beans plots in which CT resulted on the lowest SOM content (8.5 dag kg-1) at 0-10 cm soil layer. Regarding green corn ears yield, CT adoption also resulted in lower weight (4.11 t ha-1) than those on NT (7.65 t ha-1), regardless of cover crop. On the other hand, the influence of cover crops on green corn yield relied upon tillage practices. Peanuts and sunn hemp performed best to improve corn yield in CT; peanuts and beans increased by 14 % the green corn ears yield in MT, while sunn hemp resulted in the highest total ear weight (9.42 t ha-1). Linear correlation of Pearson was significant for SOM and productivity green maize ears in minimum tillage beans (p <0.001; r = 0.996). After four years of absence or reduced soildisturbance, there was no increase in SOM levels. The plowing appears to be important for increasing the entry of C soil and chemical protection SOM of Argissols mainly in the surface layer of Coastal tablelands in brazilian northeast. Although the NT did not provide higher levels of SOM, the yield of green maize incommercial was significantly higher when adopting conservation systems.
O presente estudo teve como objetivo avaliar o efeito de diferentes sistemas de cultivo nos teores de matéria orgânica do solo (MOS) e na produtividade do milho verde (peso total das espigas) emArgissolo Vermelho-Amarelo (Ultissol) nos Tabuleiros costeiros da região nordeste do Brasil.. O experimento foi disposto em faixas experimentais com três repetições.Três práticas de cultivo [cultivo convencional (CC), cultivo mínimo (CM) e plantio direto (PD)] foram arranjadas em faixas (830 m²). Então, cada faixa foi dividida igualmente em doze unidades experimentais (60 m²), distante entre si a cada 1 x 10 m, onde quatro culturas antecessoras [guandu (Cajanus cajan (L.) Millsp.) crotalária (Crotalaria juncea), feijão (Phaseolus vulgaris) e amendoim (Arachis hypogeae)] foram semeadas previamente ao cultivo do milho. As culturas antecessoras e as práticas de cultivo não afetaram os teores de MOS da profundidade de 0.20 m. Uma exceção foi observada nas parcelas com feijão no qual o CC resultou no menor teor de MOS (8.5 dag kg-1) na camada 0-10 cm. Em relação a produtividade das espigas de milho verde, a adoção do CC também resultou em menor peso (4,11 t ha-1) que no PD (7,65 t ha-1), independente da cultura antecessora. Por outro lado, a influência da cultura de cobertura sob a produtividade do milho verde foi dependente da prática de cultivo. Amendoim e crotalária saíram-se melhor para aumentar a produtividade do milho no CC; amendoim e feijão aumentaram em 14 % a produtividade das espigas de milho verde no CM, enquanto crotalária resultou no mais alto peso total das espigas (9,42 t ha-1). A correlação linear de Pearson foi significativo para a MOS e produtividade de espigas de milho verde com crotalária sob o cultivo mínimo (p <0,001; r = 0,996). Após quatro anos da ausência ouredução do revolvimento do solo, não houve aumento nos níveis de MOS. A aração parece ser importante para aumentar a entrada de C no solo e a proteção química da MOS em Argissolos, principalmente na camada superficial. Embora o PD não tenha fornecido níveis mais elevados de MOS, o rendimento de espigas comerciais de milho verde foi significativamente maior ao se adotar sistemas conservacionistas.
Subject(s)
Crop Production , Zea mays , Organic MatterABSTRACT
Aims: As climate change related rainfall and temperature variability is being increasingly experienced in the SAT regions, we assessed climate change mitigation and adaptation potential of Conservation Agriculture (CA) by studying effects of minimum tillage (MT) and residue management practices on rain water use efficiency (RWUE), soil moisture, runoff, energy use and carbon dioxide emission in two maize-legume cropping systems. Study Design: The experiment was laid out in split-split plot design with four replications. Place and Duration of Study: The study was conducted at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) farm, Patancheru, Telangana, India during 2010-11 and 2011-12. Methodology: RWUE was calculated as maize equivalent yield divided by rainfall received during the crop season. Integrated digital runoff and soil loss monitoring unit (IDRSMU) was used to measure runoff. Soil moisture content was measured using the gravimetric method (0-30 cm depth) and neutron probe (60-90 cm depth). The soil organic carbon was analyzed following the Walkley-Black method [1]. The diesel consumption in MT and conventional tillage (CT) was estimated following Downs and Hansen (http://www.ext.colostate.edu/pubs) and emission of CO2 was estimated according to EPA, 2009 [2]. Results: Tillage and residue management practices did not show significant effect on RWUE except; CT having significantly higher RWUE over MT during 2011-12. Effect of cropping systems on RWUE was significant but variable during the two years of study. MT-RT (minimum tillageresidue retained) reduced total seasonal runoff by 28.62% and 80.22% compared to CT-RR (conventional tillage- residue removed) in 2010-11 and 2011-12, respectively. Similarly, MT-RT reduced rainwater loss and peak rate of runoff compared to CT-RR in both the years of study. During 2010, MT-RT had higher total soil moisture (v/v) in the 0-90 cm soil depth in sole as well as intercropped maize compared to CT-RR, however, during 2011 MT-RT had higher total soil moisture in sole maize only. As compared to CT, even though, MT improved SOC in 0-15 cm depth but lowered slightly in 15-30 cm depth. RT (residue retained) improved SOC in 0-15 and 15- 30 cm depths compared to residue removal (RR). MT-RT had higher or equal SOC in 0-15 and 15- 30 cm soil depths compared to CT-RR in both the maize-legume cropping systems. MT saved energy corresponding to 41.49 l of diesel per hectare annually compared to CT. Similarly, MT emitted 110.79 kg less CO2 annually on per hectare basis compared to CT due to reduced diesel use. Conclusion: CA, when adopted by following good agricultural practices and refined to suit the local conditions, could emerge as sustainable production system for climate change mitigation and adaptation of dryland cropping systems in semi-arid tropics of southern India.