Early planting and relay cropping: pathways to cope with heat and drought?

Maize (Zea mays) is an important food and cash crop of uplands in Southeast Asia, where it is often prone to drought and heat stress associated with climate change. This study aimed at assessing the effect of heat and drought on maize performance, testing coping strategies under such weather extremes, and understanding associated mechanisms. The experiment was carried out during 2018 in Thailand, using a split-plot design with three replications. Treatments were: July-planted maize sole cropping (control), July-planted maize-mungbean (Vigna radiata) relay cropping, and June-planted maize sole cropping. High temperatures and dry spells during July-August 2018 decreased maize growth strongest in the control and less so in maize relay cropping during generative growth stages, but not in June-planted maize sole cropping. Stress reduced maize nitrogen nutrition index by 40%. Relay-cropped maize had a significantly higher potential to keep stomata open (320 mmol m-2 s-1) than sole-cropped maize (100 mmol m-2 s-1). Δ13C of maize grains confirmed that June-planted maize (‑9.43‰) was less affected by dry spells and heat stress than July-planted sole cropped maize (‑10.23‰). Under relay cropping, the latter showed less water stress (δ13C: ‑10.12‰) compared to sole cropping and a higher soil water use. Maize was better able to cope with heat and drought stress when relayed-cropped, although less compared to early-planting of maize. Hence, the tested coping strategies are able to mitigate heat and drought effects on maize growth, while improving food security and crop diversification when relay-cropped with mungbeans

Agroforestry Interactions in Rainfed Agriculture: Can Hedgerow Intercropping Systems Sustain Crop Yield on an Ultisol in Lampung (Indonesia)?

The productivity of rainfed agriculture land developed on Ultisols is limited by physical and chemical constraints. These problems can be solved and consistently high yields obtained only by the development of comprehensive manage-ment systems. In the 1980s, hedgerow inter-cropping was promoted initially for improving soil fertility and sustainability of crop production on nutrient-depleted soils. However the previous enthusiasm for hedgerow intercropping is unsupported by scientific evidence and its labour demand too high. The question remains, is there a window of opportunity where the biophysical principle of hedgerow intercropping is sound? Research to compare the long-term performance of crops and trees in hedgerow intercropping and monocluture cropping is needed. This research has been conducted at long-term field experiment station at the BMSF-Project, Lampung, Indone-sia. The experiment site had non-nitrogen-fixing peltophorum (PP), nitrogen-fixing gliricidia (GG) and alternate peltophorum and gliricidia (PG) hedgerow intercropping and maize / groundnut monoculture (C) treatments. We concluded that the net interactions related to soil fertility and competition for growth resources in peltophroum were positive for crop yield in PP and PG but negative for GG. Even so, the PP and PG sys-tems resulted in similar yields as monocropping; however, hedgerow intercropping considerably improved soil fertility attributes

Effect of Toposequence Position on Soil Properties and Crop Yield of Paddy Rice in Northern Mountainous Region, Vietnam

Symposium Pape

Spatial differences in soil properties, crop yield and methane emission from paddy rice cascade, Northwest Vietnam

Session 2: Nitrogen, Green House Gasses and Agricultur

Assessing the effect of organic residue quality on active decomposing fungi in a tropical Vertisol using 15N-DNA stable isotope probing

15N-DNA stable isotope probing (15N-DNA-SIP) combined with 18S rRNA gene-based community analysis was used to identify active fungi involved in decomposition of 15N-labeled maize and soybean litter in a tropical Vertisol. Phylogenetic analysis of 15N-labeled DNA subjected to 18S rRNA gene-based community fingerprinting showed that organic residue quality promoted either slow (i.e. Penicillium sp., Aspergillus sp.) or fast growing (i.e. Fusarium sp., Mortierella sp.) fungal decomposers in soils treated with maize or soybean residues, respectively, whereas Chaetomium sp. were found as dominant decomposers in both residue treatments. Therefore, we have clear evidence that specific members of the fungal community used 15N derived from the two different organic resources for growth and stimulated early decomposition of maize or soybean decomposition. In conclusion, our study showed that 15N-DNA-SIP-based community analyses cannot only follow the flow of N from organic resources into bacteria, but also into the actively decomposing fungal communities of soils

Mineralización de nitrógeno en suelos de pasturas con Arachis pintoi

There is a lacking on information about the role of forage legumes to improve soil fertility on native pastures within tropical Mexico. Under this type of vegetation, continuous incorporation of residues from introduced forage legumes may contribute, from the N stored on its organic matter, to soil health restoring. Nitrogen soil mineralization using both anaerobic (ANA) and aerobic (AER) laboratory incubation methods was assessed in Ultisols soil samples at 0-5, 5-15 and 15-30 cm depths, from four tropical native pasture sites located at Veracruz, Mexico. Each pasture was associated to the introduced forage legume Arachis pintoi, with 3, 5, 8 and 11 yr after the forage legume was introduced. Also, pure stands of native pasture sites no mixed to A. pintoi were used as reference sites. In all cases mineralization rate decreased with the depth, AER method confirmed ANA results, since only 5 A. pintoi years old site yielded more mineralized N (207+-3.4 μ,,g N g-1 soil) than native pasture soils (166+-3.1 μ,,g N g-1 soil). Topsoil (0-5 cm) mineralized more N (104+-7.0 μ,,g N g-1) than 5-15 cm soil depth (70+-5.4 μ,,g N g-1). Although no significant positive effect of the legume on N mineralization with either method was observed, discussion is focused regarding to define if differences between types of pastures were due to low inherent soil N rather than changes in soil organic matter quality.Existe una falta de información acerca del papel de las leguminosas forrajeras para mejorar la fertilidad del suelo en pasturas nativas tropicales en México. En esta vegetación, la continua incorporación de residuos de leguminosas forrajeras introducidas al suelo puede contribuir, a partir del N contenido en su materia orgánica, a restaurar su fertilidad. Con el fin de determinar la mineralización de N proveniente de la leguminosa forrajera A. pintoi asociada a pasturas nativas, se usaron los métodos de incubación anaeróbica (ANA) y aeróbica (AER) en Ultisoles, a 0-5, 5-15 y 15-30 cm de profundidad, en cuatro sitios de pasturas nativas de Veracruz, México. Cada sitio tení­a 3, 5, 8 y 11 años asociado a Arachis pintoi. En todos los casos la tasa de mineralización decreció con la profundidad. AER confirmó los resultados de ANA, ya que sólo el sitio con 5 años asociado a A. pintoi mineralizó más N (207+-3.4 μ,,g N g-1 suelo) que los sitios no asociados (166+-3.1 μ,,g N g-1 suelo). Se mineralizó más N en los primeros 5 cm de suelo (104+-7.0 μ,,g N g-1) que a 5-15 cm de profundidad (70+-5.4 μ,,g N g-1). No se encontraron efectos significativos de la leguminosa sobre la mineralización de N con ninguno de los dos métodos, y se discute si las diferencias entre ambos tipos de pasturas se debieron a los bajos niveles de N inherentes a cada sitio, más que a cambios en la materia orgánica del suelo

Combined effects of drought and soil fertility on the synthesis of vitamins in green leafy vegetables

Green leafy vegetables, such as Vigna unguiculata, Brassica oleraceae, and Solanum scabrum, are important sources of vitamins A, B1, and C. Although vitamin deficiencies considerably affect human health, not much is known about the effects of changing soil and climate conditions on vegetable vitamin concentrations. The effects of high or low soil fertility and three drought intensities (75%, 50%, and 25% pot capacity) on three plant species were analysed (n = 48 pots) in a greenhouse trial. The fresh yield was reduced in all the vegetables as a result of lower soil fertility during a severe drought. The vitamin concentrations increased with increasing drought stress in some species. Regardless, the total vitamin yields showed a net decrease due to the significant biomass loss. Changes in vitamin concentrations as a result of a degrading environment and increasing climate change events are an important factor to be considered for food composition calculations and nutrient balances, particularly due to the consequences on human health, and should therefore be considered in agricultural trials

Total elemental composition of soils in Sub-Saharan Africa and relationship with soil forming factors

AbstractA thorough understanding of the variation in total soil element concentrations is important especially in the Sub-Saharan Africa (SSA) soil contexts for agricultural and environmental management at large scale. Fingerprinting of soil elemental composition may form a useful basis for evaluating soils in a way that relates to soil-forming factors and inherent soil functional properties. The objectives of this paper are to quantify the proportion of variability in total elemental composition by total X-ray fluorescence (TXRF) method of 1074 soil samples from the Africa Soil Information Service (AfSIS) Project baseline and to determine the relationships with soil forming factors. The samples were from 34 sentinel sites measuring 10×10km, randomized within major climate zones in SSA. Within each sentinel site there were sixteen spatially stratified 1km2 clusters, within which there were ten 100m2 plots. The within and between site patterns of variation in total element composition of 17 elements; Al, P, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Sr, Y, Ta, and Pb, were explored. Total element concentration values were within the range reported globally for soil Cr, Mn, Zn, Ni, V, Sr, and Y and higher than reported range for Al, Cu, Ta, Pb, and Ga. There were significant variations (P<0.05) in total element composition within and between the sites for all the elements analyzed with the greatest proportion of total variance and number of significant variance components occurring at the site (55–88%) followed by the cluster nested within site (10–40%) levels. The explorations of the relationships between element composition data and site factors using Random Forest regression demonstrated that soil-forming factors have important influence on total elemental composition in the soil. The fact that the soil-forming factors are related to the concentration of naturally occurring elements in the soil gives rise to the notion that they might be predicted from the soils' element composition. Results implied that >70% of variation in soil element composition patterns can be predicted using information in existing databases or readily observable features. Successful use of TXRF technique would open up possibilities for using total soil elemental composition fingerprints as a useful basis for characterizing soils in a way that relates to soil-forming factors and inherent soil functional properties