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Spatial variability of hydro‐physical properties has long been observed, whereas temporal variation is much less documented and considered in studies and applications, particularly of paddy clay soils under different cropping systems. The objective of this study was therefore to assess the seasonal‐ and inter‐seasonal variation of selected hydro‐physical properties of a paddy clay soil under different rice‐based cropping systems with contrasting tillage. In a long‐term experiment, plots were arranged in a randomized complete block design with four treatments and four replications: (i) rice–rice–rice; (ii) rice–maize–rice; (iii) rice–mung bean–rice; and (iv) rice–mung bean–maize. Soil samples were collected at three depths (0–10, 10–20 and 20–30 cm) at three times during two cropping seasons, i.e., 15 days after soil preparation (DASP), 45 DASP and 90 DASP during the winter–spring and spring–summer seasons. Results show that temporal variability of soil bulk density, macro‐porosity (MacP) and matrix‐porosity within both seasons and between seasons was limited for cropping systems with upland crop rotations, whereas within season variation was significant for rice monoculture system. Observed variation in bulk density, matrix‐porosity and MacP was mainly associated with cropping system and soil depth. Field saturated hydraulic conductivity of topsoil showed great temporal variability, both seasonal and inter‐seasonal, in correspondence with MacP (r = 0·58). These results highlight the need of depth differentiated soil sampling and time consideration when evaluating management practices on soil physical properties and modeling the hydrological behavior of paddy soil. Copyright © 2017 John Wiley & Sons, Ltd.

The study aimed to assess the current agricultural production and to identify the criteria affecting the agricultural cultivation and overcome the limitations in agricultural production of Chau Thanh, A district of the Mekong Delta, Vietnam. The study collected primary from farmers using Participatory Rapid Appraisal tool, and discuss directly with experts and local agricultural managers. The results showed that economic development mainly based on agriculture (of which the paddy and fruit trees land were the most 13.577 ha (98,8%)). The five criteria were identified (techniques, physical, social, economic, and environment) and twenty-six sub-criteria, in which the production scale (0.084), infrastructure (0.071), total income (0.075) and profit (0.062) were the most important factors. The AHP analysis assisted in proposing several solutions such as infrastructure construction and non-structural solutions to cover the output of products to develop sustainable agricultural production. Therefore, the case study of Chau Thanh A district was used to support the development of agriculture production. Contribution/ OriginalityThis study identified the important factors affected agricultural production. Based on these factors, we propose and prioritize the suitable solutions and recommendations for policy-makers to develop sustainable agricultural production in the future effectively.

This study aimed to investigate effects of nitrogen (N) fertilizer rates and inoculation of rice seeds with N-fixing bacterium Gluconacetobacter diazotrophicus on the growth parameters and yield of OM5451 and OM6976 rice varieties in the Vietnamese Mekong Delta region. Nitrogen fertilizer rates of 50 kg N.ha-1 and 100 kg N.ha-1 were used, with latter reflecting farmer practice. Three rice seed inoculation methods were also employed: Seeds soaked in water for 24 hours and allowed to stand for 30 hours (control) (B0); Seeds soaked in water for 24 hours and inoculated with G. diazotrophicus for 30 hours (B1); Seeds soaked with G. diazotrophicus in water for 24 hours and allowed to stand for 30 hours. Applying 50 kg N.ha-1 without combining with NFB bacterium in this experiment generally resulted in less tillers, shorter plants, a lower SPAD index, and lower grain yield. Combining G. diazotrophicus bacterium with reduced N fertilizer of 50 kg N.ha-1 demonstrated rice growth and yield may be maintained in both varieties compared to 100 kg N.ha-1. These results providing a firm foundation for future research of adding NFB to paddy soils to decrease the N fertilizer requirement.

Background Cover crops and mulching can ameliorate soil porosity and nutrient availability, but their effects on the physical characteristics and nutrients in the raised bed soils are unclear. Methods The field experiment was conducted in a pomelo orchard from 2019 to 2021, with an area of 1,500 m2. The treatments included control (no cover crop), non-legume cover crop (Commelina communis L.), legume cover crop (Arachis pintoi Krabov & W.C. Gregory), and rice straw mulching (Oryza sativa L.). At the end of each year (2019, 2020, and 2021), soil samples were collected at four different layers (0–10, 10–20, 20–30, and 30–40 cm) in each treatment. Soil bulk density, soil porosity, and the concentration of nutrients in the soil were investigated. Results The results revealed that soil bulk density at two depths, 0–10 and 10–20 cm, was reduced by 0.07 and 0.08 g cm−3 by rice straw mulch and a leguminous cover crop, thus, increasing soil porosity by ~2.74% and ~3.01%, respectively. Soil nutrients (Ca, K, Fe, and Zn) at topsoil (0–10 cm) and subsoil (10–20 cm) layers were not significantly different in the first year, but those nutrients (Ca, K, Fe, and Zn) improved greatly in the second and third years. Conclusions Legume cover crops and straw mulch enhanced soil porosity and plant nutrient availability (Ca, K, Fe, and Zn). These conservation practices best benefit fruit orchards cultivated in the raised bed soils.

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In recent years, rice crop intensification, which has put a lot of pressure and led to a great change in soil resources and its distribution. In Haugiang province of Vietnam, under different land uses, the previous soil map (2008) has changed and out of date. The research aims to update the soil map of the province under different land uses. The collection of 175 soil profile description data, and 51 soil analysis profiles. Soil classification was followed WRB 2006. The results showed that two major soil groups were found, in which four diagnostic horizons (Mollic, Umbric, Plinthic, and Sulfuric); one diagnostic property (Gleyic); and one diagnostic material (Sulfidic) were identified, and 15 soil types were classified. The Gleysols soil group have 14 soil types (hamoGL, hamoGL(hu), monplGL), (moGL(ptip), moGL(ntip), moGL(dtip), (umGL(ptio), huGL(ptio), umpplGL(ntio), umGL(ntio), huGL(ntio), umGL(dtio), (mowsGL(ntip), umwsGL(ntio)) total area of 9,551.32 ha, accounting for 59.34%; while Anthrosols soil group have one soil type (RGah) area of 66,252.91 ha, accounting for 40.66%. Soil map of the province was updated according to WRB 2006, which pineapple, sugarcane crops have a high tolerance of acidity and fruit crops are mainly on Anthrosol soil group, where acid sulfate soils, low in soil pH and base saturation, are dominated. While rice cultivation is dominated on most of Gleysols soil groups, including alluvial and acid sulfate soils. The acid sulfate soils of the study area have low pH, high acidity, high Al content, and low base saturation, in which crops need high tolerance of low pH such as pineapple, sugarcane, fruit crops, but most of the crops should grow on a raised bed for easy to leach soil acidity and toxicity.

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