In the Vietnamese Mekong Delta, soil quality and crop yield are steadily declining under rice monocultures with three crops per year. The objective of this study was to evaluate the medium-term effects of rotating rice with upland crops and adding organic amendments on rice yield, and to relate this to soil quality. A field trial with split-plot design including two factors and three replicates was carried out from 2017 to 2020, over the course of nine consecutive cropping seasons. Crop rotations and organic amendments were applied as main-plot and subplot factors, respectively. The rotations were (1) rice–rice–rice (R–R–R), (2) soybean–rice–rice (So–R–R), and (3) sesame–rice–rice (Se–R–R), while organic amendment treatments included (i) no amendment (NO-AM), (ii) compost of rice straw and cow manure (RS+CM), and (iii) sugarcane compost (SGC); the composts were applied at a rate of 2.0 t ha⁻¹. The rotation cycle started with the so-called spring–summer (SS) season, followed by the summer–autumn (SA) season and ending with the winter–spring (WS) season. Rice yield significantly (p < 0.05) increased under organic amendments after nine growing seasons (2019–2020 WS), with an increment of 5.1% for RS+CM (7.07 ton/ha) and 6.1% for SGC (7.14 ton/ha). Contrary to our expectation, rotations with upland crops did not significantly increase rice yield. Rice yield significantly and positively correlated with an integrated soil quality index–SQI (r = 0.85) for the topsoil (0–15 cm), but not for the subsoil (15–30 cm). The increased availability of soil nutrients (Si and marginally also P) and improved soil physical properties probably induced by organic amendments, along with other soil properties under study, cumulatively attributed to enhanced rice yield. Repeated organic amendments thus becomes an effective management practice in improving soil quality under rice-based systems and could be applied to sustain rice yield in rice-producing regions with similar soil types and climatic conditions. Use of a SQI involving several soil quality indicators enables us to quantify the overall importance of soil fertility for rice yield versus other factors, and it provides an effective means of quantifying the integrated effect of improved management. Moreover, integrating a wide range of soil quality indicators in a SQI ensures its applicability across diverse settings, including different crop rotations and various soil types.

The study aimed to evaluate the soil environment characteristics of Vinh Long Province's perennial crop-growing area using cluster analysis (CA) and principal component analysis (PCA). Soil environmental quality data were collected in eight districts of Vinh Long province for 27 physical and...

The study assesses steel slag fertilizer's effect on rice yield on acid sulfate soil in Vinh Phuoc village, Tri Ton district, An Giang province. A field experiment with three treatments was established by the randomized block method with three replications. The fertilizer dose applied in individual treatments was: (1) 3 tons/ha lime, (2) 3 tons/ha steel slag fertilizer, and (3) 3 tons/ha compost in the experiment. The farmers' practice fertilizer rate of 131 kg N + 41 kg P2O5 + 108 kg K2O/ha was applied as the based treatment. Using steel slag fertilizer on acid sulfate soil at a dosage of 3 tons/ha in combination with inorganic fertilizers showed a tendency to improve soil chemical properties such as soil pH, ECe, soil organic carbon (SOM) content, CEC, total P, available P, and exchangeable cations (K, Na, Mg) content. The slag fertilizer affected the growth of rice plants, thereby helping to increase the yield and yield components of rice compared to other treatments. The steel slag fertilizer has improved soil properties and rice yield, which was statistically significantly different from other treatments. However, total nitrogen and calcium exchange content have not improved considerably. Therefore, applying inorganic fertilizers combined with steel slag fertilizer is an appropriate solution to enhance soil nutrients and increase rice yield.

Những tác động của các tiến trình tự nhiên và sử dụng đất làm thay đổi đặc tính đất. Nghiên cứu đánh giá sự thay đổi đơn vị bản đồ đất thông qua đặc tính và hình thái phẫu diện đất làm cơ sở cho sử dụng đất đai hiệu quả. Tổng hợp tư liệu, khảo sát đất theo tuyến với 20 điểm khoan sâu 2 m, 3 phẫu diện đất điển hình, 15 mẫu đất tầng mặt và 30 phiếu điều tra được thực hiện. Kết quả chỉnh lý bản đồ đất tỷ lệ 1/25.000 có 2 nhóm đất chính được xác lập gồm Gleysols (đất phù sa mới) và Plinthosols (đất phù sa cổ) với 5 đơn vị bản đồ đất. So với bản đồ đất 2016, đất phèn hoạt động nặng tăng 1,2%; đất phèn tiềm tàng nông thay đổi thành phèn tiềm tàng trung bình chiếm 97,6%. Phẫu diện đất được phân hóa mạnh có tầng phèn, tầng kết von và tầng chứa vật liệu sinh phèn. Tầng đất canh tác có nhiều chất hữu cơ chiếm gần 64%. Với sự thay đổi này thể hiện đất đai còn tiềm năng cho canh tác. Sử dụng đất và biện pháp quản lý phù hợp cần được nghiên cứu thực hiện để khai thác và sử dụng đất hiệu quả tại huyện Mộc Hóa, tỉnh Long An.

In the Vietnamese Mekong delta, soil quality and crop yield are steadily declining under rice monocultures with three crops per year. The objective of this study was to evaluate the medium-term effects of rotating rice with upland crops and adding organic amendments on rice yield and relate it to soil quality. A field trial with split-plot design including two factors and three replicates was carried out from 2017 to 2020, over the course of nine consecutive cropping seasons. Crop rotations and organic amendments were applied as main-plot and subplot factors, respectively. The rotations were: 1) rice–rice–rice (R–R–R), 2) soybean–rice–rice (So–R–R), and 3) sesame–rice–rice (Se–R–R), while organic amendment treatments included: i) no amendment (NO-AM); ii) compost of rice straw and cow manure (RS+CM), and iii) sugarcane compost (SGC); the composts were applied at a rate of 2.0 t ha-1. The rotation cycle started with the so-called spring–summer (SS), followed by summer–autumn (SA) and ended with the winter–spring (WS) season. Rice yield significantly (P < 0.05) increased by organic amendments after nine growing seasons (2019–2020 WS), with an increment of 5.1% for RS+CM (7.07 ton/ha) and 6.1% for SGC (7.14 ton/ha). Contrary to our expectation, rotations with upland crops did not significantly increase rice yield. Rice yield significantly and positively correlated with an integrated soil quality index SQI (r = 0.86) for the topsoil (0–15 cm), but not for the subsoil (15–30 cm). The increased availability of soil nutrients (Si and marginally also P) and improved soil physical properties probably induced by organic amendments, along with other soil properties under study, cumulatively attributed to enhanced rice yield. Use of a SQI involving several soil quality indicators enables to overall quantify the importance of soil fertility for rice yield versus other factors and it provides an effective means of quantifying the integrated effect of improved management. Moreover, integrating a wide range of soil quality indicators in a SQI ensures its applicability across diverse settings, including different crop rotations and various soil types.