The objective of this study was to determine the effect of bio-NPK-TE fertilizer on rice growth and grain yield by reducing fertilizer application. The experiment was carried out in 2 consecutive crops, from Winter-Spring 2018-2019 to Summer-Autumn 2019 season on alluvial soil. The main was arranged format in randomized completely block design-RCBD) with nine treatments: (T1) fertilized 100%NPK (80N-60P2O5-50K2O kg/ha-recommendation of Cuu Long rice research institute - CLRRI), (T2) fertilized 100%NPK (80N-13P2O5-13K2O kg/ha-as the untreated control), (T3) fertilized of bioligical NPK-TE 30-5-5 (80N-13P2O5-13K2O kg/ha), (T4) 80%NPK of T1, (T5) 80%NPK of T2, (T6) 80%NPK of T3, (T7) 60%NPK of T1, (T8) 60%NPK of T2 and (T9) 60%NPK of T3. The results showed that reducing 40% of the fertilizer (NPK-TE bio) could maintain rice height and the number of tillers compared with the recommendation. Besides, applying NPK-TE bio-fertilizer could also maintain the yield components and grain yield in the condition of fertilizing by 20-40% lower than the recommendation.

The aim of this research was to study the effect of humate-coated urea fertilizer combined with probiotics NPISi on the growth and yield of rice in Chau Thanh A district, Hau Giang province. This study contributed to reduce in amounts of inorganic fertilizer and rice seeds used. On - farm trials arranged in accordance with a Randomized Complete Block Design (RCBD) were conducted with 3 replications of 1000 sq m per rep. in the fields of the local farmers. Two treatments were used in which the farmers' practice is as control treatment (127N - 89P2O5 - 23K2O kg.ha-1, thick seeding 200 kg.ha-1), and the other treatment is a modern practice with fertilizer formula of 50N - 30P2O5 - 30K2O kg.ha-1 (1/2 recommended doses of NPK), using humate coated urea, combining probiotics. The results showed that the use of humate coated urea combined with probiotics NPISi helped reduce 60% N, 66% of P205 and 35% of the sowing seeds and no significant differences of rice yield between farmers’ practice and new practice  (5.30 tons.ha-1 in experimental field and 5.44 tons.ha-1 in farmers’ field). The results also indicated that the experimental field has a higher total profit than the farmers' field. Besides, the content of soil nutrients and density of total soil microorganisms (fungi, bacteria and actinomycetes) in the experimental field was higher and statistically difference from the farmers' field.

There is a finite limit of arable land so that global food security depends on a focused effort to improve soil fertility and increase productivity of food crops and fertilizer plays a significant role. Therefore, the fertilizer industry has been developing fertilizer products to meet the range of site- and crop-specific conditions, enhancing nutrient management and minimize environmental impact. Four types of these fertilizers consist of: (1) Fertilizers supplemented with secondary nutrients (S, Ca, Mg) and micronutrients (e.g. Zn, B); (2) Stabilized, slow- and controlled release fertilizers; (3) Fertilizer products contains biostimulants; and (4) Soluble/liquid fertilizers (fertigation, foliar sprays). Along with that trends, Petroleum Vietnam Ca Mau Fertilizer Company successfully developed new bio-mineral fertilizer lines which increasing the nutrient use efficiency, crop development and yield, the such as N.Humate TE 35.7 (35% N; 7% Humic acid (C); 1000 ppm Zn; B 400 ppm), N.Humate TE 28.5 (28% N; 5% Humic acid (C); 1000 ppm Zn; B 400 ppm), Bio-Nitrogen TE (32% N; 5% Fulvic acid (C); 1.000 ppm Zn; B 400 ppm), NPK Biological TE 30-5-5 (30% N; 5% P2O5; 5% K2O; 2% HA; 2% FA; 200 ppm Zn; 100 ppm B).

The objectives of this study was to assess the efficacy of biological nitrogen fertilizer on growth and grain yield of rice cultivated in alluvial soil and potential acid sulfate soil in the Mekong Delta area. The field experiment was conducted in Summer-Autumn 2018 for alluvial soil with river sediment deposition and Summer-Autumn 2019 for potential acid sulfate soil. These experiments were laid out in split-plot design with three replicates. The sub-plots included two kinds of N fertilizer: (i) urea-Ca Mau nitrogen fertilizer, and (ii) Innovative biological nitrogen fertilizer and the main plots included three different application doses: 60% (48 kgN/ha), 80% (64 kg N/ha), and 100% (80 kgN/ha). The results showed that the height of rice plant, tillers, SPAD index, and rice yield of treatments with application doses of 60-80% N from innovative biological nitrogen fertilizer were not significantly different from the positive control treatment applying 100%N from Ca Mau nitrogen fertilizer. Thus, results of this study recommended to apply this innovative nitrogen fertilizer for paddy rice when cultivated in alluvial soil and potential acid sulfate soil in the Mekong Delta area.

The objectives of this study were to calibrate and validate the CERES-Maize model and simulate the response of maize growth and yield to different doses of nitrogen and organic fertilizers in alluvial soil. Field experiments were carried out from August 2015 to April 2016 at the Soil Science Department, Can Tho University to collect data for model calibration and validation. The calibrated and validated results showed that there were good agreements between simulated and observed data, indicating through the statistical parameters, i.e. yield (EF:0.85 – 0.99; RMSE:181.49 – 669.71 kg/ha; nRMSE: 3.87 – 12.13 %); above-ground biomass (EF:0.97 – 0.98; RMSE:672.91 – 942.80 kg/ha;, nRMSE: 8.01 – 10.39 %); leaf number (EF: 0.90 – 0.95; nRMSE: 7.81 – 12.04 %. Meanwhile, the simulated leaf area index was rather good agreement to the observed data, i.e. EF:0.69 – 0.82 và nRMSE: 15.65 – 20.47%. Maximum temperature and rainfall were the parameters having the highest sensitivity among the others.

The objective of this study was to evaluate the potential of rice farming models in Vi Thanh city, Hau Giang province. The quantitative approach was applied by FAO (1976) to assess the natural suitability and suitable land classification for land use types (S1, S2, S3 and N). The results showed that Vi Thanh city including seven soil groups: Anthropic-Regosols was about 5,371.42 ha (45.19%), Mollic-Gleysols was 2,630 ha (22.13%), Eutric-Gleysols was 1,814 ha (15.26%), Epi-ProtoThionic-Gleysols was 1,458 ha (12.27%), Epi-OrthiThionic-Gleysols was 238 ha (2.00%), Endo-OrthiThionic-Gleysols was 203 ha (1.71%) and Endo-ProtoThionic-Gleysols was 172 ha (1.44%). This study area had 11 soil units and 5 land suitability zones (I, II, III, IV and V). There were 4 land use types: double rice, triple rice, rice-upland crops and rice-fish. In general, all land suitability zones I, II, III, IV and V were adaptive capacity from high to the highest in all land use types in this site.

The research was to evaluate the presence of sulfuric horizon, sulfidic materials (SM) and soil fertility to plan the proper fertilizer application. Soil morphological characteristics were directly described in the field, and soil samples from original horizons were collected to analyze the physicochemical parameters. The results showed that soil profiles from Tan Tien site were classified as active acid sulfate soil (ASS) with shallow presence of SM at 35-70 cm, and potential ASS with shallow presence of SM at deeper 30-75 cm while profiles from Hoa Tien location were categorized as potential ASS with deep presence of SM. For parameters of soil chemistry, surface soil pHKCl was lower than 4.0. Concentration of Al3+ and Fe2+ toxicity was lower than 5.0 meq Al3+ 100 g-1 and 10 mg kg-1, respectively. Besides, total nitrogen was evaluated at medium level, and total phosphorus at low threshold, with 0.41 – 0.55% and 0.008 – 0.058%, respectively. Concentration of available ammonium and soluble phosphorus in top soil layer was 75.5 – 186.7 mg NH4+ kg-1 and 38.0 – 45.6 mg P kg-1. However, soil phosphorus fractions of aluminum and ferrous phosphorus possess high concentration (76.0 – 188.6 and 18.5 – 42.1 mg P kg-1) on top soil surface. For soil physical characteristic as soil texture was determined as clay and silty clay. In general, fertility of ASS cultivated pineapple is low based on morphological and physicochemical properties.

The research was aimed at describing soil profiles morphology and surveying soil physical and chemical characteristics in relation to cropping patterns in some types of raised bed soils in Chau Thanh district, Ben Tre province (CTBT). Samples taken by soil horizons were used to determine physical and chemical properties. Crop intercorp - raised beds soils of cocoa intercropped coconut (CTBT01) and cocoa (CTBT02). The soils are classified as Gleyic ANTHROSOLS (according to WRB classification), with loamy clay soil, 2 soil profiles, were observed depth> 60 cm at CTBT02 point (pyrite is color 2.5YR2 /1) and they were observed depth >75 cm at CTBT01 point (pyrite is Gley1 4 /10Y) away from top soil.  Two soil profiles have average surface pH value (4.91-5.88), low organic matter (2.36 to 2.76% C), low N-total (0.168-0.189% N), P-total at the rich and average point, respectively at CTBT01 and CTBT02 (0.253 and 0.091% P2O5), average K-exchange (1.26-1.53% K2O). P-exchange, Mg-exchange and CEC on cocoa intercropped coconut soils with higher value than specialized cocoa soils.

The study was conducted to evaluate the effects of using salt-tolerant crops (Sesbania rostrata L.) on reclaiming salt-affected rice soil and improving the rice yield. The research was carried out in clay pots (containing 10 kg dry soil) which were arranged in a completely randomized design (CRD) with 3 treatments including 3 levels of dilute sea water amendment (0‰, 3‰, 6‰) and 4 replicates for each treatment. OM7347 rice cultivar was grown soon after harvesting of S. rostrata. The results indicated that S. rostrata showed the great ability to reduce soil ECe (decreased 12,2%-17,7%); lowering soil exchangeable Na+ (decreased 11,4%-19,5%) and hence for decreasing soil SAR and ESP. By contrast, exchangeable Ca2+ was increased in soil at harvest in comparison of that before planting. There was a less impact of salinity stress on growth, biomass and nutrients uptake (Mg2+, N, P2O5, K2O) in S. rostrata. However, proline accumulation and the uptake of Na+, Ca2+ by S. rostrata were increased following salt amendment.  Planting S. rostrata in salt-affected soil (0‰, 3‰ treatment) helped to increase significantly rice yield and hence they were likely to improve rice yield cultivated afterward better.

CH4 and N2O emissions from paddy soil plays an important role in reducing greenhouse gas emissions. This study was conducted to evaluate and compare CH4 and N2O emissions from a paddy soil supplemented by 2 types of biochar. The study was set up with 7 treatments including 2 types of rice husk biochar (i) produced by the slow pyrolysis in a laboratory (RB-lab) and (ii) a commercial rice husk biochar (RB) at 0.2, 0.5 and 1% and the control (without biochar). The CH4 emission of all treatments supplemented with either RB-lab or RB was significantly reduced with that of the control (p

The aim of the study was to evaluate the efficacy of five silicate solubilizing bacteria on growth and productivity of Mot Bui Do rice cultivar on saline soil in rice-shrimp farming system in Phuoc Long district, Bac Lieu province. The randomized complete block design field experiment was conducted with 4 replicates and 15 treatments. The results showed that treatments inoculated with bacteria had significantly higher levels of soluble silicate concentration in soil and silicate concentration in dry biomass, chlorophyll content in rice leaf, strength of internode 1, 2, and 3, and rice yield as compared to treatments without bacterial inoculation. Moreover, treatments inoculated with either a mixture containing five bacteria or RTTV_12 strain in a combination with 100%NPK and 100 kg CaSiO3.ha-1 had the highest rice yield of 5.66 and 5.35 ton.ha-1, respectively while rice yield of the positive control treatment (recommended 100%NPK) and recommended 75% or 100%NPK added 100 kg CaSiO3.ha-1 treatment were 4.79, 4.82 and 5.04 ton.ha-1, respectively. Therefore, these five silicate solubilizing bacteria are considered to have a potential in producing bio-fertilizer to enhance the growth and productivity of rice when grown on salt affected soil.

Nitrogen fertilizers containing urease nBTPT enzyme inhibitors and DCD nitrification inhibitors were investigated on saline rice soil in Tran De, Soc Trang in WS2018 and DS2018-2019. The objectives of the project is to evaluate the effectiveness of fertilizer blends of nBTPT and DCD on rice yield, economic efficiency and greenhouse gas emissions. The results showed that the combination of active ingredients nBTPT and DCD + nBTPT with urea increased the yield of rice from 0.55 to 0.74 tons/ ha compared to un-mixed urea. The combination of active ingredients helps to increase profits, increase agronomic efficiency and reduce N2O emissions compared to un-mixed urea in both crops.

This study is aimed to survey the soil morphological and physico-chemical characteristics of the raised-bed soil profiles under the cultivation of Nam Roi pomelo trees in Chau Thanh district, Hau Giang province. The study was carried out from March to August, 2019. The results showed that the soils under study were classified as Gleyic Anthrosols, characterized by a silty clay texture, including four main distinguished horizons (A, Ap, Bg1 and Cr) without sulfuric horizons. The chemical properties of the soils were characterized by the low to rather low pH values (4.0 – 6.0) of the top soil and tended to decrease gradually with depths. Whereas, the available P content of the top soils ranged from moderate to high and tended to decline gradually with depths. The organic matter contents of the top soils were low for the three profiles, whilst the CEC values were estimated to be moderate. The exchangeable cation contents of Na+ and K+ varied from low to moderate, meanwhile the Ca2+ and Mg2+ values fluctuated remarkably over the genesis horizons.

The objective of this study was to evaluate the effects of biological NPK-TE fertilizer on the yield and quality of “xuong com vang” longan fruit in the alluvial soil in Tien Giang province. The experiment five treatments included: (T1) fertilizer does 1.265N-715P2O5-1.265K2O (g/tree/year) as the control in which the urea fertilizer, (T2) 100%N of biological NPK-TE 25-10-5, (T3) 100%N of bioligical NPK-TE fertilizer 30-5-5, (T4) 80%N of biological NPK-TE 25-10-5, (T5) 80%N of biological NPK-TE 30-5-5 and there were three replicates for each treatment. The surveyed parameters included yield components, yield and fruit quality. The results showed that the reduction of 20%N as bioligical NPK-TE fertilizer did not significantly affect on the fruit quality and yield as compared to the control treatment.

Soil degradation is of great concern in the world due to its adverse impact on food security. In the Mekong Delta (MD), degraded agricultural soils were evaluated through soil quality indicators related to physical chemical and biological soil properties. Degraded soils have been clearly exposed in the triple-rice cropping system, top soil lost of rice fields, old constructed raised beds of fruit orchards. One of the effect factors can be due to farmers' inappropriate farming technique and nutrient management such as high dose of inorganic N, P fertilization, unbalanced nutrients, little or no use of organic fertilizers resulted in a reduction of soil supplying nutrient capacity, increasing soil-borne diseases, reducing crop yields. Our studies in MD indicated that using compost, bio-organic fertilizers which were composted in the right way, combining balanced inorganic fertilizers, were very effective ways to improve and to prevent soil degradation. This way of management needs to be recommended and developed. It’s very important and needs the involvement and action of soil scientists, fertilizer producers, agricultural managers and farmers for the successful of sustainable agricultural development and friendly environment in MD.

To evaluate N, P, and K internal nutrient efficiencies of maize, on-farm experiments have been conducted alluvials soil An Phu – An Giang following the QUEFTS model. The QUEFTS model was used to estimate the nutrition at different yield potential. The database used included 560 measurements of maize yield, total dry matter and nutrient uptake. Results showed that the grain yield of maize (15,5%) on the alluvial soil of An Phu - An Giang in Winter-Spring crop ranged from 4,210 to 13,826 kg/ha compared to an average of 9,850 kg/ha. Simulating soil data of An Phu - An Giang according to QUEFTS model with linearly increased grain yield when NPK nutrient uptake is respectively 23.6 kg N, 3.73 kg P and 14.5 kg K above 1 ton of grain, when the grain yield reaches about 60-70% of the yield potential. The final yield estimated as the average yield calculated for nutrient pairs from the parabola curve equation was 7,657 kg/ha. Optimal nutrient internal efficiency (IE) (42.4 kg/kg N, 268 kg/kg P and 69.0 kg/kg K) when the yield reaches 7 tons/ha.

This study is aimed to evaluate the effect of organic fertilizer combined with chemical fertilizer, especially nitrogen fertilizer. Nitrogen fertilizer was reduced from 20%-100% replaced by organic fertilizer. The studies have been recorded on the productivity and quality of rice, as well as comparing the effectiveness of the cultivation model as compared with applying completely chemical fertilization (100% NPK) as recommended or farm which was cultivated by farmers. The results showed that in substitution of chemical fertilizer (Nitrogen) from 30-60% through organic fertilizer had given rice yield and economic efficiency to increase higher when applied chemical chemistry (100% NPK) as recommended and cultivation of farmers. In addition, the results were also recorded when applying organic fertilizer that reduces residue of pesticide in rice grains at harvested time.

This research has been conducted on Nam Roi grown in raised bed at Chau Thanh-Hau Giang. This study is aimed to: investigate effect of organic fertilizer application on improving soil chemistry characteristics and fruit yield of Nam Roi pomelo. Two different models were chosen including applied and without applying organic fertilizer, which were similar in cultural practice and plant age (3-5 years old). The results showed that, soils of the two models were not significantly different in soil texture, pH, EC and exchangeable Na. However, the model of applied organic fertilizer showed higher soil CEC, organic matter content, available phosphorus (Bray-2) and exchangeable cation (K, Ca and Mg). Applying organic fertilizer gave higher fruit yield (10.7 tons/ha) than that of without applying organic fertilizer (7.24 tons/ha).

The aims of this study were to investigate the presence and the root colonization of arbuscular mycorrhiza (AM) fungi and to evaluate effects of some soil chemical parameters on the presence and the root infection of AM fungi in rhizosphere and rice roots in paddy soils at Hau Giang province. Thirty samples of rhizosphere soil and 30 samples of rice root were collected when rice plant were 50-60 days old for analyzing. The results showed that all root samples had the infection of AM fungi (7- 68%) and presence of AM spores in soil samples. Genera of Glomus and Acaulospora were dominant in those rhizopheral samples. In addition, the percentage of rice root colonization of AM fungi was positively correlated with soil pH (r = 0,85*), negatively correlated with soil EC (r = -0,72*), soil organic matter (r= -0,83*) and total nitrogen (r = -0,67*) in soils. There was no correlation between the number of AM spores with the soil chemical parameters.  These study results showed that the percentage of rice root colonization was affected by some soil chemical parameters but not for the AM spores in the paddy soils at Hau Giang province.

Agricultural production and food production of the Mekong Delta have been forecasted to be greatly affected in the future due to climate change and impacts of saline intrusion. Practical strategies are needed in integrated management of land and crops to ensure food security. Field experiments in this study were conducted on triple rice cultivation farms in U Minh Thuong district, Kien Giang province and Thanh Phu district, Ben Tre province. These areas are at risk of water shortage and saline intrusion in the annual dry season. The experiments were conducted in a randomized complete block design of 4 treatments and 4 replicates. These treatments used soil improvement products including organic fertilizer, biochar and silica with the aim of maintaining soil quality and crop productivity in production compared to a control treatment. Results of field experiments showed that biochar application (10 tons/ha/crop) resulted in improvement of organic and available nitrogen content (18.7 mg N/kg) while application of sugarcane filter cake compost (5 tons/ha/crop) was only recorded its effect on the growth of rice compared to the control and silicon fertilizer treatments. Rice yields of experimental treatments were not significantly different after one studied cropping season. Further studies are needed to evaluate residual effects of these products on increasing the crop yield in cultivated areas predicted likely to be affected by drought and salinity in the future.

The study is aimed to change traditional practices of rice cultivation (using conventional, unbalanced fertilizers and too many seeds) of farmers in acid sulfate soils with 2 rice crops/year in Hoa An commune, Phung Hiệp district, Hậu Giang province. Cultivation model under the improved farming method (improved model) using NPK slowly released fertilizer, urea humate, potassium humate and reduced seeding amount were conducted through two rice crops (Winter-Spring 2018 - 2019 and Summer-Autumn 2019) with an area of ​​3000 m2 / model. The results showed that the improved model had a higher pHH2O, the amount of available phosphorus in the soil increased, the Al3+ and H+ content decreased, significantly different from the control model. The productivity of the improved model rice was (6.19 tons/ha) significantly higher than that of  the control model (5.67 tons/ha) in the Winter-Spring crop. In the following crop (Summer-Autumn crop) there was no statistically significant difference in rice yield between the improved model (5.57 tons/ha) and the control model (5.05 tons/ha). The improved model helped farmers save 30% of the seed sowing seed, 50% of the amount of N and P fertilizers,  and gain higher profits (by 5.4 and 3.5 million VND/ha, respectively for Winter-Spring and Summer-Autumn crops).

The study was aimed to investigate the seed germination and growth promoting capacity of eight bacterial strains capable in both nitrogen-fixation and IAA synthesis for water spinach under the laboratory and pot condition. The seed germination promotion test was carried out by soaking water spinach seeds in a bacterial suspension (~106 cfu/mL) for 4 hours, then inoculated seeds were placed on petri dish and glass tube containing 1% agar medium. The pot experiments were conducted with five selected bacterial strains introduced into the soil with two levels of the chemical nitrogen fertilizer dose application (75% and 50% of recommended chemical N fertilizer fomular). Results showed that five out of eight tested bacterial strains showed their significantly higher capacity in seed germination rate of water spinach (varied from 82.3% to 85.5%) compared to other bacterial strains and the control treatment without bacterial inoculation. In addition, height, root length and fresh biomass of the seedling of the treatments inoculated with these five bacteria were also significantly higher than other remaining treatments. Among them, Paenibacillus cineris TP-1.4 was the best strain in stimulating the growth of water spinach and especially in reducing up to 25% of recommended chemical nitrogen fertilizer formula in two consecutive crops under the pot condition. The plant height, diameter, content of chlorophyll, fresh and fry biomass of water spinach in the treatment with TP-1.4 strain and together with 25%N reduced were not ignificantly different from those in the recommended chemical nitrogen fertilizer fomula treatment.

Site Specific Nutrient Management (SSNM) is an approach to feeding rice with nutrients as and when needed. The research has been conducted in eight locations, three rice crops from 2016-2018. Objective of the research was to evaluate the response of rice yield to NPK and establish the fertilizer formular for rice grown in major soil groups in MD. Results showed that the N recommended rate for rice in alluvial soils was 85-95 kg ha-1, on the other hand, acid sulfate soils and saline affected soils was 70-80 kg ha-1. In case of returning rice straw to the soil, the recommendation rate of P and K were 30-45kg P2O5 ha-1 and 25-35kg K2O ha-1, respectively.

This study was examined the effect of fresh spent coffee ground (FSCG) on growth and yield of rice, soil chemical and biological properties under the nethouse conditions. Rice was continuously cultivated in acid sulfate soil taken from Phung Hiep, Hau Giang. Eight different treatments including the control (no added fertilizer), 0.5%, 1%, 2%, 3%, 4% and 5% of FSCG applied (w/w, based on the dry soil mass) with 50% recommended inorganic fertilizer fomula and the treatment with recommended inorganic fertilizer (100N-60P2O5-30K2O) were conducted with four replicates for each treatment. The FSCG was applied into soil only in the first crop with five application period. Parameters of growth, yield of rice, pH, EC and microbial numbers in soil were sampled. The results showed that treatments of 1%, 4% and 5% of FSCG with 50% recommended inorganic fertilizer fomula had the growth and yield of rice lower than those of the recommended inorganic fertilizer treatment. However, in these treatments, the numbers of soil bacteria, fungi, nitrogen fixing bacterial and phosphate solubilizing bacterial increased significantly compared to those in other treatments. Thus, as a prospect of soil amendment in sustainable agricultural development, FSCG can be applied with an application dose of 1% into acid sulfate soil for rice growth and yield.