Organomineral fertilizer as an alternative for increasing potato yield and quality

ABSTRACT Organomineral fertilizer has great potential to replace synthetic fertilizers. The goal of this study was to determine an optimal substitution rate of organomineral fertilizer for mineral fertilizer to increase potato yield and quality. The experimental design was a randomized complete block with four replicates and six treatments, namely four substitution rates of organomineral fertilizer application (25, 50, 75, and 100% of mineral fertilizer demand), one rate of mineral fertilizer application (100% of mineral fertilizer demand), and the control (no fertilizer application). The organomineral application rates were tested as an alternative to substitute 25 to 100% of mineral fertilizer. The potato yield (total and in-class) and quality and plant and soil nutrient contents were monitored. The pH and total soluble solid contents had positive correlations with yield. Potatoes accumulated higher contents of K > N > P in the leaves, stems, and tubers. The organomineral fertilizer application rate of 3.7 t ha-1 (equivalent to 100% of mineral fertilizer demand) was the optimal rate to increase potato yield and quality. Organomineral fertilizer is a viable alternative to increase potato quality and yield and to increase plant and soil nutrient contents.

Effects of Soil and Foliar Applied Fertilizers on Growth, Yield and Sugar Quality of Two Sugarcane Cultivars under Rainfed Conditions

Background: In north-eastern Thailand, sugarcane is planted normally in late rainy season wherein the plants may experience drought stress during its early growth stage in dry season and waterlogging stress during late growth stage at peak of rainy season. Hence, the objective of the present study was to investigate the effects of soil application alone and soil combined with foliar application of nutrients on growth, yield and sugar quality of sugarcane grown under rainfed conditions. Methods: The field experiment was conducted during November 2016 to December 2017. A split-plot design with three replications was laid out. The two sugarcane cultivars (KK3, K93-219) were assigned as main plots. The fertilizer application methods were assigned as sub-plots that comprised of four treatments: (1) soil applied NPK, (2) soil NPK + foliar N and K applied at 90 days after planting (DAP), (3) soil NPK + foliar N and K applied at 210 DAP and (4) soil NPK + foliar N and K applied at 90 and 210 DAP. Result: The soil NPK + foliar N and K applied at 90 and 210 DAP improved yield components and cane yield. The cultivar K93-219 produced significantly higher cane yield than KK3. The fertilizer application methods and cultivars had no significant effect on sugar quality such as brix (%), purity (%), polarity (%), fiber (%) and commercial cane sugar (CCS-%).

Estimating Nutrient Uptake Requirements for Melon Based on the QUEFTS Model

Imbalanced and excessive fertilizer application has resulted in low yields and reduced nutrient use efficiency for melon production in China. Estimating nutrient requirements is crucial for effectively developing site-specific fertilizer recommendations for increasing yield and profit while reducing negative environmental impacts. Relationships between the yield and nutrient uptake requirements of above-ground dry matter were assessed using 1127 on-farm observations (2000–2020) from melon production regions of China. The quantitative evaluation of fertility of tropical soils (QUEFTS) model was used to estimate nutrient requirements. It predicted a linear increase in yield at balanced nutrient uptake levels until the yield reached approximately 60–80% of the potential yield. In order to produce 1000 kg of fruit, 2.9, 0.4 and 3.2 kg/ha of N, P and K (7.2:1.0:7.8), respectively, were required for above-ground parts, while the corresponding nutrient internal efficiencies were 345.3, 2612.6 and 310.0 kg per kg N, P and K, respectively, whereas 1.4, 0.2 and 1.9 kg of N, P and K were required to replace nutrients removed after harvest. The corresponding fruit absorption rates were 47.0%, 59.5% and 58.2%, respectively. Field validation experiments confirmed the consistency between observed and simulated uptake rates, indicating that this model could estimate nutrient requirements. These findings will help develop fertilizer recommendations for improving melon yield and nutrient use efficiency.

Early Effects of Fertilizer and Herbicide Reduction on Root-Associated Biota in Oil Palm Plantations

To secure high yield, tropical oil palm plantations are fertilized, and understory vegetation is controlled by chemical clearing with herbicides. These treatments cause a drastic turnover of soil microbes and cause loss of beneficial mycorrhizal fungi. Here, we tested if reduced fertilization and weeding instead of conventional treatments restored beneficial ecological groups associated with roots. We conducted our study one year after the start of the reduced management in large-scale oil palm plantations. We hypothesized that reduced fertilizer application and weeding result in shifts of the root-associated species composition because changes in the management regimes affect belowground biomass and nutrients in soil and roots. Alternatively, we hypothesized that the legacy of massive soil fertilization and herbicide application preclude compositional shifts of root-associated biota within short time periods. We did not find any significant treatment effects on root nutrient contents, root biomass, and nutrients in soil. At the level of species (based on operational taxonomic units obtained by Illumina sequencing) or phyla, no significant effects of reduced management were observed. However, distinct functional groups showed early responses to the treatments: nematodes decreased in response to weeding; yeasts and ectomycorrhizal-multitrophic fungi increased under fertilizer treatments; arbuscular mycorrhizal fungi increased under fertilizer reduction. Since the responsive ecological groups were represented by low sequence abundances, their responses were masked by very high sequence abundances of saprotrophic and pathotrophic fungi. Thus, the composition of the whole root-associated community was unaffected by reduced management. In conclusion, our results show that changes in management regimes start to re-wire critical constituents of soil–plant food webs.

Effect of P fertilizer and precipitation on wheat under permanent beds in the absence of N fertilizer application

Environmental conditions contribute to a large percentage of wheat yield variability. This phenomenon is particularly true in rainfed environments and non-responsive soils to N. However, the effect of P application on wheat is unknown in the absence of N fertilizer application. This study was conducted from 2012 to 2019 in permanent beds established in 2005. Treatments were arranged in a split-plot design and consisted of superimposing three P treatments (foliar, banded and broadcast application) plus a check (0P) within each one of four preceding N treatments (applied from 2005 to 2009). Foliar P generally showed a greater response than granular P treatments even though the soil tests high P (>30 mg/kg). Precipitation estimated for two different growth intervals explained through regression procedures the Years' effect. Seasonal precipitation (224–407 mm) explained variation of relative yield, N harvest index (NHI) and P agronomic efficiency (AE). Reproductive stage precipitation (48–210 mm) explained soil N supply. In dry years, foliar P application improved predicted relative yield 14% and AE 155 kg grain/kg P compared to granular P treatments. Similarly, soil N supply increased 15 kg/ha in dry moisture conditions during the reproductive stage. The NHI consistently improved over the crop seasons. This improvement was relatively larger for 0 kg N/ha. On average, NHI increased from about 0.57 to 0.72%. Normalized difference vegetation index (NDVI) readings at the booting growth stage were negatively associated with NHI. Foliar P in this non-responsive soil to N showed the potential to replace granular P sources. However, the omission of granular P needs to be further studied to estimate the long-term effect on the soil P test.