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What was the primary benefit of using controlled release fertilizers (CRF) over conventional urea?

  • CRF applications lead to faster nitrogen leaching.
  • CRF maintains a controlled nitrogen release that matches crop requirements. (correct)
  • CRF applications require more frequent applications.
  • CRF is less effective in enhancing crop yields.

What factor contributed to the increased nitrogen efficiency in rice crops with CRF application?

  • Increased watering frequency.
  • Higher urea concentration in soil.
  • Decreased root growth.
  • Enhanced nitrogen assimilatory activity. (correct)

What was a potential reason for the lower yields observed in treatments T2H and T3H despite utilizing CRF?

  • The nitrogen application rate was insufficient for optimal crop requirements. (correct)
  • Higher nitrogen application rates were used.
  • They used non-hydrogel based nitrogen sources.
  • They were applied too late in the cultivation period.

What percentage of nitrogen was released in the soil before rice cultivation according to the study?

<p>75% (D)</p> Signup and view all the answers

Which of the following statements is true about CRF's performance in soil?

<p>CRF degrades over time while maintaining available nitrogen content. (B)</p> Signup and view all the answers

What was the nitrogen utilization correlation mentioned in relation to rice crops?

<p>Glutamine synthetase activity is positively correlated with nitrogen utilization. (C)</p> Signup and view all the answers

Which statement best describes the impact of CRF on grain yield?

<p>CRF treatments can improve yield, but results may vary with application rates. (D)</p> Signup and view all the answers

During which phase of rice cultivation did the nitrogen release rate increase to 87%?

<p>After rice cultivation. (D)</p> Signup and view all the answers

What was the optimum nitrogen rate applied that resulted in maximum grain yield for upland rice?

<p>90 kg N ha−1 (A)</p> Signup and view all the answers

Which of the following best describes the nitrogen use efficiency (NUE) observed in T4H CRF?

<p>52.6% (B)</p> Signup and view all the answers

How did the application of CRF with 75% of the recommended N (T4H) compare to conventional methods?

<p>It improved grain yield compared to 100% N application. (C)</p> Signup and view all the answers

What was the highest observed harvest index (HI) for T4H CRF?

<p>45.5% (A)</p> Signup and view all the answers

What was associated with the higher grain yield observed in T4H CRF?

<p>Increased panicle number. (A)</p> Signup and view all the answers

Which nitrogen rate was not among the treatments tested in the study?

<p>150 kg N ha−1 (C)</p> Signup and view all the answers

What effect did the urea-loaded cellulose hydrogel have on N agronomic efficiency (NAE) in T4H CRF?

<p>It reached 12.8 kg kg−1. (D)</p> Signup and view all the answers

What is a key benefit of using controlled-release fertilizers (CRF) in the study?

<p>They improve nitrogen application efficiencies. (C)</p> Signup and view all the answers

What is the main advantage of using CRF hydrogels in rice cultivation?

<p>They degrade almost completely after 135 days. (D)</p> Signup and view all the answers

Which nitrogen application method resulted in higher rice yields and N efficiencies?

<p>Single basal application of CRF with 75% N. (B)</p> Signup and view all the answers

What was the percentage increase in rice yield when using CRF hydrogels compared to the control?

<p>71% (B)</p> Signup and view all the answers

What does NUE stand for in the context of nitrogen usage in rice production?

<p>Nitrogen Use Efficiency (B)</p> Signup and view all the answers

How did CRF hydrogels affect N uptake in rice cultivation?

<p>Increased N uptake with higher panicle number. (B)</p> Signup and view all the answers

What was observed regarding CRF weight loss during the study?

<p>Weight loss reached up to 97%. (A)</p> Signup and view all the answers

Which of the following was not a reported benefit of using CRF in rice cultivation?

<p>Higher nitrogen losses compared to traditional methods. (D)</p> Signup and view all the answers

What is the NAE measure referred to in the study of CRF performance?

<p>Nitrogen Application Efficiency (B)</p> Signup and view all the answers

Flashcards

Controlled-release fertilizer (CRF)

A type of fertilizer that releases nitrogen (N) at a controlled rate over time, matching crop needs.

Nitrogen (N) leaching

The movement of nitrogen from the soil into groundwater or surface water, often causing environmental problems.

CRF vs. Conventional Urea

CRF application significantly reduces nitrogen leaching compared to conventional urea application, with no crop yield loss.

Nitrogen Assimilatory Activity

The process plants use to absorb and utilize nitrogen.

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Glutamine synthetase activity

An enzyme crucial to Nitrogen Utilization; its activity correlates positively with N use efficiency in rice.

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N Efficiency

Using nitrogen efficiently to maximize crop yield without unnecessary waste.

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Urea-loaded cellulose hydrogels

A controlled-release fertilizer that improves Nitrogen use efficiency by holding nitrogen in a way that plants can easily absorb throughout the growing season.

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Rice crop optimal requirement

The exact amount of nitrogen needed for the highest rice yield.

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Nitrogen (N) treatments

Different levels of nitrogen applied as fertilizer.

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Grain yield

The total amount of rice produced.

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Optimum N rate (T4H)

The amount of nitrogen fertilizer that produced the highest rice yield (71% increase) compared to other applied treatments.

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Nitrogen Use Efficiency (NUE)

The amount of grain produced per unit of nitrogen applied.

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Harvest Index (HI)

The proportion of total aboveground plant biomass that is harvested grain yield.

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N agronomic efficiency (NAE)

The effect of Nitrogen on the yield of rice.

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Recommended Dose of Fertilizer (RDF)

The standard amount of fertilizer that is normally recommended for the crop.

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CRF hydrogel degradation

CRF hydrogels almost completely degraded after 135 days.

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CRF application advantage

CRF can be used as a single basal application, reducing the need for frequent dosing and lowering labor costs.

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Higher rice yield

CRF with 75% N had a 71% increase in yield compared to the control group.

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CRF N efficiency

CRF treatment showed the highest Nitrogen Use Efficiency (NUE).

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Reduced N losses

CRF application helps reduce nitrogen losses during rice cultivation.

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Basal application

A single initial application of fertilizer or treatment.

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Higher Nitrogen Accumulation Efficiency (NAE)

CRF treatment had the highest Nitrogen Accumulation Efficiency (NAE): 12.8kg/kg

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Study Notes

Eco-Friendly Cellulose Hydrogels as Controlled Release Fertilizer for Upland Rice

  • Cellulose hydrogels, a controlled-release fertilizer (CRF), were used to enhance upland rice growth and yield.
  • Nitrogen (N) treatments (30, 60, 90, 120 kg N ha⁻¹) were applied as CRF treatments, alongside a recommended dose of fertilizer (RDF) and a control group (0 N).
  • Applying CRF at the optimal N rate (T4H—90 kg N ha⁻¹) resulted in a 71% increase in grain yield.
  • This optimal N rate also increased panicle number, grains per panicle, and N uptake (0.25 g kg⁻¹).
  • The highest harvest index (HI) and N harvest index (NHI) were observed with T4H CRF at 45.5% and 67.9%, respectively.
  • Application of T4H CRF (75% N) gave higher yields than 100% N and 100% RDF treatments.
  • CRF application as a basal dose positively impacted growth and yield compared to split applications of conventional urea-based fertilizers.

Rice as a Staple Food

  • Rice is a staple food for over 3 billion people globally, providing 60-70% of energy needs in Asia.
  • Malaysia's rice self-sufficiency was around 70% from 2008-17, producing approximately 2.57 million tons in 2017.
  • Production decreased to 2.34 million tons in 2020.
  • Sarawak had a lower self-sufficiency level (38%) in 2017, importing from other countries. The Sarawak government targets raising rice self-sufficiency to 60% by 2030.
  • Efficient and proper fertilizer use contribute to increased production.
  • Current fertilizer practices show less than 50% plant uptake efficiency.

Experimental Details and Methods

  • The research used a pot experiment in a mini-greenhouse over a year (June-December 2022) in a rainforest climate in Sarawak, Malaysia.
  • The experiment used the Maswangi (MRQ74) rice variety, provided by Malaysian Agricultural Research and Development Institute (MARDI).
  • Six fertilizer treatments (T1-T6U) were applied in a completely randomized block design with 5 replications:
    • T1: 0 N (control)
    • T2H: 25% RDF
    • T3H: 50% RDF
    • T4H: 75% RDF
    • T5H: 100% RDF
    • T6U: 100% RDF in split applications.
  • Soil pH and total N were measured.
  • Rice was sown in pots, and urea was the source of nitrogen.
  • Irrigation and manual weeding were conducted.
  • Measurements included plant height, number of tillers, chlorophyll content (SPAD readings), yield components (grains, harvest index, 1000-grain weight), and nitrogen uptake.

Plant Growth and Yield Parameters

  • Plant height, number of tillers, and chlorophyll content increased steadily over time until maturity (130 days after sowing).
  • T4H (75% N) consistently outperformed other treatments in most growth parameters.

Nitrogen Uptake and Efficiency

  • T4H showed the highest nitrogen uptake, leading to better nitrogen use efficiency (NUE) and agronomic efficiency (NAE) compared to other treatments.
  • Correlation analysis demonstrated a strong link between grain yield, the number of grains per panicle, and the number of panicles.
  • Increased nitrogen uptake contributed to higher grain yield.

Conclusion

  • Moderate N application (T4H) in the form of controlled-release fertilizer (CRF) resulted in significant yield increases and improvements in various growth parameters and efficiency metrics compared to conventional urea application. Increased panicle numbers, grains per panicle, and grain yield supports this finding.

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