Unit 4: Fertilizer Sampling - Practice Quiz

1 What is the main purpose of fertilizer sampling?

2 What is an increment in fertilizer sampling?

3 What is formed by combining several fertilizer increments?

4 Which tool is commonly used to collect samples from fertilizer bags?

5 How should bags be selected from a large fertilizer lot for routine representative sampling?

6 Where should increments be collected from a bulk fertilizer pile?

7 Which method reduces a large fertilizer sample by dividing it into four equal parts?

8 During quartering, which portions are usually combined after the sample is divided into four parts?

9 What is the purpose of a riffle divider in fertilizer sampling?

10 Why should fertilizer sampling tools be clean and dry?

11 Which container is most suitable for a fertilizer sample that can absorb moisture?

12 Which information should be written on a fertilizer sample label?

13 What is a fertilizer lot?

14 Why are multiple increments collected from a fertilizer lot?

15 Before reducing a composite fertilizer sample, what should generally be done?

16 What is the laboratory sample?

17 What is the most likely result of collecting a sample from only one point in a large fertilizer lot?

18 Why should a sample container be sealed promptly after fertilizer sampling?

19 What should be done between sampling two different fertilizer lots?

20 Which practice helps protect a worker while sampling dusty fertilizer?

21 A fertilizer inspector must sample a lot containing 80 sealed bags stored in several rows. Which approach is most likely to produce a representative sample?

22 Before using a sampling probe to collect fertilizer from sealed bags, what action is most important for preventing contamination?

23 A probe is inserted only into the top layer of each fertilizer bag. What is the main sampling problem with this procedure?

24 Ten equal incremental samples, each weighing g, are combined. What is the mass of the resulting gross sample?

25 A well-mixed gross sample is too large for laboratory analysis. Which method best reduces its mass while preserving representativeness?

26 During coning and quartering, which two quarters should normally be retained after the flattened sample is divided into four equal parts?

27 Which device is most suitable for repeatedly dividing a free-flowing granular fertilizer sample into representative portions?

28 Granular fertilizer is moving continuously on a conveyor belt. Which sampling method gives the most representative increment?

29 A bulk fertilizer pile has visible zones of different particle sizes. What should the sampler do?

30 Why are equal-mass increments generally preferred when forming a composite sample from equivalent units in a fertilizer lot?

31 A hygroscopic fertilizer sample is left in an open paper bag before moisture analysis. What is the most likely effect?

32 Which container is most appropriate for transporting a fertilizer sample that readily absorbs moisture?

33 A sampler collects increments from every tenth bag, but the bags were stacked in a repeating production sequence. What is the main risk?

34 A delivery consists of two fertilizer grades stored separately. How should the material be sampled for compliance testing?

35 What is the primary purpose of thoroughly mixing incremental samples before reducing the gross sample?

36 A fertilizer lot contains bags. If bags are selected and one g increment is taken from each, what is the gross sample mass?

37 Which practice best supports traceability after a fertilizer sample has been collected?

38 A sample seal is broken when the laboratory receives it. What is the most appropriate response?

39 Fine particles settle toward the bottom of a sample container during transport. What should be done before taking the test portion?

40 Two sampling plans collect the same total sample mass. Plan X takes a few large increments, while Plan Y takes many smaller increments spread across the lot. Which plan generally gives better representation of a heterogeneous lot?

41 A 40-tonne bulk fertilizer lot consists of four physically identifiable strata. Strata masses and estimated standard deviations of nutrient concentration are 10 tonnes and 1.0%, 15 tonnes and 2.0%, 10 tonnes and 3.0%, and 5 tonnes and 4.0%, respectively. If 40 increments are allocated by Neyman allocation with equal sampling cost, which allocation is most appropriate?

42 A conveyor carries fertilizer with a periodically varying composition caused by a granulator cycle of exactly 12 minutes. An increment is taken every 12 minutes after one randomly selected starting time. What is the principal sampling risk?

43 During loading, fertilizer flow varies substantially with time. Equal-mass increments are collected at equal time intervals and combined without weighting. Which lot characteristic does the resulting composite most directly estimate?

44 A cross-stream cutter samples a falling fertilizer stream. Which design most directly supports an unbiased increment when particle size and velocity vary across the stream?

45 A sampling spear reaches the full depth of each fertilizer bag, but its slots open sequentially from the handle end toward the tip while the spear is being withdrawn. Which error is most likely?

46 A lot contains 1,000 bags: 900 bags contain fertilizer averaging 20% nutrient and 100 bags contain fertilizer averaging 30%. A sampler takes equal increments from 10 bags in each group and combines all 20 increments equally. What does the composite estimate if no weighting is applied?

47 A representative composite sample is reduced from 16 kg to 1 kg by repeated riffle splitting. After four ideal splits, which statement is correct?

48 A composite contains coarse nutrient-rich granules and fine nutrient-poor particles. Before laboratory reduction, the sample is poured into a cone and divided into quarters once. Which modification most effectively reduces segregation bias?

49 A 2 kg laboratory sample contains nutrient-rich granules of 4 g each at a mean frequency of one granule per 100 g. The sample is reduced to a 50 g test portion without grinding. Why can the reported nutrient result remain highly variable even after perfect mixing?

50 Two sampling plans use the same total collected mass. Plan X collects 40 increments of 100 g across the lot; Plan Y collects 4 increments of 1 kg from nearby locations. When lot heterogeneity is mainly spatial, which conclusion is most defensible?

51 A fertilizer lot is arranged in a bag grid. A sampler chooses a random starting bag and then samples every 20th bag from a row-wise numbered list. Bags from different production batches occupy complete rows. What is the main flaw?

52 A liquid fertilizer tank has settled solids containing much of the phosphorus. The tank is circulated for five minutes, after which a sample is drawn from a top valve. Which evidence is most important before treating the sample as representative?

53 A hygroscopic fertilizer is sampled for moisture determination. The composite remains for 30 minutes in an open tray during mixing and reduction. What is the best corrective approach for future sampling?

54 A sampler must estimate the mean nutrient concentration of a bulk pile, but only the exposed surface is accessible and the pile is known to have segregated during stacking. Which conclusion is technically justified?

55 Duplicate field composites differ substantially, while duplicate laboratory analyses from each composite agree closely. What is the most likely dominant source of uncertainty?

56 A lot is sampled using 25 increments. The estimated standard deviation among independent increment concentrations is 5 percentage points. Ignoring finite-population correction and analytical error, what is the approximate standard error of the unweighted composite mean?

57 A batch consists of bags with unequal masses. The goal is to estimate nutrient concentration per unit mass for the entire batch. Which bag-selection rule best supports an unbiased estimate when equal-mass increments are taken from selected bags?

58 A sampler collects increments correctly but transports the composite in a half-filled container that is repeatedly vibrated. Before taking the laboratory test portion, which action is essential?

59 An automatic sampler takes one increment whenever each 500 kg of fertilizer passes a mass-flow meter. The meter later proves to read 10% high at all flow rates, but its error is stable and sampling spans the complete lot. What is the most likely effect on the estimated mean composition?

60 A fertilizer shipment contains an early 80-tonne portion and a late 20-tonne portion. Their mean nutrient concentrations are 18% and 28%, respectively. Separate representative composites are obtained from both portions. How should they be combined to estimate the shipment mean?