SAS Quiz 3

Nitrogen uptake effect on rice yield

Yield increases with nitrogen uptake, but plateaus at about 150 kg/ha

Problem with excess nitrogen in soil

It is not used by plants and has the potential to run off into rivers and eventually the ocean

Sources of nitrogen for soil

N-fixing crop rotation (e.g., corn and soybean), Natural Chilean nitrate, Cover crops and manures, Haber/Bosch ammonia synthesis

Haber/Bosch ammonia synthesis

Produces 82 million tons N/year from natural gas

World population support without Haber-Bosch

Only 3-4 billion people

Sufficiency of animal manures for crop nitrogen demands

Supply is insufficient to meet current crop nitrogen demands

World average daily caloric intake per capita (approx. 2011)

About 2,800 Cal per person per day

Relationship between a country's GDP and food availability

Not a straight line relationship. People in countries with very low GDPs see a drop in available calories

U.S. Dietary Energy Supply (food available) per person/day, 2011

3,688 Cal (Plant 73% / Animal 27%)

U.S. diet composition shift (1967 vs 2011)

More processed foods (refined grains, vegetable oils, corn syrup) and less beef, but more poultry

Dietary Energy Supply (DES)

Represents food available for consumption, not necessarily what is eaten (it doesn't subtract waste

Food energy wasted in the US

27-30% (lost at transport, retail, food service, and consumer level)

Staple food

One that is regularly consumed in large quantities as to form the basis of a traditional diet and serves as a major source of energy and nutrients

Fodder crops

Crops that are cultivated primarily for animal feed

Why cereals/grains are so widely planted

High energy density ($\sim$3.6 Cal/g, 5X tubers) and high protein (10% of cereals, 5X tubers)

The three most important crops in the world

Maize, rice, and wheat

Main staple crop in the Democratic Republic of Congo

Cassava

Relationship between GDP per capita and starchy staples

The higher the GDP per capita, the lower the percentage of starchy staples in the diet (more varied diet)

Grains and tubers (Pre-industrial vs. Western diet)

Pre-industrial: 2/3 of diet; Western: <1/3

Fats (Pre-industrial vs. Western diet)

Pre-industrial: 10% of all calories; Western: >40%

Fiber Intake (Pre-ag vs. Pre-industrial vs. Western)

Pre-ag: >100 g/day; Pre-industrial: 50 g/day; Western: <20 g/day

U.S. average salt (NaCl) intake vs. recommendation

Avg: 9 g/day; Recommendation: not to exceed 2.3 g Na/day

Primary source of salt in U.S. diet

76% in processed foods

U.S. per capita sugar consumption (1700 vs. Today)

1700: 4 pounds/year; Today: 150 pounds/yea

Western lifestyle diet characteristics

A high caloric, low fiber, high salt, fatty diet with a high intake of simple sugars

Type-2 diabetes

Pancreas becomes exhausted and blood glucose rises

Plant food diversity statistic

7,000 plants have been used as food, but 15 produce more than 90% of all food

CAFOS

Concentrated animal feeding operations.

World Meat Production Trend

World meat production and consumption continue to increase

Broilers vs. Layer

Broilers are chickens that we eat (slaughtered @ 6 weeks). Layers are the ones that produce eggs (commercially good for 1-2 years).

Global Meat Production by Type (2023)