# 6.4: Summative Assessment- N and P Balances

$$\newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} }$$ $$\newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}}$$$$\newcommand{\id}{\mathrm{id}}$$ $$\newcommand{\Span}{\mathrm{span}}$$ $$\newcommand{\kernel}{\mathrm{null}\,}$$ $$\newcommand{\range}{\mathrm{range}\,}$$ $$\newcommand{\RealPart}{\mathrm{Re}}$$ $$\newcommand{\ImaginaryPart}{\mathrm{Im}}$$ $$\newcommand{\Argument}{\mathrm{Arg}}$$ $$\newcommand{\norm}[1]{\| #1 \|}$$ $$\newcommand{\inner}[2]{\langle #1, #2 \rangle}$$ $$\newcommand{\Span}{\mathrm{span}}$$ $$\newcommand{\id}{\mathrm{id}}$$ $$\newcommand{\Span}{\mathrm{span}}$$ $$\newcommand{\kernel}{\mathrm{null}\,}$$ $$\newcommand{\range}{\mathrm{range}\,}$$ $$\newcommand{\RealPart}{\mathrm{Re}}$$ $$\newcommand{\ImaginaryPart}{\mathrm{Im}}$$ $$\newcommand{\Argument}{\mathrm{Arg}}$$ $$\newcommand{\norm}[1]{\| #1 \|}$$ $$\newcommand{\inner}[2]{\langle #1, #2 \rangle}$$ $$\newcommand{\Span}{\mathrm{span}}$$

## Introduction

The last page of module 5.2 mentions the twin issues of deficit and surplus that are principal challenges in the management of soil nutrients. The exercise in this summative assessment requires you to use real data on nutrient inputs and outputs from two systems to create nutrient balances, and then analyze the situation of nutrient balance or surplus. These systems are the Ohio River sub-basin of the Mississippi River basin and measurements of nutrient flow from hillside farming in the Bolivian Andes. You should do this activity with a partner or small group in class, and prepare to discuss your results with the class. You will use data from a table to answer questions on the assessment worksheet (download below).

In analyzing the twin issues of nutrient surplus and nutrient shortage in soils and food production systems, you'll be practicing a geoscience "habit of mind" of systems thinking. In other words, to examine the wider impacts of nutrient management or the causes of soil infertility, we need to expand our focus from a single field to a landscape or river basin and think about a web of linkages between farmers, nutrient supplies, economic factors, and watersheds, among other system components. This allows us to contemplate these challenges in the proper frame and over the right timescale.

Download the worksheet to complete and turn in your assessment. The worksheet contains information in a table that you will need to complete the assignment.