Indicators and considerations for sustainable winter cereal production systems in the Overberg
Date
2021-12
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Publisher
Stellenbosch : Stellenbosch University
Abstract
ENGLISH SUMMARY : The world’s population has been steadily increasing and is projected to reach 9.7 billion people in 2050. This necessitates a proportional increase in food production which will place increased pressure on natural resources which may lead to further environmental degradation. Therefore, there is an urgent need for more sustainable food production methods. Conservation agriculture (CA) has been put forward as one of the most holistic methods of sustainable agricultural intensification.
There are three main principles associated with CA, namely minimal or no-tillage, permanent organic soil cover and the use of crop rotations. This study was focused mainly on the crop rotation aspect of CA. The main objective for this study was to determine the extent to which identified critical drivers promote the long-term sustainability of different crop rotation systems for the Middle Rûens area of the Overberg. The most profitable crop rotation systems were identified and the physical and biological factors underpinning this profitability were discussed. This study focused only on short crop rotation systems although longer rotation systems are also used in the Overberg area.
This study used existing crop rotation trial data from Tygerhoek Experimental Farm in the Overberg which was managed according to CA principles. Four main rotation systems were considered, three of which consisted of a mix of cash crops and pastures, with one system having only cash crops. Wheat, barley and canola were the main cash crops focused on in this study. Data was collected from these trials from 2002 to 2020 and included climatic data, soil analysis data, all input costs, yields and prices of crops for each year as well as all livestock information. The data was separated into two main sections for analysis, namely the ecological data (yield and quality) and the economic data (gross margins and input costs).
The inclusion of pastures in crop rotation systems increased yields and thereby increased gross incomes for the specific systems. The system containing only cash crops had consistently lower yields and higher allocatable variable costs than the other three systems. This resulted in the systems including a pasture component having higher gross margins on average when compared to the continuous cash cropping system. Climatic conditions, cultivar choice and soil type were important determining factors when it came to both crop yield and quality. The resiliency of the systems to drought also improved over time as the yields recovered quickly after particularly dry years, such as 2019.
The three most substantial input costs for all systems were fertiliser, weed control and seed. Fertiliser costs were shown to decrease towards the end of the trial for the systems including pastures, but not for the cash cropping system. Weed control and seed costs were also higher in the continuous cash cropping system than in the other three systems. The total input costs for the systems including pastures also decreased towards the end of the trial, unlike those for the cash cropping system.
Profitability underpins the long-term sustainability of the short-rotation systems and understanding the drivers of this profitability is a necessity.
AFRIKAANSE OPSOMMING : Geen opsomming beskikbaar.
AFRIKAANSE OPSOMMING : Geen opsomming beskikbaar.
Description
Thesis (MSc)--Stellenbosch University, 2021.
Keywords
Winter grain -- Overberg (South Africa), Crop rotation -- Overberg (South Africa), Sustainable agriculture -- Overberg (South Africa), Cover crops -- Overberg (South Africa), UCTD