Crop Rotation

This note looks at crop rotation as one of the sustainable arable crop production practices. It describes the approaches to crop rotation, the benefits and the limitations of crop rotation. The note will serve as a valuable resource for higher ed students taking introductory courses in Agriculture.

1. Arable Crop production Topic 4 Crop Rotation Daisy Odunze

2. Learning Outcomes Define crop rotation. Differentiate crop rotation from mixed cropping. Describe the two common approaches to crop rotation. Outline the steps a farmer takes in planning for crop rotation. Apply the principles of crop rotation in developing the crop rotation plan. Develop a simple crop rotation plan using the two approaches described. Discuss the benefits, limitations and challenges of crop rotation. Explain why soil preparation is necessary in arable crop production. Suggest different types of farm machineries used in preparing soil for planting.

3. Introduction Crop rotation refers to the practice of planting different crops on the same plot in a sequential order over a period of years. It is the opposite of monoculture (growing the same crop in the same plot year after year). It is not the same as mixed or intercropping (the practice of growing two or more crops together on the same piece of land). Year 1 Year 2 Year 3 Year 4 Plot 1 Crop A Crop B Crop C Crop A

4. Simple or Complex Crop Rotation Simple Crop Rotation Involves growing 3 to 4 crops successively usually for three to four years. Alternating two crops is the simplest crop rotation. Complex Crop Rotation Five to eight years crop rotation plan involving more than half a dozen crops. The higher the number of years and crops involved, the more complex the crop rotation system becomes.

5. Why Rotate Crops? Growing the same crop in the same plot year after year leads to : Imbalance of the soil nutrient composition as certain nutrients gets depleted while others build up depending on the requirements of the crop. Build up of soil-borne pest and diseases with the continual growth of a single crop. Poor soil structure leading to low yield Crop rotations are an important part of any sustainable agricultural system.

6. Principles of Crop Rotation To achieve desired objectives from crop rotation the following principles are important; A minimum of three to four years before replanting the same crop on the same plot of land. Crops of the same family should not follow each other. Deep rooted crops (sweet potato) to follow shallow rooted crops (maize). Leguminous crops (beans or peas) to follow high-nitrogen demanding crops (potatoes). Non-exhaustive crops (cowpea) to follow exhaustive crops(eggplant).

7. Principles of Crop Rotation Cont’d For sloppy plots, crops which promote erosion (maize / sorghum) should be followed by crops that are erosion resistant (clover). In regions with limited rainfall and irrigation facilities, high-water demanding crops should be followed with low water demanding crops. Weed suppressing crops to follow weed susceptible crops. Plant non-host plants for a year or two if nematodes become a problem.

8. Approaches to Crop Rotation There are two main approaches to crop rotation: Rotating crops by edible parts. Rotating by crop families. Rotation by Edible Parts Farmers can rotate their crops according to edible parts, but this approach has one major drawback. Plants of the same family but different edible parts tend to suffer from the same soil-borne pests and diseases and absorb same nutrient from the soil.

9. Approaches to Crop Rotation Cont’d For example, tomatoes and potatoes are both from the Solanaceae family but have different edible parts. Under this system, tomatoes will be classified as fruit and potatoes as roots. Planting potatoes after tomatoes against the principles of crop rotation . Figure 1: Crop rotation by edible parts. Source: https://www.theseasonalhomestead.com (2019)

10. Approaches to Crop Rotation Cont’d Rotation by Crop Families Allows grouping of plants with similar maintenance requirements together and helps reduce the risk of unintentionally passing on crop-specific soil-dwelling pests and diseases to the next crop. Figure 2: Crop rotation by crop family. Source: https://www.theseasonalhomestead.com (2019)

11. Steps in Crop Rotation Planning crop rotation involves the following steps presented in the figure below.

12. Benefits of Crop Rotation Reduces dependence on fertilizer use. Enhanced soil fertility. Increased crop yield and variety. Less fallow periods. Enhanced productivity of successive crops. Resource utilization. Better soil structure. Improves overall soil quality. Means of erosion Control Natural pest and disease control. Reduces weed stress. Diversification of risks.

13. Limitations and Challenges of Crop Rotation. Limitations Does not allow for specialization of production. Calls for higher investment in machinery. More demand on time. Higher demand on labour . Opportunity cost. Risky. Challenges Choice of crops depends on several fixed factors (soil type, topography, climatic conditions, water availability) and variable factors (demand, labour ). Planning can be difficult given these factors. Improper implementation of crop rotation can lead to more harm than good.

14. Farm Machineries for Preparing Soil for Arable Crop Production Preparing or getting the ground ready for arable crop production involves: clearing unwanted vegetations and weeds, ploughing to dig up and overturn the soil, harrowing to break up soil and incorporate plant residues, and leveling and smoothing the soil surface. These activities entail the use of the tractor and different soil cultivation machineries and they include the following:

15. Farm Machineries for Preparing Soil for Arable Crop Production Tractor : used to propel the plough, harrow and other implements. Plough : used to cut, granulate, and invert the soil, creating furrows and ridges. Harrow : used to break up soil lumps and improve soil granulation and surface uniformity to make it suitable for seeding and planting operations. Cultivator : used for pulverizing the soil before planting. The cultivator stirs the soil to a greater depth than the harrow. Cultipacker : used to crush dirt clods, removes pockets of air and press down stones to form a smooth firm seedbed. Rotary tiller : motorized cultivator with rotary blades used for tilling the soil. It is also known as a rotavator.

16. Conclusion Crop rotation is widely acknowledged as necessary for improving soil quality and maintaining farm productivity. The principles, approaches, and process are foundations for successful cropping systems and the benefits attest to that. Soil preparation is essential for the success of all other activities involved in arable crop production and therefore should be carried out with utmost care.

17. Questions

18. The end Question? Thank you

19. Group Work Plot a four-year crop rotation plan for a small vegetable farm using worksheet provided, taking into consideration the principles guiding the process. Describe the crop rotation approach used. Refer to the table on crop botanical families for guidance.

20. Further Reading Watch the video on crop rotation by GrowVeg.com. Available at https://youtu.be/XeNA6XdMoF 8 Read the attached PDF note on this topic. Read the SlideShare note on farm machineries for soil preparation. Available at https://www.slideshare.net/victoriamoyapichardo/soil-preparation-tools-and-implements Study the table for the crop botanical families attached to the word document note as appendix.

21. Reference The Seasonal Homestead. (2019). Crop rotation idea for an organic vegetable garden .[Online] Available at https://www.theseasonalhomestead.com/crop-rotation-basics organic-vegetable-garden/ . [Accessed 26/05/2020].

22. Table 1: Common Crop families for crop rotation Family Name Common name Crops Alliaceae Onion family Onion, garlic, shallot, leek, chives, asparagus. Apiaceae Carrot family Carrot, celery, parsley, cilantro, dill, fennel, parsnips Brassicaceae Cabbage family Brussels sprouts, broccoli, cabbage, cauliflower, kale, turnip, kohl-rabi, oriental greens, radish. Chenopodiaceae Beetroot family Spinach, beetroot, Swiss chard Cucurbitaceae Marrow family Courgettes, squash, zucchini, marrows, melon, pumpkin, cantaloupe, cucumber. Fabaceae Legume family Peas, broad beans, butter beans, kidney beans, French and runner beans, lentils, cow pea, soybean, alfafa . Poaceae Grass family Wheat maize, rice, oat, barley, sorghum, rye Solanaceae Nightshade family Potato, tomato, pepper, eggplant. Others; Asteraceae Convolvulaceae Malvaceae Aster family Morning glory family Mallow family Non-annual rotation crops used for plugging gaps in the plots that do not suffer adversely from any soil-borne pest and disease and can be fitted anywhere. E.g. lettuce, Sweet potato, okra.