CSPP221 Unit 8 - Intercropping Lecture Notes PDF

Faculty of Natural and Agricultural Sciences School of Geo and Spatial Sciences Programme: BSc Agriculture CSPP221 – 12 credits Module Name: Introduction into Agronomy LECTURE 9 – Intercropping Study Unit 8 Intercropping Learning outcomes  On the completion of this unit, the learner will:...

Faculty of Natural and Agricultural Sciences School of Geo and Spatial Sciences Programme: BSc Agriculture CSPP221 – 12 credits Module Name: Introduction into Agronomy LECTURE 9 – Intercropping Study Unit 8 Intercropping Learning outcomes  On the completion of this unit, the learner will:  Be able to describe and explain types of intercropping.  Be able to explain the advantages and disadvantages of intercropping.  Be able to describe the factors to consider when planning intercropping system.  Reading material ❑ Maitra, Sagar, et al. "Intercropping—A Low Input Agricultural Strategy for Food and Environmental Security." Agronomy 11.2 (2021): 343. Introduction ❑ Intercropping is a multiple cropping system, in which two or more crop species are planted simultaneously in the field during a growing season. ❑ The component crops are neither seeded at the same time nor harvested, but they remain simultaneously in the field for a major portion of the growth periods. ❑ Intercropping is generally comprised of the main crop and one or more companion crops, where the production of the main crop is the prime goal. ❑ Intercropping is the value addition of the cropping system which can ensure higher productivity, efficient use of resources, and more income Concepts of intercropping ❑ In intercropping, basic ecological principles are observed in the form of above and below ground diversity, competition and facilitation for production of crops ❑ Intercropping can be: ▪ Annual plants with annual plants intercrop. ▪ Annual plants with perennial plants intercrop. ▪ Perennial plants with perennial plants intercrop. Types of intercropping Row intercropping: raising of one or more crops sown in regular rows, and growing intercrops in a row or without row at the same time. The row intercropping is a usual practice targeting maximum and judicious use of resources and optimization of productivity Mixed intercropping: growing two or more crops simultaneously with no row arrangement/definite row proportion. This type of intercropping can be suitable for grass-legume intercropping in pasture.  Types of intercropping 3. Strip intercropping: growing two or more crops simultaneously in different strips wide enough to permit independent cultivation but narrow enough for the crops to interact. Strip intercropping is known to enhance radiation use efficiency in marginal and poor lands 4. Relay intercropping: growing two or more crops simultaneously during part of their life cycles. ▪ A second crop is planted after the first has reached its reproductive stage, but before it is ready for harvest.  Crop Geometry in Intercropping ❑ Refers to the percent of plant population maintained for each crop in intercropping system. It determines the advantage or disadvantage of intercropping. The pant population of each crop is compared to pure stands of the respective crops. There are two categories as follows: 1. Additive series ▪ In this system, the main crop is sown at 100% of its recommended population in pure stand which is known as the base crop and another crop known as intercrop (component crop) is introduced into the base crop by adjusting or changing crop geometry. ▪ The crop sown with 100 per cent density as seeded in the pure stand is called ‘base crop’ and another crop is termed as ‘intercrop’. ▪ In this system, ‘intercrops’ are sown within the row space of the ‘base crop’ and sometimes planting geometry of the base crop is modified to create space for intercrops (for example, paired row planting). ▪ The proportion of ‘intercrop’ (not base crop) mostly remains less than its optimal population in sole cropping. Crop Geometry in Intercropping 2. Replacement series ▪ In this system of intercropping, both the crops are called component crops. ▪ one component crop is introduced by the replacement of the other crop. ▪ In the replacement series of the intercropping system, no crop is sown with its fullest population as seeded in respective sole cropping.  Advantages of intercropping 1. Increase production ❑ High yield production compared to sole cropping on the same land. ❑ Intercropping is an economic method for higher production with lower levels of external input Effect of oat-vetch bicultures on final cover crop dry weight at termination in 2009 and 2010 winter seasons.  Advantages of intercropping 2. Greater use of environmental resources ❑ Comes through the interaction between components in intercrops and the difference in competition for the use of environmental resources ❑ Complete use of above space: ❑ Better use of below space: Advantages of intercropping 3. Reduction of pest, diseases and weed damage ❑ The diverse ecosystem offered by intercropping breaks up the cycles of diseases and pest ❑ A range of shelters and food can be provided for the predators and parasites by intercropping ❑ Plant pests and diseases get less chance to spread quickly 4. Stability and uniformity yield ❑ Risk of agronomy failure in multi cropping system is lower than in pure cropping system. Advantages of intercropping 5. Improve soil fertility and increase in nitrogen. ❑ Rhizobium bacteria are able to have a symbiotic relationship with plants of leguminosae family and thereby can fix atmospheric nitrogen into available nitrogen for the plants uptake. ❑ As a result, nitrogen element for soil fertility and plant growth is added to the soil. ❑ There is less soil erosion with intercropping due to increased cover and soil being sheltered from the impact of wind and raindrops. Benefits of intercropping system (Maitra et al. 2021)  Potential problems with intercropping 1. Adverse interference ❑ Competition ▪ There are two types of competition between plants: intraspecific competition and interspecific competition. ▪ Intraspecific- o The competition for resources between organisms (e.g. plants and animals) of the same species. o For example, between two Zea mays plants. ▪ Inter-specific o The competition for resources between organisms of different species. For example between Zea mays and Phaseolus vulgaris. o In row crops there are also intrarow (or intrahill competition between plants within a row (or hill) and interrow (or interhill) competition between plants in different rows (or hills). ▪ A plant disadvantaged in light capture will have a low photosynthetic rate, leading to poor root development and therefore becoming disadvantaged in nutrient capture. Such a plant may die when competition is intense.  Potential problems with intercropping 1. Adverse interference ❑ Allelopathy ❑ Some plants may interfere with the growth of others ❑ Allelopathy is a situation where chemical substances, released from a plant or its residue, affect growth of the neighbours. 2. Mechanization ❑ When machines are used for weeding or harvesting, intercropping can be difficult. ❑ Strip intercropping is a useful solution to this problem. Potential problems with intercropping 3. Labor ❑ Labor requirement of an intercropping system may be higher than in sole cropping as two or more different crops are planted at the same time or shortly after one another. 4. Difficulties in management ❑ Differences in fertiliser and herbicide management ❑ Decision on relative proportion of component crops (additive and substitutive designs) ❑ Cultivar selection and spatial arrangement  Factors to consider when initiating intercropping 1. Climate ❑ The best design of an intercropping system depends on the specific conditions and climate. e.g. rains throughout year, dry period, very short rainy season. 2. Crop choice ❑ Chosen crops should not compete for resources (physical space, nutrients, water, light) and peak demand should not coincide Factors to consider when initiating intercropping 3. Plant densities ❑ The two main factors that determine the yield of an association are: ▪ Proportion of species in the mixture ▪ Populations of the species ❑ To optimize plant density, the seeding rate of each crop in the mixture has to be adjusted below its full rate ❑ The challenge is knowing how much to reduce the seeding rates and the best way to find out the optimal plant densities is to experiment with different seeding rates.  Factors to consider when initiating intercropping 4. Planting and maturity dates ❑ Adaptation in the planting dates of the different crops in an intercrop can help to reduce competition and maximize yield. ❑ Staggered maturity dates or development periods takes advantage of variations in peak resource demand for nutrients, water and sunlight ❑ Different maturity dates also assist in staggered harvesting and separation of grain commodities  Factors to consider when initiating intercropping 5. Plant architecture ❑ Architecture is used strategically to allow one member of the mix to capture sunlight that would not otherwise be available to the others ▪ Can use wider spacing of taller component ▪ Can select for leaf display that allows in more sunlight (planophiles versus erectophiles) ▪ E.g. The tall maize crops should be planted in rows far enough apart to allow sunlight to reach the smaller groundnut plants.  Evaluation of intercropping systems ❑ Important indices that are used to evaluate multiple cropping systems are: ▪ Land equivalent ratio (LER) ▪ Area time equivalent ratio (ATER) ▪ Multiple cropping index (MCI) ▪ Monetary value Evaluation of intercropping systems Land equivalent ratio ❑ Most frequently used to judge the effectiveness of an intercrop system ❑ To calculate LER, the intercrop yields are divided by pure stand yields for each component crop in the intercrop. ❑ The two figures are added together. ▪ When an LER measures 1.0, it tells us that the amount of land required for intercrops is the same as that for the sole crops ▪ LERs above 1.0 shows an advantage to intercropping while numbers below 1.0 show a disadvantage to intercropping ▪ LER of 1.25 tells us that the yield produced in the total intercrop would have required 25% more land if planted in pure stands ▪ If the LER is 0.75 then we know the intercrop yield was only 75% of that of the same amount of land that grew pure stands  Evaluation of intercropping systems Area time equivalent ratio ❑Suitable for crops with different maturity ❑Modification of LER, which takes into account the time it takes a crop in the field ❑Allows evaluation of intercrop yield per unit area per unit time  Evaluation of intercropping systems Monitory evaluation ❑ Only acceptable if all intercrop products are marketable cash crops ❑Provides a common factor for comparison of component crops ❑Labour is treated as a variable cost  Evaluation of intercropping systems Other measures ❑ Nutritional evaluation ▪ Energetics ❑ Farmer evaluation ▪ Labour ▪ Biomass for livestock END