Types and Benefits of Organic Materials in Integrated Nutrient Management

Healthy soil is the foundation of productive farming – and nowhere is this more critical than in rainfed agriculture, where farmers cannot compensate for poor soil fertility with heavy irrigation. In these systems, building and maintaining soil health depends almost entirely on what is added back to the land. Organic materials – from farmyard manure and compost to green manures and industrial by-products like press mud – are the backbone of this effort. Used as part of an integrated nutrient management (INM) approach, they release nutrients gradually, improve soil structure, stimulate microbial life, and reduce farmers’ dependence on costly chemical fertilizers. This post explains the major types of organic materials used in INM and why each one matters.

What are organic materials in integrated nutrient management? 🔗

Integrated nutrient management combines organic, inorganic, and biological sources of nutrients to maintain soil fertility sustainably. Organic materials form the cornerstone of this approach. Unlike synthetic fertilizers, which deliver nutrients in soluble, fast-release forms, organic materials build soil health over time. According to the Livestock and Poultry Environmental Learning Community, organic carbon from manure energizes the soil microbial ecosystem, stabilizes nutrients, and makes them steadily available to crops – a function that no chemical fertilizer can replicate. The range of organic materials available is wide, and each has a distinct nutrient profile and mechanism of action.

Farmyard manure (FYM) 🔗

Farmyard manure is one of the oldest and most widely used organic inputs in agriculture. It is a mixture of cattle dung, urine, bedding material (usually straw), and remnants of fodder. FYM supplies the three primary macronutrients – nitrogen (N), phosphorus (P), and potassium (K) – alongside essential micronutrients.

Research compiled by the Livestock and Poultry Environmental Learning Community shows that organic nitrogen in manure is stored in an organic form that is slowly released as soils warm and as crops require it, resulting in far less leaching potential compared to synthetic nitrogen fertilizers. This slow-release property is especially valuable in rainfed systems where heavy rainfall events can wash away soluble nitrates. FYM also improves soil structure by increasing water infiltration and water-holding capacity, and studies suggest it can reduce soil erosion by 13-77% compared to unamended soils.

Compost 🔗

Compost is decomposed organic matter – produced from kitchen waste, crop residues, garden clippings, or animal manures – that has been stabilized through a controlled microbial process. It is not simply aged material; as Certified Naturally Grown explains, proper composting requires managed conditions of moisture, oxygen, temperature, and carbon-to-nitrogen (C:N) ratio to produce a finished, humus-like product.

The nutrient availability in compost is more gradual than in raw manure. NDSU Extension notes that research has found only about 15% of total nitrogen in beef feedlot compost is plant-available in the first year, with additional mineralization continuing into the second year. This gradual release reduces the risk of nutrient leaching and over-application. Compost also suppresses soil-borne diseases, improves porosity and water-holding capacity, and introduces beneficial microorganisms into the soil.

Poultry manure 🔗

Poultry manure, the droppings of chickens and other birds, is among the richest animal-based organic fertilizers available. It contains nitrogen, phosphorus, and potassium in higher concentrations than cattle manure, with a typical nutrient composition of around 0.9% N, 0.8% P, and 0.5% K.

A two-year field experiment published in Scientific Reports found that poultry manure significantly reduced soil bulk density, improved porosity and moisture content, and increased maize yield – with an application rate of 10 tonnes per hectare producing the best outcomes. The study underscored poultry manure’s potential as a sustainable soil amendment, especially in sandy loam soils with poor fertility. One important note: fresh poultry droppings are too concentrated to apply directly to most crops and should be composted first to reduce the risk of burning seedling roots and introducing pathogens.

Oilcakes 🔗

Oilcakes are the solid residues left after oil is extracted from seeds such as groundnut, mustard, neem, castor, and cottonseed. They are classified into two groups: edible oilcakes (e.g., groundnut, sesame), which can also serve as animal feed, and non-edible oilcakes (e.g., neem cake, castor cake), which are used directly as fertilizers.

Agricultural science notes from Rajasthan Agriculture University describe oilcakes as quick-acting organic manures that begin to nitrify within 30-45 days of application. Their decomposability increases as oil content decreases, and grinding the cakes into fine powder speeds up this process. Neem cake in particular is valued not only for its N-P-K content but also for its natural pest-repellent properties, helping to reduce soil-dwelling pests alongside improving fertility.

Press mud 🔗

Press mud (also called filter cake or mill mud) is a by-product of the sugarcane processing industry, generated when cane juice is clarified to produce raw sugar. For every 100 tonnes of sugarcane crushed, approximately 3 tonnes of press mud are produced as a by-product.

Research published through HAL open science shows that press mud contains around 21% organic carbon along with macro- and micronutrients. Its application enhances phosphorus availability, increases cation exchange capacity (CEC) for up to 30 months, and the residual effect on soil persists for up to four years. Press mud also benefits alkaline soils: sulphitation-process press mud contains calcium sulphate, which acts as a soil amendment for high-pH conditions. A PLOS ONE study further confirmed that press mud can function as both a biofertilizer and a biostimulant – replenishing soil microorganisms and organic carbon depleted by erosion or field burning.

Pig manure 🔗

Pig manure is a nutrient-rich organic material, broadly comparable to other livestock manures in its N-P-K content. A comprehensive review of livestock manure impacts on soil health published in Soil Systems (MDPI) confirms that manure application – including swine manure – consistently increases available phosphorus and stimulates beneficial microbial activity in the soil. However, pig manure is typically high in moisture and odour, and on its own has limited organic bulk. It is most effectively used when composted with straw or other carbon-rich material, which improves handling, reduces odour, and produces a more balanced organic amendment.

Green manure 🔗

Green manure refers to specific crops grown and then incorporated into the soil while still green, before or just after flowering. Leguminous crops such as dhaincha (Sesbania bispinosa), cowpea, clover, and vetch are the most common green manure crops, though non-leguminous species are also used.

The most important contribution of green manuring is biological nitrogen fixation (BNF). According to detailed agronomic literature on green manuring, leguminous species like clover and vetch contain symbiotic Rhizobia bacteria in their root nodules that fix atmospheric nitrogen into a form plants can use, with the nitrogen released into the soil ranging from 45 to 224 kg per hectare depending on species and conditions. A Frontiers in Sustainable Food Systems review notes that the yield gain of cereals following legume green manuring can be equivalent to applying 50-120 kg of nitrogen fertilizer per hectare – a significant saving, especially for smallholder farmers.

Beyond nitrogen, green manure incorporation improves water infiltration, aeration, and humus content, while also suppressing weeds and reducing soil erosion. ATTRA Sustainable Agriculture highlights that high-biomass legume green manures can return 100-200 pounds of nitrogen per acre, potentially eliminating the need for synthetic nitrogen applications entirely in vegetable cropping systems.

Green leaf manures 🔗

Green leaf manures differ from green manure crops in that the plant material is collected from trees, shrubs, or wild vegetation growing elsewhere – not from crops grown in the field itself. Commonly used species include Gliricidia sepium, Calotropis, Leucaena, and neem. The leaves and tender branches are cut and incorporated into the soil before planting.

Green leaf manures are particularly valued in low-input farming systems where growing a full green manure crop may not be feasible. They are rich in nitrogen (especially from fast-growing leguminous trees), decompose rapidly, and boost microbial biomass in the soil. Research documented in Just Agriculture notes that incorporation of green leaf manures like Gliricidia promotes healthy growth in organic paddy plots and improves soil health by positively affecting the physical, chemical, and biological properties of the soil.

Why these organic materials matter in rainfed systems 🔗

In rainfed farming, soils are under constant stress – they must capture and hold every drop of rainfall, while also supplying crops with enough nutrients across an unpredictable season. Organic materials address both challenges simultaneously.

Slow-release nutrition 🔗

Unlike soluble chemical fertilizers that can be washed away in the first heavy rain, organic materials release nutrients gradually as soil microbes break them down. This means nutrients are available when crops actually need them rather than being lost to leaching. The LPELC describes this as a natural slow-release mechanism where manure nitrogen is better timed to crop nitrogen needs than commercial fertilizer nitrogen.

Improved soil structure and water retention 🔗

Organic matter improves soil aggregation, which in turn improves water infiltration and the soil’s ability to hold moisture between rain events. Long-term manure application data shows that organic matter from manure contributes directly to improved water-holding capacity, reduced crop water stress, and lower soil erosion – all critical for rainfed crop stability.

Reduced dependence on chemical fertilizers 🔗

The cost of chemical fertilizers is a persistent burden for smallholder farmers. By substituting or supplementing inorganic inputs with organic materials, farmers can lower input costs while maintaining or even improving yields. eOrganic’s guidance on organic manure management notes that properly managed manure is most effective when used in combination with crop rotation, cover cropping, and green manuring – an integrated approach that reduces dependence on purchased inputs over time.

Microbial activity and long-term soil health 🔗

Organic materials feed the soil food web. A ScienceDirect review on manure and soil biodiversity confirms that manure promotes plant growth, provides nutrition to soil organisms, and adds genetic and functional diversity to soils. This biodiversity is what sustains long-term fertility – organic carbon supports the microbial processes that cycle nutrients, decompose residues, and build stable soil structure season after season.

Practical considerations when using organic materials 🔗

Organic materials are not risk-free. Over-application of manure – particularly phosphorus-rich sources like poultry manure – can lead to nutrient imbalances and phosphorus accumulation in soil. USDA guidance on manure in organic production advises that application rates must always be matched to crop nutrient needs, and that repeated use of the same manure source should be monitored through regular soil testing. Composting raw manures before application reduces pathogen risks, eliminates most weed seeds, and produces a more stable, balanced amendment.

Timing also matters. Applying organic materials too early before planting risks nutrient loss; too late means nutrients may not be available when the crop needs them most. Incorporating green manures before they flower – when their C:N ratio is still low – ensures faster decomposition and quicker nitrogen availability for the following crop.

What do you think? Given that rainfed soils are particularly vulnerable to nutrient depletion and moisture stress, which of these organic materials do you think would have the most impact in a resource-limited farming system – and does the choice change depending on whether a farmer has livestock or not? Would combining multiple organic material types, rather than relying on a single source, produce more consistent results across different soil types?

References

1. https://lpelc.org/environmental-benefits-of-manure-application/
2. https://www.naturallygrown.org/compost-manure-and-the-in-between/
3. https://www.ndsu.edu/agriculture/extension/publications/composting-animal-manures-guide-process-and-management-animal-manure-compost
4. https://www.nature.com/articles/s41598-025-00394-8
5. https://raubikaner.org/wp-content/themes/theme2/PDF/SSAC-311.pdf
6. https://hal.science/hal-04935095v1/file/Ajeet24%20AB-07%20july%202021%20Use%20of%20press%20mud%20for%20sugarcane%20farming%20and%20sustaining%20soil%20health.pdf
7. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0272013
8. https://www.mdpi.com/2571-8789/4/4/64
9. https://en.wikipedia.org/wiki/Green_manure
10. https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2021.767998/full
11. https://attra.ncat.org/publication/overview-of-cover-crops-and-green-manures-2/
12. https://justagriculture.in/wp-content/uploads/2024/12/27.-Importance-of-Green-manuring-and-Green-Leaf-Manuring-in-Soil-Health-Management.pdf
13. https://eorganic.org/node/3132
14. https://www.sciencedirect.com/science/article/pii/S0308521X21002043
15. https://www.ams.usda.gov/sites/default/files/media/Manure%20in%20Organic%20Production%20Systems_FINAL.pdf