The Vital Link: Organic Matter and Plant Productivity

Why should we add well decayed organic matter and basal fertilizer to the soil before transplanting seedlings or grafted plants of perennial crop species?

Because organic matter is closely linked to plant productivity. In case the soil does not contain the nutrients that the crops needed especially seedlings and grafted plants of perennial crop species, the organic matter and fertilizer that were mixed with the soil will immediately fill the need of starting-to-grow crops. Consequently, landscapes with variable organic matter usually show variations in productivity.

Plants growing in well-aerated soils are less stressed by drought or excess water. In soils with less compaction, plant roots can penetrate and flourish more readily. High organic matter increases productivity and, in turn, high productivity increases organic matter.

Also, crop yields in systems with high soil organic matter content are less variable than those in soil that are low in organic matter. This is because of the stabilizing effects of favourable conditions of soil properties and microclimate.

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Any form of human intervention influences the activity of soil organisms (Curry and Good, 1992) and thus the equilibrium of the system. Management practices that alter the living and nutrient conditions of soil organisms, such as repetitive tillage or burning of vegetation, result in a degradation of their microenvironments.

In turn, this results in a reduction of soil biota, both in biomass and diversity. Where there are no longer organisms to decompose soil organic matter and bind soil particles, the soil structure is damaged easily by rain, wind and sun.

This can lead to rainwater runoff and soil erosion (Plate 3), removing the potential food for organisms, i.e. the organic matter of the topsoil. Therefore, soil biota are the most important property of the soil, and “when devoid of its biota, the uppermost layer of earth ceases to be soil” (Lal, 1991).

4.) What are the different adaptive tillage operations? Characterize each.

Types of Tillage Operations: Tillage includes use of different kinds of implements at different times are classified on the basis of their timing into-3types: 1. Preparatory tillage: Tillage operations that are carried out from the time of harvest of a crop to the sowing of the next crop are known as preparatory cultivation/ Tillage. OR Operations carried out in any cultivated land to prepare seedbed for sowing crops are preparatory tillage. These are time consuming & costly but are to be performed at right stage of soil moisture & with right implements, otherwise it will not helps in good growth of crop. These includes in sequence, plouging, clod crushing, leveling, discing , harrowing, manure mixing & compacting the soil and implements to be used are ploughs, clod crushers, disc ploughs or harrow , bladed harrow etc. It includes primary & secondary tillage:

a) Primary tillage: It mainly includes the ploughing operation which is opening of the compacted soil with the help of different ploughs. Ploughing is done to:

1. Open the hard soil,
2. Separate the top soil from lower layers,
3. Invert the soil whenever necessary and
4. Uproot the weeds & stubbles.

The cutting & inverting of the soil that is done after the harvest of the crop or untitled fallow or to bring virgin or new land under cultivation is called primary tillage. It may be done once or twice a tear in normal or settled agriculture or once in four to five years in dry land agriculture. b) Secondary tillage: Lighter or finer operation performed on the soil after primary tillage are known as secondary tillage which includes the operations performed after ploughing, leveling, discing, harrowing etc.

Seedbed preparation: when the soil is brought to a condition suitable for germination of seeds & growth of crops, called as SEEDBED.

After preparatory tillage the land is to be laid out properly for irrigating crops if irrigation is available for sowing or planting seeding which are known as seedbed preparation: It includes harrowing, leveling, compacting the soil, preparing irrigation layouts such as basins, borders, rides & furrows etc. and carried out by using hand tools or implements like harrow, rollers plank, rider etc. After field preparation, sowing is done with seed drills. Seeds are covered & planking is done so as to level & impart necessary compaction.

Inter tillage/ Inter cultivation/ Interculture/ after care operation: The tillage operations that are carried out in the standing crop are called inter tillage operations. The tillage operation done in the field after sowing or planting and prior to the harvesting of crop plants known as inter cultivation. It includes gap filling , thinning , weeding , mulching, top dressing of fertilizers, hoeing, earthling up etc. unless these are carried out at right time, with suitable implements mainly hoes & hand tools the crop will not attain a vigorous growth. These operations are carried out in between the crop rows.

Primary Tillage

Deep ploughing, from its name itself, is a tillage operation in which the soil is plough deeply signifying a high degree of soil disturbance and includes inversion. It turns out large sized clods, which are baked by the hot sun when it is done in summer. These clods crumble due to alternate heating and cooling and due to occasional summer showers. This process of gradual disintegration of clods improves soil structure.

A deep tillage of 25-30 cm depth is necessary for deep rooted crop like pigeon pea while moderate deep tillage of 15-20 cm is required for maize. Deep tillage also improves soil moisture content. However the advantage of deep tillage in dry farming condition depends on rainfall pattern and crop. It is advisable to go for deep ploughing only for long duration, deep rooted crops. Depth of ploughing should be related to the amount of rainfall that it can wet. -Sub-soiling is breaking the hard pan without inversion and with less disturbance of top soil. These may be silt pans, iron or aluminium pans, clay pans or -man-made pans. Man-made pans are tillage pans induced by repeated tillage at the same depth. Root growth of crops is confined to top few centimetres of soil where deep penetration of roots is inhibited by hard pans.

For example, cotton roots grow to a depth of 2 m in deep alluvial soil without any pans. When hard pans are present, they grow only up to hard pan, say 15-20 cm. Similarly, vertical root growth of sugarcane is restricted due to hard pans and it is not compensated by horizontal spread. Subsoiling is breaking the hard pan without inversion and with less disturbance of top soil. A narrow cut is made in the top soil while share of the subsoiler shatters hard pans. Chisel ploughs are also used to break hard pans present even at 60-70 cm. The effect of subsoiling does not last long. To avoid closing of subsoil furrow, vertical mulching is adopted.

Year-round tillage is a collective term for tillage operations carried out throughout the year. Tillage operations carried out throughout the year are known as year-round tillage. In dry farming regions, field preparation is initiated with the help of summer showers. Repeated tillage operations are carried out until sowing of the crop. Even after harvest of the crop, the field is repeatedly ploughed or harrowed to avoid weed growth in the off season.

Secondary tillage: lighter or finer operations performed on the soil after primary tillage. Lighter or finer operations performed on the soil after primary tillage are known as secondary tillage. After ploughing, the fields are left with large clods with some weeds and stubbles partially uprooted. Harrowing is done to a shallow depth to crush the clods and to uproot the remaining weeds and stubbles. Disc harrows, cultivators, blade harrows etc., are used for this purpose.

Planking is done to crush the hard clods to smoothen the soil surface and to compact the soil lightly. Thus the field is made ready for sowing after ploughing by harrowing and planking. Generally sowing operations are also included in secondary tillage.

-Conventional tillage–signifying a high degree of soil disturbance -Reduced tillage –in which one or more of the conventional tillage operations are eliminated -Conservation tillage -in which there is minimal soil disturbance and crop residues are, if at all possible, left on the surface to protect and benefit the soil. Normally refers to tillage systems that do not invert the soil, which retain crop residues on the surface, and which optimize soil and water conservation. It is a generic term that covers any tillage system that reduces loss of soil and water compared with conventional tillage. Some have defined it more tightly to include treatment of residues specifying that at least 30 percent of the soil surface should be covered with residues after sowing so as to reduce erosion by water. It is likely to include zero, minimum and reduced tillage systems within the definition.

Differentiate between minimum and zero tillage.

>Zero tillage a way of growing crops or pasture from year to year without disturbing thesoil through tillage. No-till is an agricultural technique which increases the amount of water that infiltrates into the soil and increases organic matter retention and cycling of nutrients in the soil. In many agricultural regions it can reduce or eliminate soil erosion. It increases the amount and variety of life in and on the soil, including disease-causing organisms and disease suppression organisms. The most powerful benefit of no-tillage is improvement in soil biological fertility, making soils more resilient. Farm operations are made much more efficient, particularly improved time of sowing and better trafficability of farm operations. refers to direct planting into the residues and stubble of a previous crop, or the mulch of a cover crop or fallow, without any previous tillage or soil disturbance, except that which is necessary to place the seed in the soil. Or in other words, there’s no plowing or harrowing done while

>Minimum Tillage concept come into existence reduing time, labour and machine operations as well as conserving moisture and reducing erosion. The modern technology of herbicides & insecticides made it possible to achieve some tillage requirements without using implements. Any tillage practice in dry lands which does not return more than its cost by increasing yield and improving soil conditions should be eliminated. Soil need to be worked only enough to assure optimum crop production and weed control. combines several operations into one pass e.g. plow-plant method, rotavation.

A. Written Report of the Field Practices Conducted During the Different Growth Stages of Lowland Rice

Rice with all its importance is growing through cultivation. This practices that makes it more fruitful is partly in man's hands. As we finally knew more about rice- its different growth stages and its cultivation practices, I really appreciate it even more. The world’s population, affirmed the need to heighten the awareness of the role of rice in alleviating poverty and malnutrition and reaffirmed the need to focus world attention on the role rice can play in providing food security and eradicating poverty, with these, growth of rice is essential.

The growth of rice plant begins with fertilization and embryonic development. Like most of all the embryonic developments, it germinates with the application of moisture and heat and soon develops into seedlings. From seeds to seedlings to grown plant and reach maturity, there are distinct phases with distinct stages and these stages have different field practices to ensure maximum yield

Rice is one of the most important food crops in the world, and staple for more than half of the global population. Looming water crisis, water-intensive nature of rice cultivation and escalating labour costs drive the search for alternative management methods to increase water productivity in rice cultivation. Direct seeded rice (DSR) has received much attention because of its low-input demand. It involves sowing pre-germinated seed into a puddled soil surface (wet seeding), standing water (water seeding) or dry seeding into a prepared seedbed (dry seeding). In Europe, Australia and the United States, DSR is highly mechanised. The development of early-maturing varieties and improved nutrient management techniques along with increased availability of chemical weed control methods has encouraged many farmers in the Philippines, Malaysia, Thailand and India to switch from transplanted to DSR culture.

This shift should substantially reduce crop water requirements, soil organic-matter turnover, nutrient relations, carbon sequestering, weed biota and greenhouse-gas emissions. Still, weed infestation can cause large yield losses in DSR. In addition, recent incidences of blast disease, crop lodging, impaired kernel quality and stagnant yields across the years are major challenges in this regard. In this review, we discuss the experiences, potential advantages and problems associated with DSR, and suggest likely future patterns of changes in rice cultivation.