Soil Quality in Organic Agriculture



Kathleen DelateIowa State UniversityCynthia Cambardella & Douglas KarlenUSDA National Soil Tilth Laboratory

Full Article : (http://extension.agron.iastate.edu/sustag/pubs/Soil_Quality_Brochure.doc)

Definition of Organic
According to the USDA National Organic Standards Board (NOSB), organic agriculture is defined as "an ecological production management system that promotes and enhances biodiversity, biological cycles, and soil biological activity. It is based on minimal use of off-farm inputs and on management practices that restore, maintain, or enhance ecological harmony. The primary goal of organic agriculture is to optimize the health and productivity of interdependent communities of soil life, plants, animals and people." (NOSB, 1997) The term "organic" is defined by law. In 1990, the U.S. Congress passed the Organic Food Production Act (OFPA). OFPA requires that anyone selling products as "organic" must follow a set of prescribed practices that include avoidance of synthetic chemicals in crop and livestock production, and in the manufacturing of processed products. To sell a product as "organic" the crop must have been raised on land to which no synthetic chemical (any fertilizers, herbicides, insecticides or fungicides) inputs were applied for three years prior to its sale. In addition, no GMO crops are allowed in organic production (e.g. Roundup-Ready® soybeans and Bt-corn®). "Split operations" or conventional and organic fields located on the same farm are allowed by Iowa law, but special care, including a border of 30'  between organic and conventional fields, is needed in mixed operations. Only naturally-occuring materials are allowed in production and processing operations and all treatments must be noted in farm records. Other practices specifically disallowed for organic production in Iowa include the use of "biosolids" or sewage sludge, due to concerns with bacterial and heavy metal contamination.

Soil Health:
The Basis for Organic Farming
The basis for all organic farming systems is the health of the soil. In addition to maintaining adequate fertility, organic farmers strive for biologically-active soil containing microbial populations required for nutrient cycling. Crop rotations, required for all organic operations, provide nutrients, such as nitrogen in the case of legume crops (alfalfa and red clover), and carbonaceous biomass upon which beneficial soil microorganisms depend for survival. Naturally-mined lime products are used to adjust the soil pH to 6-7 (depending on crop requirements). In addition to lime, manure and composted manure are the most common forms of soil amendments for organic operations. Iowa rules require that raw manure be applied three months prior to harvest for agronomic crops and four months for horticultural crops, in order to allow adequate decomposition, and avoid any problems of bacterial contamination of produce. Raw manure cannot be applied to frozen or snow-covered ground. Composting is the preferred method of stabilizing manure. Composting is a controlled process where nitrogen-containing materials (manure, yard/kitchen waste) are mixed with a carbon-containing source (corn stalks/cobs, straw, wood chips) to produce a substance preferably in a Carbon-to-Nitrogen ratio (C:N) of 30 to 1. The compost mixture must reach a temperature of 140° F for at least three days during the composting process. Adequate moisture and temperature are required for proper composting. Additional information on composting practices is listed in the references.
 
There are many soil amendments available for organic farming. The key, however, is that these materials are naturally-based, and that no synthetics are used in the processing or collection of the minerals. In addition to manure-based fertilizers, many organic farmers rely on fish emulsion and seaweed preparations to supply nitrogen and other elements. When phosphorus and potassium are limiting, rock phosphate and naturally-mined potassium chloride are allowed. It is imperative that you check with your certification agency before application of any materials. Should you apply a material found to be contaminated with toxic materials, your certification may be revoked for three years.

Crop Rotations: A Requirement and Wise Practice
In order to be certified, a crop rotation plan must be in place to protect against pest problems and maintain soil health. No more than four out of six years should be in row crops, and the same row crop cannot be grown in consecutive years on the same land. Legumes (alfalfa, red clover, berseem clover, hairy vetch) alone, or in combination with small grains (wheat, oats, barley), must be rotated with row crops (corn, soybeans, amaranth, vegetables) to ensure a healthy system. A typical six-year rotation in Iowa would be corn (with a cover of winter rye)-soybeans-oats (with an underseeding of alfalfa)-alfalfa-corn-soybeans.  Horticultural crops must be rotated with a leguminous cover crop at least once every five years. In research conducted at Iowa State University, after one growing season under organic management, Microbial Biomass Carbon (Mb-C) was 128% greater in the organic system; Maggroaggregate Stability (AggS) 15% greater; Organic Carbon (Org-C) 6% greater; Particulate Organic Matter Carbon (Pom-C) 8% greater; and N mineralization potential (PminN) 7% greater in the organic system. Nitrate N (NO3-N) was 44% greater in the conventional system, as reflected in the excess corn stalk nitrate. 

Menanam Padi Di Halaman Rumah

Menanam Padi di halaman rumah mungkin merupakan hal yang masih baru dan belum terbiasa bagi kondisi masyarakat kita sekarang ini. Namun hal tersebut tidak ada salahnya untuk diamati, pelajari, dan bahkan dipraktekkan. Kondisi lahan persawahan yang semakin menyempit dikarenakan oleh perkembangan wilayah kota semakin luas yang berujung kepada berkurangnya ketersediaan pangan nasional. Dan satu hal lagi yang menjadikan pentingnya menanam padi di halaman rumah yaitu sebagai tonggak untuk berkembangnya kesadaran bertani organik yang dimulai dari rumah sendiri.

Sekarang ini telah dikenal pemahaman baru mengenai tanaman padi yaitu bahwa padi bukan merupakan tanaman air atau dengan kata lain tanaman yang hidup di air dan membutuhkan banyak air untuk pertumbuhannya. Maka pola tanam padi dihalaman rumah dapat diterapkan dengan cara SRI (System of Rice Intensification). Prinsip SRI intinya yaitu penanaman bibit muda dan tunggal, jarak tanam lebar, tidak digenangi dan menggunakan pupuk organik. Dengan Revolusi SRI, kita dapat menanam padi di pekarangan rumah bahkan juga di atap rumah. Tidak melulu harus di sawah kan!

Cara tanam padi dengan Polybag (kantong plastik) merupakan cara yang paling mudah untuk diterapkan di halaman rumah. Pengalaman yang dilakukan petani dan masyarakat menunjukkan hasil yang menggembirakan bahwa padi dapat tumbuh dengan baik dalam polybag. Kabupaten Tasikmalaya disebut-sebut yang memeloporinya dan sudah ditiru di banyak tempat. Dalam satu pot dengan pemupukan optimal dapat menghasilkan sekurangnya 3 – 5 ons gabah per polybag.

Aplikasi tanam padi pada Polybag dapat dilakukan sebagai berikut:

1. Persemaian
Polybag tidak lain adalah tempat persemaian dan tempat tumbuh padi hingga panen. Polibeg ukuran diameter 25-30 cm diisi campuran tanah dengan kompos sekira 70:30 setinggi 25 cm. Tanah sebaiknya diambil dari sawah atau dari tempat lain yang tidak banyak mengandung pasir. Sebelum dimasukkan ke dalam polibeg tanah dengan kompos diaduk merata dalam keadaan kering. Polibeg bisa diganti dengan wadah plastik bekas cat 5kg atau ember. Bagian bawah dilubangi untuk drainase air.

2. Bertanam padi di polibeg bisa menggunakan benih jenis dan varietas apapun. Asalkan sebelum ditanam (ke dalam polibeg) diseleksi dulu untuk mendapatkan benih yang bagus. Caranya dengan merendam benih dalam larutan garam dan abu. Benih yang mengapung dibuang sedangkan benih yang tenggelam yang akan ditanam.

3. Penanaman
Benih yang sudah dipilih tadi ditanam satu polibeg satu benih yang diletakkan di tengah-tengah. Sediakan satu polibeg untuk menanam bibit cadangan sebagai penyulam jika ada bibit yang mati. Setelah satu minggu tinggi tanaman sudah mencapai 7-10 cm.

4. Pengairan
Praktis bertanam padi di polibeg tidak membutuhkan penggenangan. Namun tanah harus dijaga tetap lembab atau basah dan tidak boleh kering. Cara menyiram bisa menggunakan alat penyiram air. Waktu penyiraman dilakukan saat teduh di waktu pagi atau sore (seperti menyiram tanaman hias).

5. Pemupukan
Sejak awal tanah dalam polibeg sebagai tempat pertumbuhan akar sudah mengandung pupuk organik yang berasal dari kompos. Selama pertumbuhan vegetatif tanah harus dipupuk juga untuk mendapatkan hasil yang optimal. Pupuk yang digunakan bisa pupuk organik padat atau cair. Dosis keduanya tidak ada patokan dasarnya. Jika kondisi tanah awal kurang subur penggunaan urea atau pupuk majemuk NPK dianjurkan agar pertumbuhan bagus dan padi menghasilkan bulir yang berisi.

6. Pengendalian hama
Pembasmian hama padi dalam polibeg tidak akan terlalu sulit. Karena memang penanaman padinya skala kecil untuk pekarangan. Dianjurkan menggunakan pestisida nabati yaitu cairan pembasmi hama yang dibuat dari bahan-bahan alami. Sebagai contoh, semut dan walang sangit bisa dibasmi dengan menggunakan campuran bawang putih dan jahe yang dihaluskan kemudian dicampur dengan air.

Dengan luas pekarangan 10 m2 anda sekurangnya sudah mempunyai 100 polibeg padi. Ini artinya anda bisa menghasilkan sumber pangan utama sendiri. Dengan demikian ketahanan pangan sesungguhnya bisa dimulai dari rumah tangga. Anda berminat mencobanya?

The Practice of SRI on Rainfed Marginal Lands

by Dr. J.N. Daniel

The merits of the System of Rice Intensification (SRI) are highlighted extensively in contemporary literature.  Many aspects of SRI, such as the use of organic matter, traditional rice varieties and non-flooding of fields are appealing to small farmers operating under resource-limited conditions.  Enthused by these favourable attributes, BAIF Development Research Foundation in India experimented with SRI in its rural development project areas of Gujarat and Maharashtra states.  This initiative saw tribal farmers growing rice with the SRI method in small plots in parts of their rice fields.  The traditional method of cultivation is to grow rice on puddled soil in terraced plots.  Rice is the staple food of these marginal farmers and the rice produced, usually in the range of 1.0-2.0 tons per ha, was primarily for home consumption.  Cultivation was almost totally dependent on monsoon rains and the use of improved varietes and chemical inputs is not uncommon in recent years.

The performance of rice in the SRI plots was generally in agreement with positive attributes such as profuse tillering and dense rooting, which are highlighted in literature.  SRI appears promising, but certain practical difficulties may constrain its rapid diffusion among farmers in the project areas where it was tried by BAIF.  The aim of this paper is to share these observations with those who are in the forefront of promoting and further evolving this method of rice cultivation.

Seedling age at planting

The traditional practice of tribal communities in the project area is to sterilise the nursery bed by spreading a layer of biomass and burning it.  Although each farmer burns only a small quantity of biomass, the total loss for the entire area taken together is substantial.  In such a situation, planting single seedlings that are 10-12 days old is advantageous because the nursery can be a tray or a small plot in the kitchen garden. 

Although transplanting four-week old seedlings is the traditional practice, heavy rains may force a delay by another week or two at times.  In SRI, a farmer may start the nursery expecting to transplant on a particular day; but a few days of continuous rains around the designated day would render the field unsuitable and the seedlings would have become too old by the time conditions improve.  The rainfall during the months of June and July, when land preparation and crop establishement operations are done, can exceed 1000 mm in the project area.  Unlike in irrigated cultivation, rainfed rice requires greater flexibility in seedling age at planting, which is not there in the SRI method. 

Associated with timeliness of transplanting is the aspect of labour sharing by small communities.  The demand on labour usually peaks at the time of transplanting and again at harvesting.  The practice among the farming communities in the project area is to share the family labour for these two operations.  There is greater flexibility in the present method as the seedlings at transplanting are 25-35 days old.  This age difference of 10 days enables easier sharing of the family labour among neighbouring farmers.  The SRI requirement of 10-12 day old seedlings means less flexibility with regard to age as the range is only two days.  This situation is further aggravated by the need to transplant single seedlings, which is laborious and time consuming.  

Water management

SRI requires maintaining the field under saturated conditions immediately after transplanting and then having a wetting and drying cycle.  Strictly following such a water management regime was found to be difficult under the rainfed conditions of the project area.  In some farms, heavy rains immediately after transplanting uprooted or submerged the seedlings.  This resulted in slow early establishment as well as gaps due to loss of seedlings.  Ensuring regular wetting and drying cycles was also not possible under rainfed conditions.  The levelling of the fields was not uniform in spite of the best efforts of the farmers.  This resulted in seedlings in elevated spots wilting during the drying cycle and sometimes not recovering at all.  Not that these cannot be overcome; mere sprinkling of water can revive the plants.

Organic manure

In general, the fertility of land of project participants is low.  Introduction of practices such as soil conservation and organic manure application has resulted in some improvement.  However, the soil fertility in most of the farms is below average.  Organic matter available for use as manure is limited.  Even households that have two head of cattle cannot produce more than 5.0 tons of manure whereas SRI would require the application of at least 10 t per ha.  Besides the nutrient supply aspect, the organic matter content of the soil for water retention is another important consideration.  Probably due to the low organic matter content, soil tended to dry up rapidly after it was wetted.  Under rainfed conditions, if the next rains are not received in time, there is a likelihood of the crop experiencing a drought stress.  In such situations, the traditional practice of flooding gives a few more days of cushoning in the form of standing water in the field. 

Concluding Remarks

Transition from a traditional method to another is not always easy.  Some changes required for SRI, such as the planting of single seedlings and the resultant increase in labour, can be overcome with practice.  There are others where the difficulties pertain to resource conditions like water availability and soil fertility.  Addressing these issues probably require trying out modifications to suit the local conditions.

Source : (http://www.baif.org.in/doc/Sustainable_Agriculture/LEISA-SRI.doc)

Kesalahan Persepsi Pertanian Organik

Masyarakat awam menganggap produk organik adalah produk yang bagus tidak hanya dari segi kandungan nutrisi namun juga penampilan produknya. Kenyataannya produk organik itu tidaklah selalu bagus, sebagai contoh daun berlobang dan berukuran kecil, karena tidak menggunakan pestisida dan zat perangsang tumbuh atau pupuk an organik lainnya. Pada tahun awal pertaniannya belum menghasilkan produk yang sesuai harapan.

Sebagian petani kita terbiasa menggunakan pupuk an organik yang akan memberikan respon cepat pada tanaman. Seperti misalnya pemupukan Urea akan menghasilkan tanaman yang pertumbuhannya cepat, sementara dengan pemupukan organik pengaruh perubahan pertumbuhan tanaman tergolong lambat. Baru pada musim ketiga dan seterusnya, efek pupuk organik tersebut menunjukkan hasil yang nyata perbedaannya dengan pertanian non organik. Sehingga dapat disimpulkan pertanian organik di tahun-tahun awal akan mengalami banyak kendala dan membutuhkan modal yang cukup untuk bertahan.

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